diff options
| author | Christoph Lameter <christoph@lameter.com> | 2005-06-24 23:13:50 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-25 17:10:13 -0700 |
| commit | 3e1d1d28d99dabe63c64f7f40f1ca1d646de1f73 (patch) | |
| tree | d1e7c1e2e8902072042aefc3a7976b271cf76021 /Documentation/power | |
| parent | b3e112bcc19abd8e9657dca34a87316786e096f3 (diff) | |
| download | lwn-3e1d1d28d99dabe63c64f7f40f1ca1d646de1f73.tar.gz lwn-3e1d1d28d99dabe63c64f7f40f1ca1d646de1f73.zip | |
[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 <christoph@lameter.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation/power')
| -rw-r--r-- | Documentation/power/kernel_threads.txt | 3 | ||||
| -rw-r--r-- | Documentation/power/swsusp.txt | 3 |
2 files changed, 2 insertions, 4 deletions
diff --git a/Documentation/power/kernel_threads.txt b/Documentation/power/kernel_threads.txt index 60b548105edf..fb57784986b1 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 c7c3459fde43..4e1627cc5b51 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. |