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/* -*- linux-c -*-
*
* relay.c - staprun relayfs functions
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*
* Copyright (C) 2007 Red Hat Inc.
*/
#include "staprun.h"
int out_fd[NR_CPUS];
static pthread_t reader[NR_CPUS];
static int relay_fd[NR_CPUS];
static int bulkmode = 0;
static volatile int stop_threads = 0;
/*
* ppoll exists in glibc >= 2.4
*/
#if (__GLIBC__ < 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ < 4))
#define NEED_PPOLL
#endif
#ifdef NEED_PPOLL
static int ppoll(struct pollfd *fds, nfds_t nfds,
const struct timespec *timeout, const sigset_t *sigmask)
{
sigset_t origmask;
int ready;
int tim;
if (timeout == NULL)
tim = -1;
else
tim = timeout->tv_sec * 1000 + timeout->tv_nsec / 1000000;
sigprocmask(SIG_SETMASK, sigmask, &origmask);
ready = poll(fds, nfds, tim);
sigprocmask(SIG_SETMASK, &origmask, NULL);
return ready;
}
#endif
/**
* reader_thread - per-cpu channel buffer reader
*/
static void empty_handler(int __attribute__((unused)) sig) { /* do nothing */ }
static void *reader_thread(void *data)
{
char buf[131072];
int rc, cpu = (int)(long)data;
struct pollfd pollfd;
struct timespec tim = {.tv_sec=0, .tv_nsec=200000000}, *timeout = &tim;
sigset_t sigs;
struct sigaction sa;
sigemptyset(&sigs);
sigaddset(&sigs,SIGUSR2);
pthread_sigmask(SIG_BLOCK, &sigs, NULL);
sigfillset(&sigs);
sigdelset(&sigs,SIGUSR2);
sa.sa_handler = empty_handler;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGUSR2, &sa, NULL);
if (bulkmode) {
cpu_set_t cpu_mask;
CPU_ZERO(&cpu_mask);
CPU_SET(cpu, &cpu_mask);
if( sched_setaffinity( 0, sizeof(cpu_mask), &cpu_mask ) < 0 ) {
perror("sched_setaffinity");
}
#ifdef NEED_PPOLL
/* Without a real ppoll, there is a small race condition that could */
/* block ppoll(). So use a timeout to prevent that. */
timeout->tv_sec = 10;
timeout->tv_nsec = 0;
#else
timeout = NULL;
#endif
}
pollfd.fd = relay_fd[cpu];
pollfd.events = POLLIN;
do {
rc = ppoll(&pollfd, 1, timeout, &sigs);
if (rc < 0) {
dbug(3, "cpu=%d poll=%d errno=%d\n", cpu, rc, errno);
if (errno != EINTR) {
fprintf(stderr, "poll error: %s\n",strerror(errno));
return(NULL);
}
stop_threads = 1;
}
while ((rc = read(relay_fd[cpu], buf, sizeof(buf))) > 0) {
if (write(out_fd[cpu], buf, rc) != rc) {
fprintf(stderr, "Couldn't write to output fd %d for cpu %d, exiting: errcode = %d: %s\n",
out_fd[cpu], cpu, errno, strerror(errno));
return(NULL);
}
}
} while (!stop_threads);
dbug(3, "exiting thread %d\n", cpu);
return(NULL);
}
/**
* init_relayfs - create files and threads for relayfs processing
*
* Returns 0 if successful, negative otherwise
*/
int init_relayfs(void)
{
int i;
struct statfs st;
char buf[128], relay_filebase[128];
dbug(1, "initializing relayfs\n");
reader[0] = (pthread_t)0;
relay_fd[0] = 0;
out_fd[0] = 0;
if (statfs("/sys/kernel/debug", &st) == 0 && (int) st.f_type == (int) DEBUGFS_MAGIC)
sprintf(relay_filebase, "/sys/kernel/debug/systemtap/%s", modname);
else {
fprintf(stderr,"Cannot find relayfs or debugfs mount point.\n");
return -1;
}
for (i = 0; i < NR_CPUS; i++) {
sprintf(buf, "%s/trace%d", relay_filebase, i);
dbug(2, "attempting to open %s\n", buf);
relay_fd[i] = open(buf, O_RDONLY | O_NONBLOCK);
if (relay_fd[i] < 0)
break;
}
ncpus = i;
dbug(2, "ncpus=%d\n", ncpus);
if (ncpus == 0) {
err("couldn't open %s.\n", buf);
return -1;
}
if (ncpus > 1)
bulkmode = 1;
if (bulkmode) {
for (i = 0; i < ncpus; i++) {
if (outfile_name) {
/* special case: for testing we sometimes want to write to /dev/null */
if (strcmp(outfile_name, "/dev/null") == 0)
strcpy(buf, outfile_name);
else
sprintf(buf, "%s_%d", outfile_name, i);
} else
sprintf(buf, "stpd_cpu%d", i);
out_fd[i] = open (buf, O_CREAT|O_TRUNC|O_WRONLY, 0666);
if (out_fd[i] < 0) {
fprintf(stderr, "ERROR: couldn't open output file %s.\n", buf);
return -1;
}
}
} else {
/* stream mode */
if (outfile_name) {
out_fd[0] = open (outfile_name, O_CREAT|O_TRUNC|O_WRONLY, 0666);
if (out_fd[0] < 0) {
fprintf(stderr, "ERROR: couldn't open output file %s.\n", outfile_name);
return -1;
}
} else
out_fd[0] = STDOUT_FILENO;
}
dbug(2, "starting threads\n");
for (i = 0; i < ncpus; i++) {
if (pthread_create(&reader[i], NULL, reader_thread, (void *)(long)i) < 0) {
fprintf(stderr, "failed to create thread\n");
perror("Error creating thread");
return -1;
}
}
return 0;
}
void close_relayfs(void)
{
int i;
stop_threads = 1;
dbug(2, "closing\n");
for (i = 0; i < ncpus; i++) {
if (reader[i])
pthread_kill(reader[i], SIGUSR2);
else
break;
}
for (i = 0; i < ncpus; i++) {
if (reader[i])
pthread_join(reader[i], NULL);
else
break;
}
for (i = 0; i < ncpus; i++) {
if (relay_fd[i] >= 0)
close(relay_fd[i]);
else
break;
}
dbug(2, "done\n");
}
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