From 7dfb71030f7636a0d65200158113c37764552f93 Mon Sep 17 00:00:00 2001 From: Nigel Cunningham Date: Wed, 6 Dec 2006 20:34:23 -0800 Subject: [PATCH] Add include/linux/freezer.h and move definitions from sched.h Move process freezing functions from include/linux/sched.h to freezer.h, so that modifications to the freezer or the kernel configuration don't require recompiling just about everything. [akpm@osdl.org: fix ueagle driver] Signed-off-by: Nigel Cunningham Cc: "Rafael J. Wysocki" Cc: Pavel Machek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/freezer.h | 84 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) create mode 100644 include/linux/freezer.h (limited to 'include/linux/freezer.h') diff --git a/include/linux/freezer.h b/include/linux/freezer.h new file mode 100644 index 00000000000..266373f7444 --- /dev/null +++ b/include/linux/freezer.h @@ -0,0 +1,84 @@ +/* Freezer declarations */ + +#ifdef CONFIG_PM +/* + * Check if a process has been frozen + */ +static inline int frozen(struct task_struct *p) +{ + return p->flags & PF_FROZEN; +} + +/* + * Check if there is a request to freeze a process + */ +static inline int freezing(struct task_struct *p) +{ + return p->flags & PF_FREEZE; +} + +/* + * Request that a process be frozen + * FIXME: SMP problem. We may not modify other process' flags! + */ +static inline void freeze(struct task_struct *p) +{ + p->flags |= PF_FREEZE; +} + +/* + * Sometimes we may need to cancel the previous 'freeze' request + */ +static inline void do_not_freeze(struct task_struct *p) +{ + p->flags &= ~PF_FREEZE; +} + +/* + * Wake up a frozen process + */ +static inline int thaw_process(struct task_struct *p) +{ + if (frozen(p)) { + p->flags &= ~PF_FROZEN; + wake_up_process(p); + return 1; + } + return 0; +} + +/* + * freezing is complete, mark process as frozen + */ +static inline void frozen_process(struct task_struct *p) +{ + p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN; +} + +extern void refrigerator(void); +extern int freeze_processes(void); +extern void thaw_processes(void); + +static inline int try_to_freeze(void) +{ + if (freezing(current)) { + refrigerator(); + return 1; + } else + return 0; +} +#else +static inline int frozen(struct task_struct *p) { return 0; } +static inline int freezing(struct task_struct *p) { return 0; } +static inline void freeze(struct task_struct *p) { BUG(); } +static inline int thaw_process(struct task_struct *p) { return 1; } +static inline void frozen_process(struct task_struct *p) { BUG(); } + +static inline void refrigerator(void) {} +static inline int freeze_processes(void) { BUG(); return 0; } +static inline void thaw_processes(void) {} + +static inline int try_to_freeze(void) { return 0; } + + +#endif -- cgit v1.2.3 From ff39593ad0ff7a79a3717edac6634407aa8200c2 Mon Sep 17 00:00:00 2001 From: Nigel Cunningham Date: Wed, 6 Dec 2006 20:34:28 -0800 Subject: [PATCH] swsusp: thaw userspace and kernel space separately Modify process thawing so that we can thaw kernel space without thawing userspace, and thaw kernelspace first. This will be useful in later patches, where I intend to get swsusp thawing kernel threads only before seeking to free memory. Signed-off-by: Nigel Cunningham Cc: Pavel Machek Cc: "Rafael J. Wysocki" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/freezer.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'include/linux/freezer.h') diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 266373f7444..294ebea859c 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -1,5 +1,8 @@ /* Freezer declarations */ +#define FREEZER_KERNEL_THREADS 0 +#define FREEZER_ALL_THREADS 1 + #ifdef CONFIG_PM /* * Check if a process has been frozen @@ -57,7 +60,8 @@ static inline void frozen_process(struct task_struct *p) extern void refrigerator(void); extern int freeze_processes(void); -extern void thaw_processes(void); +#define thaw_processes() do { thaw_some_processes(FREEZER_ALL_THREADS); } while(0) +#define thaw_kernel_threads() do { thaw_some_processes(FREEZER_KERNEL_THREADS); } while(0) static inline int try_to_freeze(void) { @@ -67,6 +71,9 @@ static inline int try_to_freeze(void) } else return 0; } + +extern void thaw_some_processes(int all); + #else static inline int frozen(struct task_struct *p) { return 0; } static inline int freezing(struct task_struct *p) { return 0; } -- cgit v1.2.3 From a9b6f562f14dc28fb4b2415f0f275cede0abe9b5 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 6 Dec 2006 20:34:37 -0800 Subject: [PATCH] swsusp: Untangle thaw_processes Move the loop from thaw_processes() to a separate function and call it independently for kernel threads and user space processes so that the order of thawing tasks is clearly visible. Drop thaw_kernel_threads() which is never used. Signed-off-by: Rafael J. Wysocki Cc: Pavel Machek Cc: Nigel Cunningham Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/freezer.h | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'include/linux/freezer.h') diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 294ebea859c..6e05e3e7ce3 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -1,8 +1,5 @@ /* Freezer declarations */ -#define FREEZER_KERNEL_THREADS 0 -#define FREEZER_ALL_THREADS 1 - #ifdef CONFIG_PM /* * Check if a process has been frozen @@ -60,8 +57,7 @@ static inline void frozen_process(struct task_struct *p) extern void refrigerator(void); extern int freeze_processes(void); -#define thaw_processes() do { thaw_some_processes(FREEZER_ALL_THREADS); } while(0) -#define thaw_kernel_threads() do { thaw_some_processes(FREEZER_KERNEL_THREADS); } while(0) +extern void thaw_processes(void); static inline int try_to_freeze(void) { -- cgit v1.2.3 From 5c543eff6cc658f46241f1ccb77436d65abbf445 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Sun, 10 Dec 2006 02:18:58 -0800 Subject: [PATCH] freezer.h uses task_struct fields freezer.h uses task_struct fields so it should include sched.h. CC [M] fs/jfs/jfs_txnmgr.o In file included from fs/jfs/jfs_txnmgr.c:49: include/linux/freezer.h: In function 'frozen': include/linux/freezer.h:9: error: dereferencing pointer to incomplete type include/linux/freezer.h:9: error: 'PF_FROZEN' undeclared (first use in this function) include/linux/freezer.h:9: error: (Each undeclared identifier is reported only once include/linux/freezer.h:9: error: for each function it appears in.) include/linux/freezer.h: In function 'freezing': include/linux/freezer.h:17: error: dereferencing pointer to incomplete type include/linux/freezer.h:17: error: 'PF_FREEZE' undeclared (first use in this function) include/linux/freezer.h: In function 'freeze': include/linux/freezer.h:26: error: dereferencing pointer to incomplete type include/linux/freezer.h:26: error: 'PF_FREEZE' undeclared (first use in this function) include/linux/freezer.h: In function 'do_not_freeze': include/linux/freezer.h:34: error: dereferencing pointer to incomplete type include/linux/freezer.h:34: error: 'PF_FREEZE' undeclared (first use in this function) include/linux/freezer.h: In function 'thaw_process': include/linux/freezer.h:43: error: dereferencing pointer to incomplete type include/linux/freezer.h:43: error: 'PF_FROZEN' undeclared (first use in this function) include/linux/freezer.h:44: warning: implicit declaration of function 'wake_up_process' include/linux/freezer.h: In function 'frozen_process': include/linux/freezer.h:55: error: dereferencing pointer to incomplete type include/linux/freezer.h:55: error: dereferencing pointer to incomplete type include/linux/freezer.h:55: error: 'PF_FREEZE' undeclared (first use in this function) include/linux/freezer.h:55: error: 'PF_FROZEN' undeclared (first use in this function) fs/jfs/jfs_txnmgr.c: In function 'freezing': include/linux/freezer.h:18: warning: control reaches end of non-void function make[2]: *** [fs/jfs/jfs_txnmgr.o] Error 1 Signed-off-by: Randy Dunlap Acked-by: Dave Kleikamp Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/freezer.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/freezer.h') diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 6e05e3e7ce3..39306309613 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -1,5 +1,7 @@ /* Freezer declarations */ +#include + #ifdef CONFIG_PM /* * Check if a process has been frozen -- cgit v1.2.3 From 8a102eed9c4e1d21bad07a8fd97bd4fbf125d966 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 13 Dec 2006 00:34:30 -0800 Subject: [PATCH] PM: Fix SMP races in the freezer Currently, to tell a task that it should go to the refrigerator, we set the PF_FREEZE flag for it and send a fake signal to it. Unfortunately there are two SMP-related problems with this approach. First, a task running on another CPU may be updating its flags while the freezer attempts to set PF_FREEZE for it and this may leave the task's flags in an inconsistent state. Second, there is a potential race between freeze_process() and refrigerator() in which freeze_process() running on one CPU is reading a task's PF_FREEZE flag while refrigerator() running on another CPU has just set PF_FROZEN for the same task and attempts to reset PF_FREEZE for it. If the refrigerator wins the race, freeze_process() will state that PF_FREEZE hasn't been set for the task and will set it unnecessarily, so the task will go to the refrigerator once again after it's been thawed. To solve first of these problems we need to stop using PF_FREEZE to tell tasks that they should go to the refrigerator. Instead, we can introduce a special TIF_*** flag and use it for this purpose, since it is allowed to change the other tasks' TIF_*** flags and there are special calls for it. To avoid the freeze_process()-refrigerator() race we can make freeze_process() to always check the task's PF_FROZEN flag after it's read its "freeze" flag. We should also make sure that refrigerator() will always reset the task's "freeze" flag after it's set PF_FROZEN for it. Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek Cc: Russell King Cc: David Howells Cc: Andi Kleen Cc: "Luck, Tony" Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Paul Mundt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/freezer.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'include/linux/freezer.h') diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 39306309613..5e75e26d478 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -16,16 +16,15 @@ static inline int frozen(struct task_struct *p) */ static inline int freezing(struct task_struct *p) { - return p->flags & PF_FREEZE; + return test_tsk_thread_flag(p, TIF_FREEZE); } /* * Request that a process be frozen - * FIXME: SMP problem. We may not modify other process' flags! */ static inline void freeze(struct task_struct *p) { - p->flags |= PF_FREEZE; + set_tsk_thread_flag(p, TIF_FREEZE); } /* @@ -33,7 +32,7 @@ static inline void freeze(struct task_struct *p) */ static inline void do_not_freeze(struct task_struct *p) { - p->flags &= ~PF_FREEZE; + clear_tsk_thread_flag(p, TIF_FREEZE); } /* @@ -54,7 +53,9 @@ static inline int thaw_process(struct task_struct *p) */ static inline void frozen_process(struct task_struct *p) { - p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN; + p->flags |= PF_FROZEN; + wmb(); + clear_tsk_thread_flag(p, TIF_FREEZE); } extern void refrigerator(void); -- cgit v1.2.3