From 3e1d1d28d99dabe63c64f7f40f1ca1d646de1f73 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Fri, 24 Jun 2005 23:13:50 -0700 Subject: [PATCH] Cleanup patch for process freezing 1. Establish a simple API for process freezing defined in linux/include/sched.h: frozen(process) Check for frozen process freezing(process) Check if a process is being frozen freeze(process) Tell a process to freeze (go to refrigerator) thaw_process(process) Restart process frozen_process(process) Process is frozen now 2. Remove all references to PF_FREEZE and PF_FROZEN from all kernel sources except sched.h 3. Fix numerous locations where try_to_freeze is manually done by a driver 4. Remove the argument that is no longer necessary from two function calls. 5. Some whitespace cleanup 6. Clear potential race in refrigerator (provides an open window of PF_FREEZE cleared before setting PF_FROZEN, recalc_sigpending does not check PF_FROZEN). This patch does not address the problem of freeze_processes() violating the rule that a task may only modify its own flags by setting PF_FREEZE. This is not clean in an SMP environment. freeze(process) is therefore not SMP safe! Signed-off-by: Christoph Lameter Signed-off-by: Linus Torvalds --- Documentation/power/kernel_threads.txt | 3 +-- Documentation/power/swsusp.txt | 3 +-- 2 files changed, 2 insertions(+), 4 deletions(-) (limited to 'Documentation') diff --git a/Documentation/power/kernel_threads.txt b/Documentation/power/kernel_threads.txt index 60b548105ed..fb57784986b 100644 --- a/Documentation/power/kernel_threads.txt +++ b/Documentation/power/kernel_threads.txt @@ -12,8 +12,7 @@ refrigerator. Code to do this looks like this: do { hub_events(); wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list)); - if (current->flags & PF_FREEZE) - refrigerator(PF_FREEZE); + try_to_freeze(); } while (!signal_pending(current)); from drivers/usb/core/hub.c::hub_thread() diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt index c7c3459fde4..4e1627cc5b5 100644 --- a/Documentation/power/swsusp.txt +++ b/Documentation/power/swsusp.txt @@ -164,8 +164,7 @@ place where the thread is safe to be frozen (no kernel semaphores should be held at that point and it must be safe to sleep there), and add: - if (current->flags & PF_FREEZE) - refrigerator(PF_FREEZE); + try_to_freeze(); If the thread is needed for writing the image to storage, you should instead set the PF_NOFREEZE process flag when creating the thread. -- cgit