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authorTejun Heo <tj@kernel.org>2011-11-21 12:32:22 -0800
committerTejun Heo <tj@kernel.org>2011-11-21 12:32:22 -0800
commita0acae0e886d44bd5ce6d2f173c1ace0fcf0d9f6 (patch)
tree0b763388360a5a9043986e1f2201e43df74ebc46 /Documentation/power
parent3a7cbd50f74907580eb47a8d08e1f29741b81abf (diff)
downloadop-kernel-dev-a0acae0e886d44bd5ce6d2f173c1ace0fcf0d9f6.zip
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freezer: unexport refrigerator() and update try_to_freeze() slightly
There is no reason to export two functions for entering the refrigerator. Calling refrigerator() instead of try_to_freeze() doesn't save anything noticeable or removes any race condition. * Rename refrigerator() to __refrigerator() and make it return bool indicating whether it scheduled out for freezing. * Update try_to_freeze() to return bool and relay the return value of __refrigerator() if freezing(). * Convert all refrigerator() users to try_to_freeze(). * Update documentation accordingly. * While at it, add might_sleep() to try_to_freeze(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Samuel Ortiz <samuel@sortiz.org> Cc: Chris Mason <chris.mason@oracle.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp> Cc: Christoph Hellwig <hch@infradead.org>
Diffstat (limited to 'Documentation/power')
-rw-r--r--Documentation/power/freezing-of-tasks.txt12
1 files changed, 6 insertions, 6 deletions
diff --git a/Documentation/power/freezing-of-tasks.txt b/Documentation/power/freezing-of-tasks.txt
index 587e082..3ab9fbd 100644
--- a/Documentation/power/freezing-of-tasks.txt
+++ b/Documentation/power/freezing-of-tasks.txt
@@ -21,7 +21,7 @@ freeze_processes() (defined in kernel/power/process.c) is called. It executes
try_to_freeze_tasks() that sets TIF_FREEZE for all of the freezable tasks and
either wakes them up, if they are kernel threads, or sends fake signals to them,
if they are user space processes. A task that has TIF_FREEZE set, should react
-to it by calling the function called refrigerator() (defined in
+to it by calling the function called __refrigerator() (defined in
kernel/freezer.c), which sets the task's PF_FROZEN flag, changes its state
to TASK_UNINTERRUPTIBLE and makes it loop until PF_FROZEN is cleared for it.
Then, we say that the task is 'frozen' and therefore the set of functions
@@ -29,10 +29,10 @@ handling this mechanism is referred to as 'the freezer' (these functions are
defined in kernel/power/process.c, kernel/freezer.c & include/linux/freezer.h).
User space processes are generally frozen before kernel threads.
-It is not recommended to call refrigerator() directly. Instead, it is
-recommended to use the try_to_freeze() function (defined in
-include/linux/freezer.h), that checks the task's TIF_FREEZE flag and makes the
-task enter refrigerator() if the flag is set.
+__refrigerator() must not be called directly. Instead, use the
+try_to_freeze() function (defined in include/linux/freezer.h), that checks
+the task's TIF_FREEZE flag and makes the task enter __refrigerator() if the
+flag is set.
For user space processes try_to_freeze() is called automatically from the
signal-handling code, but the freezable kernel threads need to call it
@@ -61,7 +61,7 @@ wait_event_freezable() and wait_event_freezable_timeout() macros.
After the system memory state has been restored from a hibernation image and
devices have been reinitialized, the function thaw_processes() is called in
order to clear the PF_FROZEN flag for each frozen task. Then, the tasks that
-have been frozen leave refrigerator() and continue running.
+have been frozen leave __refrigerator() and continue running.
III. Which kernel threads are freezable?
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