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2006-12-13[PATCH] PM: Fix SMP races in the freezerRafael J. Wysocki
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 <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Russell King <rmk@arm.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Cc: Andi Kleen <ak@muc.de> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-10[PATCH] freezer.h uses task_struct fieldsRandy Dunlap
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 <randy.dunlap@oracle.com> Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] swsusp: Untangle thaw_processesRafael J. Wysocki
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 <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Cc: Nigel Cunningham <nigel@suspend2.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] swsusp: thaw userspace and kernel space separatelyNigel Cunningham
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 <nigel@suspend2.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] Add include/linux/freezer.h and move definitions from sched.hNigel Cunningham
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 <nigel@suspend2.net> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>