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| author | Tejun Heo <tj@kernel.org> | 2011-11-21 12:32:23 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2011-11-21 12:32:23 -0800 |
| commit | 8a32c441c1609f80e55df75422324a1151208f40 (patch) | |
| tree | 73884b06cc2db3ea155af9a88815bb5105a4473e /include/linux/freezer.h | |
| parent | a0acae0e886d44bd5ce6d2f173c1ace0fcf0d9f6 (diff) | |
| download | op-kernel-dev-8a32c441c1609f80e55df75422324a1151208f40.zip op-kernel-dev-8a32c441c1609f80e55df75422324a1151208f40.tar.gz | |
freezer: implement and use kthread_freezable_should_stop()
Writeback and thinkpad_acpi have been using thaw_process() to prevent
deadlock between the freezer and kthread_stop(); unfortunately, this
is inherently racy - nothing prevents freezing from happening between
thaw_process() and kthread_stop().
This patch implements kthread_freezable_should_stop() which enters
refrigerator if necessary but is guaranteed to return if
kthread_stop() is invoked. Both thaw_process() users are converted to
use the new function.
Note that this deadlock condition exists for many of freezable
kthreads. They need to be converted to use the new should_stop or
freezable workqueue.
Tested with synthetic test case.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'include/linux/freezer.h')
| -rw-r--r-- | include/linux/freezer.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 7a9427e..d02b784 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -47,7 +47,7 @@ static inline bool should_send_signal(struct task_struct *p) /* Takes and releases task alloc lock using task_lock() */ extern int thaw_process(struct task_struct *p); -extern bool __refrigerator(void); +extern bool __refrigerator(bool check_kthr_stop); extern int freeze_processes(void); extern int freeze_kernel_threads(void); extern void thaw_processes(void); @@ -57,7 +57,7 @@ static inline bool try_to_freeze(void) might_sleep(); if (likely(!freezing(current))) return false; - return __refrigerator(); + return __refrigerator(false); } extern bool freeze_task(struct task_struct *p, bool sig_only); @@ -180,7 +180,7 @@ static inline void set_freeze_flag(struct task_struct *p) {} static inline void clear_freeze_flag(struct task_struct *p) {} static inline int thaw_process(struct task_struct *p) { return 1; } -static inline bool __refrigerator(void) { return false; } +static inline bool __refrigerator(bool check_kthr_stop) { return false; } static inline int freeze_processes(void) { return -ENOSYS; } static inline int freeze_kernel_threads(void) { return -ENOSYS; } static inline void thaw_processes(void) {} |
