diff options
Diffstat (limited to 'runtime/relayfs')
| -rw-r--r-- | runtime/relayfs/ChangeLog | 21 | ||||
| -rw-r--r-- | runtime/relayfs/Makefile | 17 | ||||
| -rw-r--r-- | runtime/relayfs/buffers.c | 195 | ||||
| -rw-r--r-- | runtime/relayfs/buffers.h | 12 | ||||
| -rw-r--r-- | runtime/relayfs/inode.c | 437 | ||||
| -rw-r--r-- | runtime/relayfs/linux/relayfs_fs.h | 267 | ||||
| -rw-r--r-- | runtime/relayfs/relay.c | 545 | ||||
| -rw-r--r-- | runtime/relayfs/relay.h | 12 | ||||
| -rw-r--r-- | runtime/relayfs/relayfs.txt | 214 |
9 files changed, 0 insertions, 1720 deletions
diff --git a/runtime/relayfs/ChangeLog b/runtime/relayfs/ChangeLog deleted file mode 100644 index 09f237a2..00000000 --- a/runtime/relayfs/ChangeLog +++ /dev/null @@ -1,21 +0,0 @@ -2005-10-19 Tom Zanussi <zanussi@us.ibm.com> - - * inode.c (relayfs_remove): Applied patch - [PATCH 2.6.13-rc6-mm2] relayfs: relayfs_remove fix - -2005-10-14 Tom Zanussi <zanussi@us.ibm.com> - - * buffers.c (relay_alloc_buf): Applied patch - [PATCH 2.6.14-rc4] relayfs: fix bogus param value in call to vmap - -2005-05-17 Martin Hunt <hunt@redhat.com> - - * relay.c (relay_switch_subbuf): Applied patch - [PATCH 2.6.12-rc1-mm2] relayfs: properly handle oversized events - -2005-04-11 Martin Hunt <hunt@redhat.com> - - * inode.c: Latest kernels have modified backing_dev_info. Detect - newer version and set appropriately. - - diff --git a/runtime/relayfs/Makefile b/runtime/relayfs/Makefile deleted file mode 100644 index b9f2facf..00000000 --- a/runtime/relayfs/Makefile +++ /dev/null @@ -1,17 +0,0 @@ -# -# relayfs Makefile -# - -PWD := $(shell pwd) -KDIR := /lib/modules/$(shell uname -r)/build - -relayfs-y := relay.o inode.o buffers.o - -obj-m += relayfs.o - -default: - $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules - -clean: - /bin/rm -rf *.o *.ko *~ *.mod.c .*.cmd .tmp_versions - diff --git a/runtime/relayfs/buffers.c b/runtime/relayfs/buffers.c deleted file mode 100644 index 0fa7ceae..00000000 --- a/runtime/relayfs/buffers.c +++ /dev/null @@ -1,195 +0,0 @@ -/* - * RelayFS buffer management code. - * - * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp - * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) - * - * This file is released under the GPL. - */ - -#include <linux/module.h> -#include <linux/vmalloc.h> -#include <linux/mm.h> -#include "linux/relayfs_fs.h" -#include "relay.h" -#include "buffers.h" - -/* - * close() vm_op implementation for relayfs file mapping. - */ -static void relay_file_mmap_close(struct vm_area_struct *vma) -{ - struct rchan_buf *buf = vma->vm_private_data; - buf->chan->cb->buf_unmapped(buf, vma->vm_file); -} - -/* - * nopage() vm_op implementation for relayfs file mapping. - */ -static struct page *relay_buf_nopage(struct vm_area_struct *vma, - unsigned long address, - int *type) -{ - struct page *page; - struct rchan_buf *buf = vma->vm_private_data; - unsigned long offset = address - vma->vm_start; - - if (address > vma->vm_end) - return NOPAGE_SIGBUS; /* Disallow mremap */ - if (!buf) - return NOPAGE_OOM; - - page = vmalloc_to_page(buf->start + offset); - if (!page) - return NOPAGE_OOM; - get_page(page); - - if (type) - *type = VM_FAULT_MINOR; - - return page; -} - -/* - * vm_ops for relay file mappings. - */ -static struct vm_operations_struct relay_file_mmap_ops = { - .nopage = relay_buf_nopage, - .close = relay_file_mmap_close, -}; - -/** - * relay_mmap_buf: - mmap channel buffer to process address space - * @buf: relay channel buffer - * @vma: vm_area_struct describing memory to be mapped - * - * Returns 0 if ok, negative on error - * - * Caller should already have grabbed mmap_sem. - */ -int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma) -{ - unsigned long length = vma->vm_end - vma->vm_start; - struct file *filp = vma->vm_file; - - if (!buf) - return -EBADF; - - if (length != (unsigned long)buf->chan->alloc_size) - return -EINVAL; - - vma->vm_ops = &relay_file_mmap_ops; - vma->vm_private_data = buf; - buf->chan->cb->buf_mapped(buf, filp); - - return 0; -} - -/** - * relay_alloc_buf - allocate a channel buffer - * @buf: the buffer struct - * @size: total size of the buffer - * - * Returns a pointer to the resulting buffer, NULL if unsuccessful - */ -static void *relay_alloc_buf(struct rchan_buf *buf, unsigned long size) -{ - void *mem; - int i, j, n_pages; - - size = PAGE_ALIGN(size); - n_pages = size >> PAGE_SHIFT; - - buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL); - if (!buf->page_array) - return NULL; - - for (i = 0; i < n_pages; i++) { - buf->page_array[i] = alloc_page(GFP_KERNEL); - if (unlikely(!buf->page_array[i])) - goto depopulate; - } - mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL); - if (!mem) - goto depopulate; - - memset(mem, 0, size); - buf->page_count = n_pages; - return mem; - -depopulate: - for (j = 0; j < i; j++) - __free_page(buf->page_array[j]); - kfree(buf->page_array); - return NULL; -} - -/** - * relay_create_buf - allocate and initialize a channel buffer - * @alloc_size: size of the buffer to allocate - * @n_subbufs: number of sub-buffers in the channel - * - * Returns channel buffer if successful, NULL otherwise - */ -struct rchan_buf *relay_create_buf(struct rchan *chan) -{ - struct rchan_buf *buf = kcalloc(1, sizeof(struct rchan_buf), GFP_KERNEL); - if (!buf) - return NULL; - - buf->padding = kmalloc(chan->n_subbufs * sizeof(unsigned *), GFP_KERNEL); - if (!buf->padding) - goto free_buf; - - buf->commit = kmalloc(chan->n_subbufs * sizeof(unsigned *), GFP_KERNEL); - if (!buf->commit) - goto free_buf; - - buf->start = relay_alloc_buf(buf, chan->alloc_size); - if (!buf->start) - goto free_buf; - - buf->chan = chan; - kref_get(&buf->chan->kref); - return buf; - -free_buf: - kfree(buf->commit); - kfree(buf->padding); - kfree(buf); - return NULL; -} - -/** - * relay_destroy_buf - destroy an rchan_buf struct and associated buffer - * @buf: the buffer struct - */ -void relay_destroy_buf(struct rchan_buf *buf) -{ - struct rchan *chan = buf->chan; - int i; - - if (likely(buf->start)) { - vunmap(buf->start); - for (i = 0; i < buf->page_count; i++) - __free_page(buf->page_array[i]); - kfree(buf->page_array); - } - kfree(buf->padding); - kfree(buf->commit); - kfree(buf); - kref_put(&chan->kref, relay_destroy_channel); -} - -/** - * relay_remove_buf - remove a channel buffer - * - * Removes the file from the relayfs fileystem, which also frees the - * rchan_buf_struct and the channel buffer. Should only be called from - * kref_put(). - */ -void relay_remove_buf(struct kref *kref) -{ - struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref); - relayfs_remove(buf->dentry); -} diff --git a/runtime/relayfs/buffers.h b/runtime/relayfs/buffers.h deleted file mode 100644 index 37a12493..00000000 --- a/runtime/relayfs/buffers.h +++ /dev/null @@ -1,12 +0,0 @@ -#ifndef _BUFFERS_H -#define _BUFFERS_H - -/* This inspired by rtai/shmem */ -#define FIX_SIZE(x) (((x) - 1) & PAGE_MASK) + PAGE_SIZE - -extern int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma); -extern struct rchan_buf *relay_create_buf(struct rchan *chan); -extern void relay_destroy_buf(struct rchan_buf *buf); -extern void relay_remove_buf(struct kref *kref); - -#endif/* _BUFFERS_H */ diff --git a/runtime/relayfs/inode.c b/runtime/relayfs/inode.c deleted file mode 100644 index 26faf9fb..00000000 --- a/runtime/relayfs/inode.c +++ /dev/null @@ -1,437 +0,0 @@ -/* - * VFS-related code for RelayFS, a high-speed data relay filesystem. - * - * Copyright (C) 2003-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp - * Copyright (C) 2003-2005 - Karim Yaghmour <karim@opersys.com> - * - * Based on ramfs, Copyright (C) 2002 - Linus Torvalds - * - * This file is released under the GPL. - */ - -#include <linux/module.h> -#include <linux/fs.h> -#include <linux/mount.h> -#include <linux/pagemap.h> -#include <linux/init.h> -#include <linux/string.h> -#include <linux/backing-dev.h> -#include <linux/namei.h> -#include <linux/poll.h> -#include "linux/relayfs_fs.h" -#include "relay.h" -#include "buffers.h" - -#define RELAYFS_MAGIC 0xF0B4A981 - -static struct vfsmount * relayfs_mount; -static int relayfs_mount_count; -static kmem_cache_t * relayfs_inode_cachep; - -static struct backing_dev_info relayfs_backing_dev_info = { - .ra_pages = 0, /* No readahead */ -#ifdef BDI_CAP_NO_ACCT_DIRTY - .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, -#else - .memory_backed = 1, /* Does not contribute to dirty memory */ -#endif -}; - -static struct inode *relayfs_get_inode(struct super_block *sb, int mode, - struct rchan *chan) -{ - struct rchan_buf *buf = NULL; - struct inode *inode; - - if (S_ISREG(mode)) { - BUG_ON(!chan); - buf = relay_create_buf(chan); - if (!buf) - return NULL; - } - - inode = new_inode(sb); - if (!inode) { - relay_destroy_buf(buf); - return NULL; - } - - inode->i_mode = mode; - inode->i_uid = 0; - inode->i_gid = 0; - inode->i_blksize = PAGE_CACHE_SIZE; - inode->i_blocks = 0; - inode->i_mapping->backing_dev_info = &relayfs_backing_dev_info; - inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; - switch (mode & S_IFMT) { - case S_IFREG: - inode->i_fop = &relayfs_file_operations; - RELAYFS_I(inode)->buf = buf; - break; - case S_IFDIR: - inode->i_op = &simple_dir_inode_operations; - inode->i_fop = &simple_dir_operations; - - /* directory inodes start off with i_nlink == 2 (for "." entry) */ - inode->i_nlink++; - break; - default: - break; - } - - return inode; -} - -/** - * relayfs_create_entry - create a relayfs directory or file - * @name: the name of the file to create - * @parent: parent directory - * @mode: mode - * @chan: relay channel associated with the file - * - * Returns the new dentry, NULL on failure - * - * Creates a file or directory with the specifed permissions. - */ -static struct dentry *relayfs_create_entry(const char *name, - struct dentry *parent, - int mode, - struct rchan *chan) -{ - struct qstr qname; - struct dentry *d; - struct inode *inode; - int error = 0; - - BUG_ON(!name || !(S_ISREG(mode) || S_ISDIR(mode))); - - error = simple_pin_fs("relayfs", &relayfs_mount, &relayfs_mount_count); - if (error) { - printk(KERN_ERR "Couldn't mount relayfs: errcode %d\n", error); - return NULL; - } - - qname.name = name; - qname.len = strlen(name); - qname.hash = full_name_hash(name, qname.len); - - if (!parent && relayfs_mount && relayfs_mount->mnt_sb) - parent = relayfs_mount->mnt_sb->s_root; - - if (!parent) { - simple_release_fs(&relayfs_mount, &relayfs_mount_count); - return NULL; - } - - parent = dget(parent); - down(&parent->d_inode->i_sem); - d = lookup_hash(&qname, parent); - if (IS_ERR(d)) { - d = NULL; - goto release_mount; - } - - if (d->d_inode) { - d = NULL; - goto release_mount; - } - - inode = relayfs_get_inode(parent->d_inode->i_sb, mode, chan); - if (!inode) { - d = NULL; - goto release_mount; - } - - d_instantiate(d, inode); - dget(d); /* Extra count - pin the dentry in core */ - - if (S_ISDIR(mode)) - parent->d_inode->i_nlink++; - - goto exit; - -release_mount: - simple_release_fs(&relayfs_mount, &relayfs_mount_count); - -exit: - up(&parent->d_inode->i_sem); - dput(parent); - return d; -} - -/** - * relayfs_create_file - create a file in the relay filesystem - * @name: the name of the file to create - * @parent: parent directory - * @mode: mode, if not specied the default perms are used - * @chan: channel associated with the file - * - * Returns file dentry if successful, NULL otherwise. - * - * The file will be created user r on behalf of current user. - */ -struct dentry *relayfs_create_file(const char *name, struct dentry *parent, - int mode, struct rchan *chan) -{ - if (!mode) - mode = S_IRUSR; - mode = (mode & S_IALLUGO) | S_IFREG; - - return relayfs_create_entry(name, parent, mode, chan); -} - -/** - * relayfs_create_dir - create a directory in the relay filesystem - * @name: the name of the directory to create - * @parent: parent directory, NULL if parent should be fs root - * - * Returns directory dentry if successful, NULL otherwise. - * - * The directory will be created world rwx on behalf of current user. - */ -struct dentry *relayfs_create_dir(const char *name, struct dentry *parent) -{ - int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; - return relayfs_create_entry(name, parent, mode, NULL); -} - -/** - * relayfs_remove - remove a file or directory in the relay filesystem - * @dentry: file or directory dentry - * - * Returns 0 if successful, negative otherwise. - */ -int relayfs_remove(struct dentry *dentry) -{ - struct dentry *parent; - int error = 0; - - if (!dentry) - return -EINVAL; - parent = dentry->d_parent; - if (!parent) - return -EINVAL; - - parent = dget(parent); - down(&parent->d_inode->i_sem); - if (dentry->d_inode) { - if (S_ISDIR(dentry->d_inode->i_mode)) - error = simple_rmdir(parent->d_inode, dentry); - else - error = simple_unlink(parent->d_inode, dentry); - if (!error) - d_delete(dentry); - } - if (!error) - dput(dentry); - up(&parent->d_inode->i_sem); - dput(parent); - - if (!error) - simple_release_fs(&relayfs_mount, &relayfs_mount_count); - - return error; -} - -/** - * relayfs_remove_dir - remove a directory in the relay filesystem - * @dentry: directory dentry - * - * Returns 0 if successful, negative otherwise. - */ -int relayfs_remove_dir(struct dentry *dentry) -{ - return relayfs_remove(dentry); -} - -/** - * relayfs_open - open file op for relayfs files - * @inode: the inode - * @filp: the file - * - * Increments the channel buffer refcount. - */ -int relayfs_open(struct inode *inode, struct file *filp) -{ - struct rchan_buf *buf = RELAYFS_I(inode)->buf; - kref_get(&buf->kref); - - return 0; -} - -/** - * relayfs_mmap - mmap file op for relayfs files - * @filp: the file - * @vma: the vma describing what to map - * - * Calls upon relay_mmap_buf to map the file into user space. - */ -int relayfs_mmap(struct file *filp, struct vm_area_struct *vma) -{ - struct inode *inode = filp->f_dentry->d_inode; - return relay_mmap_buf(RELAYFS_I(inode)->buf, vma); -} - -/** - * relayfs_poll - poll file op for relayfs files - * @filp: the file - * @wait: poll table - * - * Poll implemention. - */ -unsigned int relayfs_poll(struct file *filp, poll_table *wait) -{ - unsigned int mask = 0; - struct inode *inode = filp->f_dentry->d_inode; - struct rchan_buf *buf = RELAYFS_I(inode)->buf; - - if (buf->finalized) - return POLLERR; - - if (filp->f_mode & FMODE_READ) { - poll_wait(filp, &buf->read_wait, wait); - if (!relay_buf_empty(buf)) - mask |= POLLIN | POLLRDNORM; - } - - return mask; -} - -/** - * relayfs_release - release file op for relayfs files - * @inode: the inode - * @filp: the file - * - * Decrements the channel refcount, as the filesystem is - * no longer using it. - */ -int relayfs_release(struct inode *inode, struct file *filp) -{ - struct rchan_buf *buf = RELAYFS_I(inode)->buf; - kref_put(&buf->kref, relay_remove_buf); - - return 0; -} - -/** - * relayfs alloc_inode() implementation - */ -static struct inode *relayfs_alloc_inode(struct super_block *sb) -{ - struct relayfs_inode_info *p = kmem_cache_alloc(relayfs_inode_cachep, SLAB_KERNEL); - if (!p) - return NULL; - p->buf = NULL; - - return &p->vfs_inode; -} - -/** - * relayfs destroy_inode() implementation - */ -static void relayfs_destroy_inode(struct inode *inode) -{ - if (RELAYFS_I(inode)->buf) - relay_destroy_buf(RELAYFS_I(inode)->buf); - - kmem_cache_free(relayfs_inode_cachep, RELAYFS_I(inode)); -} - -static void init_once(void *p, kmem_cache_t *cachep, unsigned long flags) -{ - struct relayfs_inode_info *i = p; - if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) - inode_init_once(&i->vfs_inode); -} - -struct file_operations relayfs_file_operations = { - .open = relayfs_open, - .poll = relayfs_poll, - .mmap = relayfs_mmap, - .release = relayfs_release, -}; - -static struct super_operations relayfs_ops = { - .statfs = simple_statfs, - .drop_inode = generic_delete_inode, - .alloc_inode = relayfs_alloc_inode, - .destroy_inode = relayfs_destroy_inode, -}; - -static int relayfs_fill_super(struct super_block * sb, void * data, int silent) -{ - struct inode *inode; - struct dentry *root; - int mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; - - sb->s_blocksize = PAGE_CACHE_SIZE; - sb->s_blocksize_bits = PAGE_CACHE_SHIFT; - sb->s_magic = RELAYFS_MAGIC; - sb->s_op = &relayfs_ops; - inode = relayfs_get_inode(sb, mode, NULL); - - if (!inode) - return -ENOMEM; - - root = d_alloc_root(inode); - if (!root) { - iput(inode); - return -ENOMEM; - } - sb->s_root = root; - - return 0; -} - -static struct super_block * relayfs_get_sb(struct file_system_type *fs_type, - int flags, const char *dev_name, - void *data) -{ - return get_sb_single(fs_type, flags, data, relayfs_fill_super); -} - -static struct file_system_type relayfs_fs_type = { - .owner = THIS_MODULE, - .name = "relayfs", - .get_sb = relayfs_get_sb, - .kill_sb = kill_litter_super, -}; - -static int __init init_relayfs_fs(void) -{ - int err; - - relayfs_inode_cachep = kmem_cache_create("relayfs_inode_cache", - sizeof(struct relayfs_inode_info), 0, - 0, init_once, NULL); - if (!relayfs_inode_cachep) - return -ENOMEM; - - err = register_filesystem(&relayfs_fs_type); - if (err) - kmem_cache_destroy(relayfs_inode_cachep); - - return err; -} - -static void __exit exit_relayfs_fs(void) -{ - unregister_filesystem(&relayfs_fs_type); - kmem_cache_destroy(relayfs_inode_cachep); -} - -module_init(init_relayfs_fs) -module_exit(exit_relayfs_fs) - -EXPORT_SYMBOL_GPL(relayfs_open); -EXPORT_SYMBOL_GPL(relayfs_poll); -EXPORT_SYMBOL_GPL(relayfs_mmap); -EXPORT_SYMBOL_GPL(relayfs_release); -EXPORT_SYMBOL_GPL(relayfs_file_operations); -EXPORT_SYMBOL_GPL(relayfs_create_dir); -EXPORT_SYMBOL_GPL(relayfs_remove_dir); - -MODULE_AUTHOR("Tom Zanussi <zanussi@us.ibm.com> and Karim Yaghmour <karim@opersys.com>"); -MODULE_DESCRIPTION("Relay Filesystem"); -MODULE_LICENSE("GPL"); - diff --git a/runtime/relayfs/linux/relayfs_fs.h b/runtime/relayfs/linux/relayfs_fs.h deleted file mode 100644 index 2d270a3f..00000000 --- a/runtime/relayfs/linux/relayfs_fs.h +++ /dev/null @@ -1,267 +0,0 @@ -/* - * linux/include/linux/relayfs_fs.h - * - * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp - * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com) - * - * RelayFS definitions and declarations - */ - -#ifndef _LINUX_RELAYFS_FS_H -#define _LINUX_RELAYFS_FS_H - -#include <linux/config.h> -#include <linux/types.h> -#include <linux/sched.h> -#include <linux/wait.h> -#include <linux/list.h> -#include <linux/fs.h> -#include <linux/poll.h> -#include <linux/kref.h> - -/* - * Tracks changes to rchan_buf struct - */ -#define RELAYFS_CHANNEL_VERSION 3 - -/* - * Per-cpu relay channel buffer - */ -struct rchan_buf -{ - void *start; /* start of channel buffer */ - void *data; /* start of current sub-buffer */ - unsigned offset; /* current offset into sub-buffer */ - atomic_t subbufs_produced; /* count of sub-buffers produced */ - atomic_t subbufs_consumed; /* count of sub-buffers consumed */ - atomic_t unfull; /* state has gone from full to not */ - struct rchan *chan; /* associated channel */ - wait_queue_head_t read_wait; /* reader wait queue */ - struct work_struct wake_readers; /* reader wake-up work struct */ - struct dentry *dentry; /* channel file dentry */ - struct kref kref; /* channel buffer refcount */ - struct page **page_array; /* array of current buffer pages */ - int page_count; /* number of current buffer pages */ - unsigned *padding; /* padding counts per sub-buffer */ - unsigned *commit; /* commit counts per sub-buffer */ - int finalized; /* buffer has been finalized */ -} ____cacheline_aligned; - -/* - * Relay channel data structure - */ -struct rchan -{ - u32 version; /* the version of this struct */ - unsigned subbuf_size; /* sub-buffer size */ - unsigned n_subbufs; /* number of sub-buffers per buffer */ - unsigned alloc_size; /* total buffer size allocated */ - int overwrite; /* overwrite buffer when full? */ - struct rchan_callbacks *cb; /* client callbacks */ - struct kref kref; /* channel refcount */ - void *private_data; /* for user-defined data */ - struct rchan_buf *buf[NR_CPUS]; /* per-cpu channel buffers */ -}; - -/* - * Relayfs inode - */ -struct relayfs_inode_info -{ - struct inode vfs_inode; - struct rchan_buf *buf; -}; - -static inline struct relayfs_inode_info *RELAYFS_I(struct inode *inode) -{ - return container_of(inode, struct relayfs_inode_info, vfs_inode); -} - -/* - * Relay channel client callbacks - */ -struct rchan_callbacks -{ - /* - * subbuf_start - called on buffer-switch to a new sub-buffer - * @buf: the channel buffer containing the new sub-buffer - * @subbuf: the start of the new sub-buffer - * @prev_subbuf_idx: the previous sub-buffer's index - * @prev_subbuf: the start of the previous sub-buffer - * - * The client should return the number of bytes it reserves at - * the beginning of the sub-buffer, 0 if none. - * - * NOTE: subbuf_start will also be invoked when the buffer is - * created, so that the first sub-buffer can be initialized - * if necessary. In this case, prev_subbuf will be NULL. - */ - int (*subbuf_start) (struct rchan_buf *buf, - void *subbuf, - unsigned prev_subbuf_idx, - void *prev_subbuf); - - /* - * deliver - deliver a guaranteed full sub-buffer to client - * @buf: the channel buffer containing the sub-buffer - * @subbuf_idx: the sub-buffer's index - * @subbuf: the start of the new sub-buffer - * - * Only works if relay_commit is also used - */ - void (*deliver) (struct rchan_buf *buf, - unsigned subbuf_idx, - void *subbuf); - - /* - * buf_mapped - relayfs buffer mmap notification - * @buf: the channel buffer - * @filp: relayfs file pointer - * - * Called when a relayfs file is successfully mmapped - */ - void (*buf_mapped)(struct rchan_buf *buf, - struct file *filp); - - /* - * buf_unmapped - relayfs buffer unmap notification - * @buf: the channel buffer - * @filp: relayfs file pointer - * - * Called when a relayfs file is successfully unmapped - */ - void (*buf_unmapped)(struct rchan_buf *buf, - struct file *filp); - - /* - * buf_full - relayfs buffer full notification - * @buf: the channel channel buffer - * @subbuf_idx: the current sub-buffer's index - * @subbuf: the start of the current sub-buffer - * - * Called when a relayfs buffer becomes full - */ - void (*buf_full)(struct rchan_buf *buf, - unsigned subbuf_idx, - void *subbuf); -}; - -/* - * relayfs kernel API, fs/relayfs/relay.c - */ - -struct rchan *relay_open(const char *base_filename, - struct dentry *parent, - unsigned subbuf_size, - unsigned n_subbufs, - int overwrite, - struct rchan_callbacks *cb); -extern void relay_close(struct rchan *chan); -extern void relay_flush(struct rchan *chan); -extern void relay_subbufs_consumed(struct rchan *chan, - int cpu, - int subbufs_consumed); -extern void relay_reset(struct rchan *chan); -extern unsigned relay_switch_subbuf(struct rchan_buf *buf, - unsigned length); -extern void relay_commit(struct rchan_buf *buf, - void *reserved, - unsigned count); -extern struct dentry *relayfs_create_dir(const char *name, - struct dentry *parent); -extern int relayfs_remove_dir(struct dentry *dentry); - -/** - * relay_write - write data into the channel - * @chan: relay channel - * @data: data to be written - * @length: number of bytes to write - * - * Writes data into the current cpu's channel buffer. - * - * Protects the buffer by disabling interrupts. Use this - * if you might be logging from interrupt context. Try - * __relay_write() if you know you won't be logging from - * interrupt context. - */ -static inline void relay_write(struct rchan *chan, - const void *data, - unsigned length) -{ - unsigned long flags; - struct rchan_buf *buf; - - local_irq_save(flags); - buf = chan->buf[smp_processor_id()]; - if (unlikely(buf->offset + length > chan->subbuf_size)) - length = relay_switch_subbuf(buf, length); - memcpy(buf->data + buf->offset, data, length); - buf->offset += length; - local_irq_restore(flags); -} - -/** - * __relay_write - write data into the channel - * @chan: relay channel - * @data: data to be written - * @length: number of bytes to write - * - * Writes data into the current cpu's channel buffer. - * - * Protects the buffer by disabling preemption. Use - * relay_write() if you might be logging from interrupt - * context. - */ -static inline void __relay_write(struct rchan *chan, - const void *data, - unsigned length) -{ - struct rchan_buf *buf; - - buf = chan->buf[get_cpu()]; - if (unlikely(buf->offset + length > buf->chan->subbuf_size)) - length = relay_switch_subbuf(buf, length); - memcpy(buf->data + buf->offset, data, length); - buf->offset += length; - put_cpu(); -} - -/** - * relay_reserve - reserve slot in channel buffer - * @chan: relay channel - * @length: number of bytes to reserve - * - * Returns pointer to reserved slot, NULL if full. - * - * Reserves a slot in the current cpu's channel buffer. - * Does not protect the buffer at all - caller must provide - * appropriate synchronization. - */ -static inline void *relay_reserve(struct rchan *chan, unsigned length) -{ - void *reserved; - struct rchan_buf *buf = chan->buf[smp_processor_id()]; - - if (unlikely(buf->offset + length > buf->chan->subbuf_size)) { - length = relay_switch_subbuf(buf, length); - if (!length) - return NULL; - } - reserved = buf->data + buf->offset; - buf->offset += length; - - return reserved; -} - -/* - * exported relayfs file operations, fs/relayfs/inode.c - */ - -extern struct file_operations relayfs_file_operations; -extern int relayfs_open(struct inode *inode, struct file *filp); -extern unsigned int relayfs_poll(struct file *filp, poll_table *wait); -extern int relayfs_mmap(struct file *filp, struct vm_area_struct *vma); -extern int relayfs_release(struct inode *inode, struct file *filp); - -#endif /* _LINUX_RELAYFS_FS_H */ - diff --git a/runtime/relayfs/relay.c b/runtime/relayfs/relay.c deleted file mode 100644 index e35429ff..00000000 --- a/runtime/relayfs/relay.c +++ /dev/null @@ -1,545 +0,0 @@ -/* - * Public API and common code for RelayFS. - * - * See Documentation/filesystems/relayfs.txt for an overview of relayfs. - * - * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp - * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) - * - * This file is released under the GPL. - */ - -#include <linux/errno.h> -#include <linux/stddef.h> -#include <linux/slab.h> -#include <linux/module.h> -#include <linux/string.h> -#include "linux/relayfs_fs.h" -#include "relay.h" -#include "buffers.h" - -/** - * relay_buf_empty - boolean, is the channel buffer empty? - * @buf: channel buffer - * - * Returns 1 if the buffer is empty, 0 otherwise. - */ -int relay_buf_empty(struct rchan_buf *buf) -{ - int produced = atomic_read(&buf->subbufs_produced); - int consumed = atomic_read(&buf->subbufs_consumed); - - return (produced - consumed) ? 0 : 1; -} - -/** - * relay_buf_full - boolean, is the channel buffer full? - * @buf: channel buffer - * - * Returns 1 if the buffer is full, 0 otherwise. - */ -static inline int relay_buf_full(struct rchan_buf *buf) -{ - int produced, consumed; - - if (buf->chan->overwrite) - return 0; - - produced = atomic_read(&buf->subbufs_produced); - consumed = atomic_read(&buf->subbufs_consumed); - - return (produced - consumed > buf->chan->n_subbufs - 1) ? 1 : 0; -} - -/* - * High-level relayfs kernel API and associated functions. - */ - -/* - * rchan_callback implementations defining default channel behavior. Used - * in place of corresponding NULL values in client callback struct. - */ - -/* - * subbuf_start() default callback. Does nothing. - */ -static int subbuf_start_default_callback (struct rchan_buf *buf, - void *subbuf, - unsigned prev_subbuf_idx, - void *prev_subbuf) -{ - return 0; -} - -/* - * deliver() default callback. Does nothing. - */ -static void deliver_default_callback (struct rchan_buf *buf, - unsigned subbuf_idx, - void *subbuf) -{ -} - -/* - * buf_mapped() default callback. Does nothing. - */ -static void buf_mapped_default_callback(struct rchan_buf *buf, - struct file *filp) -{ -} - -/* - * buf_unmapped() default callback. Does nothing. - */ -static void buf_unmapped_default_callback(struct rchan_buf *buf, - struct file *filp) -{ -} - -/* - * buf_full() default callback. Does nothing. - */ -static void buf_full_default_callback(struct rchan_buf *buf, - unsigned subbuf_idx, - void *subbuf) -{ -} - -/* relay channel default callbacks */ -static struct rchan_callbacks default_channel_callbacks = { - .subbuf_start = subbuf_start_default_callback, - .deliver = deliver_default_callback, - .buf_mapped = buf_mapped_default_callback, - .buf_unmapped = buf_unmapped_default_callback, - .buf_full = buf_full_default_callback, -}; - -/** - * wakeup_readers - wake up readers waiting on a channel - * @private: the channel buffer - * - * This is the work function used to defer reader waking. The - * reason waking is deferred is that calling directly from write - * causes problems if you're writing from say the scheduler. - */ -static void wakeup_readers(void *private) -{ - struct rchan_buf *buf = private; - wake_up_interruptible(&buf->read_wait); -} - -/** - * get_next_subbuf - return next sub-buffer within channel buffer - * @buf: channel buffer - */ -static inline void *get_next_subbuf(struct rchan_buf *buf) -{ - void *next = buf->data + buf->chan->subbuf_size; - if (next >= buf->start + buf->chan->subbuf_size * buf->chan->n_subbufs) - next = buf->start; - - return next; -} - -/** - * __relay_reset - reset a channel buffer - * @buf: the channel buffer - * @init: 1 if this is a first-time initialization - * - * See relay_reset for description of effect. - */ -static inline void __relay_reset(struct rchan_buf *buf, int init) -{ - int i; - - if (init) { - init_waitqueue_head(&buf->read_wait); - kref_init(&buf->kref); - INIT_WORK(&buf->wake_readers, NULL, NULL); - } else { - cancel_delayed_work(&buf->wake_readers); - flush_scheduled_work(); - } - - atomic_set(&buf->subbufs_produced, 0); - atomic_set(&buf->subbufs_consumed, 0); - atomic_set(&buf->unfull, 0); - buf->finalized = 0; - buf->data = buf->start; - buf->offset = 0; - - for (i = 0; i < buf->chan->n_subbufs; i++) { - buf->padding[i] = 0; - buf->commit[i] = 0; - } - - buf->offset = buf->chan->cb->subbuf_start(buf, buf->data, 0, NULL); - buf->commit[0] = buf->offset; -} - -/** - * relay_reset - reset the channel - * @chan: the channel - * - * Returns 0 if successful, negative if not. - * - * This has the effect of erasing all data from all channel buffers - * and restarting the channel in its initial state. The buffers - * are not freed, so any mappings are still in effect. - * - * NOTE: Care should be taken that the channel isn't actually - * being used by anything when this call is made. - */ -void relay_reset(struct rchan *chan) -{ - int i; - - if (!chan) - return; - - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i]) - continue; - __relay_reset(chan->buf[i], 0); - } -} - -/** - * relay_open_buf - create a new channel buffer in relayfs - * - * Internal - used by relay_open(). - */ -static struct rchan_buf *relay_open_buf(struct rchan *chan, - const char *filename, - struct dentry *parent) -{ - struct rchan_buf *buf; - struct dentry *dentry; - - /* Create file in fs */ - dentry = relayfs_create_file(filename, parent, S_IRUSR, chan); - if (!dentry) - return NULL; - - buf = RELAYFS_I(dentry->d_inode)->buf; - buf->dentry = dentry; - __relay_reset(buf, 1); - - return buf; -} - -/** - * relay_close_buf - close a channel buffer - * @buf: channel buffer - * - * Marks the buffer finalized and restores the default callbacks. - * The channel buffer and channel buffer data structure are then freed - * automatically when the last reference is given up. - */ -static inline void relay_close_buf(struct rchan_buf *buf) -{ - buf->finalized = 1; - buf->chan->cb = &default_channel_callbacks; - cancel_delayed_work(&buf->wake_readers); - flush_scheduled_work(); - kref_put(&buf->kref, relay_remove_buf); -} - -static inline void setup_callbacks(struct rchan *chan, - struct rchan_callbacks *cb) -{ - if (!cb) { - chan->cb = &default_channel_callbacks; - return; - } - - if (!cb->subbuf_start) - cb->subbuf_start = subbuf_start_default_callback; - if (!cb->deliver) - cb->deliver = deliver_default_callback; - if (!cb->buf_mapped) - cb->buf_mapped = buf_mapped_default_callback; - if (!cb->buf_unmapped) - cb->buf_unmapped = buf_unmapped_default_callback; - if (!cb->buf_full) - cb->buf_full = buf_full_default_callback; - chan->cb = cb; -} - -/** - * relay_open - create a new relayfs channel - * @base_filename: base name of files to create - * @parent: dentry of parent directory, NULL for root directory - * @subbuf_size: size of sub-buffers - * @n_subbufs: number of sub-buffers - * @overwrite: overwrite buffer when full? - * @cb: client callback functions - * - * Returns channel pointer if successful, NULL otherwise. - * - * Creates a channel buffer for each cpu using the sizes and - * attributes specified. The created channel buffer files - * will be named base_filename0...base_filenameN-1. File - * permissions will be S_IRUSR. - */ -struct rchan *relay_open(const char *base_filename, - struct dentry *parent, - unsigned subbuf_size, - unsigned n_subbufs, - int overwrite, - struct rchan_callbacks *cb) -{ - int i; - struct rchan *chan; - char *tmpname; - - if (!base_filename) - return NULL; - - if (!(subbuf_size && n_subbufs)) - return NULL; - - chan = kcalloc(1, sizeof(struct rchan), GFP_KERNEL); - if (!chan) - return NULL; - - chan->version = RELAYFS_CHANNEL_VERSION; - chan->overwrite = overwrite; - chan->n_subbufs = n_subbufs; - chan->subbuf_size = subbuf_size; - chan->alloc_size = FIX_SIZE(subbuf_size * n_subbufs); - setup_callbacks(chan, cb); - kref_init(&chan->kref); - - tmpname = kmalloc(NAME_MAX + 1, GFP_KERNEL); - if (!tmpname) - goto free_chan; - - for_each_online_cpu(i) { - sprintf(tmpname, "%s%d", base_filename, i); - chan->buf[i] = relay_open_buf(chan, tmpname, parent); - if (!chan->buf[i]) - goto free_bufs; - } - - kfree(tmpname); - return chan; - -free_bufs: - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i]) - break; - relay_close_buf(chan->buf[i]); - } - kfree(tmpname); - -free_chan: - kref_put(&chan->kref, relay_destroy_channel); - return NULL; -} - -/** - * deliver_check - deliver a guaranteed full sub-buffer if applicable - */ -static inline void deliver_check(struct rchan_buf *buf, - unsigned subbuf_idx) -{ - void *subbuf; - unsigned full = buf->chan->subbuf_size - buf->padding[subbuf_idx]; - - if (buf->commit[subbuf_idx] == full) { - subbuf = buf->start + subbuf_idx * buf->chan->subbuf_size; - buf->chan->cb->deliver(buf, subbuf_idx, subbuf); - } -} - -/** - * do_switch - change subbuf pointer and do related bookkeeping - */ -static inline void do_switch(struct rchan_buf *buf, unsigned new, unsigned old) -{ - unsigned start = 0; - void *old_data = buf->start + old * buf->chan->subbuf_size; - - buf->data = get_next_subbuf(buf); - buf->padding[new] = 0; - start = buf->chan->cb->subbuf_start(buf, buf->data, old, old_data); - buf->offset = buf->commit[new] = start; -} - -/** - * relay_switch_subbuf - switch to a new sub-buffer - * @buf: channel buffer - * @length: size of current event - * - * Returns either the length passed in or 0 if full. - - * Performs sub-buffer-switch tasks such as invoking callbacks, - * updating padding counts, waking up readers, etc. - */ -unsigned relay_switch_subbuf(struct rchan_buf *buf, unsigned length) -{ - int new, old, produced = atomic_read(&buf->subbufs_produced); - unsigned padding; - - if (unlikely(length > buf->chan->subbuf_size)) - goto toobig; - - if (unlikely(atomic_read(&buf->unfull))) { - atomic_set(&buf->unfull, 0); - new = produced % buf->chan->n_subbufs; - old = (produced - 1) % buf->chan->n_subbufs; - do_switch(buf, new, old); - return 0; - } - - if (unlikely(relay_buf_full(buf))) - return 0; - - old = produced % buf->chan->n_subbufs; - padding = buf->chan->subbuf_size - buf->offset; - buf->padding[old] = padding; - deliver_check(buf, old); - buf->offset = buf->chan->subbuf_size; - atomic_inc(&buf->subbufs_produced); - - if (waitqueue_active(&buf->read_wait)) { - PREPARE_WORK(&buf->wake_readers, wakeup_readers, buf); - schedule_delayed_work(&buf->wake_readers, 1); - } - - if (unlikely(relay_buf_full(buf))) { - void *old_data = buf->start + old * buf->chan->subbuf_size; - buf->chan->cb->buf_full(buf, old, old_data); - return 0; - } - - new = (produced + 1) % buf->chan->n_subbufs; - do_switch(buf, new, old); - - if (unlikely(length + buf->offset > buf->chan->subbuf_size)) - goto toobig; - - return length; - - toobig: - printk(KERN_WARNING "relayfs: event too large (%u)\n", length); - WARN_ON(1); - return 0; -} - -/** - * relay_commit - add count bytes to a sub-buffer's commit count - * @buf: channel buffer - * @reserved: reserved address associated with commit - * @count: number of bytes committed - * - * Invokes deliver() callback if sub-buffer is completely written. - */ -void relay_commit(struct rchan_buf *buf, - void *reserved, - unsigned count) -{ - unsigned offset, subbuf_idx; - - offset = reserved - buf->start; - subbuf_idx = offset / buf->chan->subbuf_size; - buf->commit[subbuf_idx] += count; - deliver_check(buf, subbuf_idx); -} - -/** - * relay_subbufs_consumed - update the buffer's sub-buffers-consumed count - * @chan: the channel - * @cpu: the cpu associated with the channel buffer to update - * @subbufs_consumed: number of sub-buffers to add to current buf's count - * - * Adds to the channel buffer's consumed sub-buffer count. - * subbufs_consumed should be the number of sub-buffers newly consumed, - * not the total consumed. - * - * NOTE: kernel clients don't need to call this function if the channel - * mode is 'overwrite'. - */ -void relay_subbufs_consumed(struct rchan *chan, int cpu, int subbufs_consumed) -{ - int produced, consumed; - struct rchan_buf *buf; - - if (!chan) - return; - - if (cpu >= NR_CPUS || !chan->buf[cpu]) - return; - - buf = chan->buf[cpu]; - if (relay_buf_full(buf)) - atomic_set(&buf->unfull, 1); - - atomic_add(subbufs_consumed, &buf->subbufs_consumed); - produced = atomic_read(&buf->subbufs_produced); - consumed = atomic_read(&buf->subbufs_consumed); - if (consumed > produced) - atomic_set(&buf->subbufs_consumed, produced); -} - -/** - * relay_destroy_channel - free the channel struct - * - * Should only be called from kref_put(). - */ -void relay_destroy_channel(struct kref *kref) -{ - struct rchan *chan = container_of(kref, struct rchan, kref); - kfree(chan); -} - -/** - * relay_close - close the channel - * @chan: the channel - * - * Closes all channel buffers and frees the channel. - */ -void relay_close(struct rchan *chan) -{ - int i; - - if (!chan) - return; - - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i]) - continue; - relay_close_buf(chan->buf[i]); - } - - kref_put(&chan->kref, relay_destroy_channel); -} - -/** - * relay_flush - close the channel - * @chan: the channel - * - * Flushes all channel buffers i.e. forces buffer switch. - */ -void relay_flush(struct rchan *chan) -{ - int i; - - if (!chan) - return; - - for (i = 0; i < NR_CPUS; i++) { - if (!chan->buf[i]) - continue; - relay_switch_subbuf(chan->buf[i], 0); - } -} - -EXPORT_SYMBOL_GPL(relay_open); -EXPORT_SYMBOL_GPL(relay_close); -EXPORT_SYMBOL_GPL(relay_flush); -EXPORT_SYMBOL_GPL(relay_reset); -EXPORT_SYMBOL_GPL(relay_subbufs_consumed); -EXPORT_SYMBOL_GPL(relay_commit); -EXPORT_SYMBOL_GPL(relay_switch_subbuf); diff --git a/runtime/relayfs/relay.h b/runtime/relayfs/relay.h deleted file mode 100644 index 703503fa..00000000 --- a/runtime/relayfs/relay.h +++ /dev/null @@ -1,12 +0,0 @@ -#ifndef _RELAY_H -#define _RELAY_H - -struct dentry *relayfs_create_file(const char *name, - struct dentry *parent, - int mode, - struct rchan *chan); -extern int relayfs_remove(struct dentry *dentry); -extern int relay_buf_empty(struct rchan_buf *buf); -extern void relay_destroy_channel(struct kref *kref); - -#endif /* _RELAY_H */ diff --git a/runtime/relayfs/relayfs.txt b/runtime/relayfs/relayfs.txt deleted file mode 100644 index 6d973063..00000000 --- a/runtime/relayfs/relayfs.txt +++ /dev/null @@ -1,214 +0,0 @@ - -relayfs - a high-speed data relay filesystem -============================================ - -relayfs is a filesystem designed to provide an efficient mechanism for -tools and facilities to relay large and potentially sustained streams -of data from kernel space to user space. - -The main abstraction of relayfs is the 'channel'. A channel consists -of a set of per-cpu kernel buffers each represented by a file in the -relayfs filesystem. Kernel clients write into a channel using -efficient write functions which automatically log to the current cpu's -channel buffer. User space applications mmap() the per-cpu files and -retrieve the data as it becomes available. - -The format of the data logged into the channel buffers is completely -up to the relayfs client; relayfs does however provide hooks which -allow clients to impose some stucture on the buffer data. Nor does -relayfs implement any form of data filtering - this also is left to -the client. The purpose is to keep relayfs as simple as possible. - -This document provides an overview of the relayfs API. The details of -the function parameters are documented along with the functions in the -filesystem code - please see that for details. - - -The relayfs user space API -========================== - -relayfs implements basic file operations for user space access to -relayfs channel buffer data. Here are the file operations that are -available and some comments regarding their behavior: - -open() enables user to open an _existing_ buffer. - -mmap() results in channel buffer being mapped into the caller's - memory space. - -poll() POLLIN/POLLRDNORM/POLLERR supported. User applications are - notified when sub-buffer boundaries are crossed. - -close() decrements the channel buffer's refcount. When the refcount - reaches 0 i.e. when no process or kernel client has the buffer - open, the channel buffer is freed. - - -In order for a user application to make use of relayfs files, the -relayfs filesystem must be mounted. For example, - - mount -t relayfs relayfs /mnt/relay - -NOTE: relayfs doesn't need to be mounted for kernel clients to create - or use channels - it only needs to be mounted when user space - applications need access to the buffer data. - - -The relayfs kernel API -====================== - -Here's a summary of the API relayfs provides to in-kernel clients: - - - channel management functions: - - relay_open(base_filename, parent, subbuf_size, n_subbufs, - overwrite, callbacks) - relay_close(chan) - relay_flush(chan) - relay_reset(chan) - relayfs_create_dir(name, parent) - relayfs_remove_dir(dentry) - relay_commit(buf, reserved, count) - relay_subbufs_consumed(chan, cpu, subbufs_consumed) - - write functions: - - relay_write(chan, data, length) - __relay_write(chan, data, length) - relay_reserve(chan, length) - - callbacks: - - subbuf_start(buf, subbuf, prev_subbuf_idx, prev_subbuf) - deliver(buf, subbuf_idx, subbuf) - buf_mapped(buf, filp) - buf_unmapped(buf, filp) - buf_full(buf, subbuf_idx) - - -A relayfs channel is made of up one or more per-cpu channel buffers, -each implemented as a circular buffer subdivided into one or more -sub-buffers. - -relay_open() is used to create a channel, along with its per-cpu -channel buffers. Each channel buffer will have an associated file -created for it in the relayfs filesystem, which can be opened and -mmapped from user space if desired. The files are named -basename0...basenameN-1 where N is the number of online cpus, and by -default will be created in the root of the filesystem. If you want a -directory structure to contain your relayfs files, you can create it -with relayfs_create_dir() and pass the parent directory to -relay_open(). Clients are responsible for cleaning up any directory -structure they create when the channel is closed - use -relayfs_remove_dir() for that. - -The total size of each per-cpu buffer is calculated by multiplying the -number of sub-buffers by the sub-buffer size passed into relay_open(). -The idea behind sub-buffers is that they're basically an extension of -double-buffering to N buffers, and they also allow applications to -easily implement random-access-on-buffer-boundary schemes, which can -be important for some high-volume applications. The number and size -of sub-buffers is completely dependent on the application and even for -the same application, different conditions will warrant different -values for these parameters at different times. Typically, the right -values to use are best decided after some experimentation; in general, -though, it's safe to assume that having only 1 sub-buffer is a bad -idea - you're guaranteed to either overwrite data or lose events -depending on the channel mode being used. - -relayfs channels can be opened in either of two modes - 'overwrite' or -'no-overwrite'. In overwrite mode, writes continuously cycle around -the buffer and will never fail, but will unconditionally overwrite old -data regardless of whether it's actually been consumed. In -no-overwrite mode, writes will fail i.e. data will be lost, if the -number of unconsumed sub-buffers equals the total number of -sub-buffers in the channel. In this mode, the client is reponsible -for notifying relayfs when sub-buffers have been consumed via -relay_subbufs_consumed(). A full buffer will become 'unfull' and -logging will continue once the client calls relay_subbufs_consumed() -again. When a buffer becomes full, the buf_full() callback is invoked -to notify the client. In both modes, the subbuf_start() callback will -notify the client whenever a sub-buffer boundary is crossed. This can -be used to write header information into the new sub-buffer or fill in -header information reserved in the previous sub-buffer. One piece of -information that's useful to save in a reserved header slot is the -number of bytes of 'padding' for a sub-buffer, which is the amount of -unused space at the end of a sub-buffer. The padding count for each -sub-buffer is contained in an array in the rchan_buf struct passed -into the subbuf_start() callback: rchan_buf->padding[prev_subbuf_idx] -can be used to to get the padding for the just-finished sub-buffer. -subbuf_start() is also called for the first sub-buffer in each channel -buffer when the channel is created. The mode is specified to -relay_open() using the overwrite parameter. - -kernel clients write data into the current cpu's channel buffer using -relay_write() or __relay_write(). relay_write() is the main logging -function - it uses local_irqsave() to protect the buffer and should be -used if you might be logging from interrupt context. If you know -you'll never be logging from interrupt context, you can use -__relay_write(), which only disables preemption. These functions -don't return a value, so you can't determine whether or not they -failed - the assumption is that you wouldn't want to check a return -value in the fast logging path anyway, and that they'll always succeed -unless the buffer is full and in no-overwrite mode, in which case -you'll be notified via the buf_full() callback. - -relay_reserve() is used to reserve a slot in a channel buffer which -can be written to later. This would typically be used in applications -that need to write directly into a channel buffer without having to -stage data in a temporary buffer beforehand. Because the actual write -may not happen immediately after the slot is reserved, applications -using relay_reserve() can call relay_commit() to notify relayfs when -the slot has actually been written. When all the reserved slots have -been committed, the deliver() callback is invoked to notify the client -that a guaranteed full sub-buffer has been produced. Because the -write is under control of the client and is separated from the -reserve, relay_reserve() doesn't protect the buffer at all - it's up -to the client to provide the appropriate synchronization when using -relay_reserve(). - -The client calls relay_close() when it's finished using the channel. -The channel and its associated buffers are destroyed when there are no -longer any references to any of the channel buffers. relay_flush() -forces a sub-buffer switch on all the channel buffers, and can be used -to finalize and process the last sub-buffers before the channel is -closed. - -Some applications may want to keep a channel around and re-use it -rather than open and close a new channel for each use. relay_reset() -can be used for this purpose - it resets a channel to its initial -state without reallocating channel buffer memory or destroying -existing mappings. It should however only be called when it's safe to -do so i.e. when the channel isn't currently being written to. - -Finally, there are a couple of utility callbacks that can be used for -different purposes. buf_mapped() is called whenever a channel buffer -is mmapped from user space and buf_unmapped() is called when it's -unmapped. The client can use this notification to trigger actions -within the kernel application, such as enabling/disabling logging to -the channel. - - -Resources -========= - -For news, example code, mailing list, etc. see the relayfs homepage: - - http://relayfs.sourceforge.net - - -Credits -======= - -The ideas and specs for relayfs came about as a result of discussions -on tracing involving the following: - -Michel Dagenais <michel.dagenais@polymtl.ca> -Richard Moore <richardj_moore@uk.ibm.com> -Bob Wisniewski <bob@watson.ibm.com> -Karim Yaghmour <karim@opersys.com> -Tom Zanussi <zanussi@us.ibm.com> - -Also thanks to Hubertus Franke for a lot of useful suggestions and bug -reports. |