diff options
| author | Rafael J. Wysocki <rjw@sisk.pl> | 2007-07-17 04:03:35 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-17 10:23:02 -0700 |
| commit | 831441862956fffa17b9801db37e6ea1650b0f69 (patch) | |
| tree | b0334921341f8f1734bdd3243de76d676329d21c /drivers/char | |
| parent | 787d2214c19bcc9b6ac48af0ce098277a801eded (diff) | |
Freezer: make kernel threads nonfreezable by default
Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves. This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.
It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.
The patch causes all kernel threads to be nonfreezable by default (ie. to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE. It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear. Additionally, it updates documentation to
describe the freezing of tasks more accurately.
[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/apm-emulation.c | 12 | ||||
| -rw-r--r-- | drivers/char/hvc_console.c | 1 |
2 files changed, 2 insertions, 11 deletions
diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c index 179c7a3b6e7..ec116df919d 100644 --- a/drivers/char/apm-emulation.c +++ b/drivers/char/apm-emulation.c @@ -20,6 +20,7 @@ #include <linux/sched.h> #include <linux/pm.h> #include <linux/apm-emulation.h> +#include <linux/freezer.h> #include <linux/device.h> #include <linux/kernel.h> #include <linux/list.h> @@ -329,13 +330,8 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg) /* * Wait for the suspend/resume to complete. If there * are pending acknowledges, we wait here for them. - * - * Note: we need to ensure that the PM subsystem does - * not kick us out of the wait when it suspends the - * threads. */ flags = current->flags; - current->flags |= PF_NOFREEZE; wait_event(apm_suspend_waitqueue, as->suspend_state == SUSPEND_DONE); @@ -365,13 +361,8 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg) /* * Wait for the suspend/resume to complete. If there * are pending acknowledges, we wait here for them. - * - * Note: we need to ensure that the PM subsystem does - * not kick us out of the wait when it suspends the - * threads. */ flags = current->flags; - current->flags |= PF_NOFREEZE; wait_event_interruptible(apm_suspend_waitqueue, as->suspend_state == SUSPEND_DONE); @@ -598,7 +589,6 @@ static int __init apm_init(void) kapmd_tsk = NULL; return ret; } - kapmd_tsk->flags |= PF_NOFREEZE; wake_up_process(kapmd_tsk); #ifdef CONFIG_PROC_FS diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c index b3ab42e0dd4..83c1151ec7a 100644 --- a/drivers/char/hvc_console.c +++ b/drivers/char/hvc_console.c @@ -679,6 +679,7 @@ static int khvcd(void *unused) int poll_mask; struct hvc_struct *hp; + set_freezable(); __set_current_state(TASK_RUNNING); do { poll_mask = 0; |