user/sven/linux.git/include/linux/freezer.h, branch v3.4.15

PM / Hibernate: Fix s2disk regression related to freezing workqueues

2012-01-29T19:35:52Z

Commit 2aede851ddf08666f68ffc17be446420e9d2a056 PM / Hibernate: Freeze kernel threads after preallocating memory introduced a mechanism by which kernel threads were frozen after the preallocation of hibernate image memory to avoid problems with frozen kernel threads not responding to memory freeing requests. However, it overlooked the s2disk code path in which the SNAPSHOT_CREATE_IMAGE ioctl was run directly after SNAPSHOT_FREE, which caused freeze_workqueues_begin() to BUG(), because it saw that worqueues had been already frozen. Although in principle this issue might be addressed by removing the relevant BUG_ON() from freeze_workqueues_begin(), that would reintroduce the very problem that commit 2aede851ddf08666f68ffc17be4 attempted to avoid into that particular code path. For this reason, to fix the issue at hand, introduce thaw_kernel_threads() and make the SNAPSHOT_FREE ioctl execute it. Special thanks to Srivatsa S. Bhat for detailed analysis of the problem. Reported-and-tested-by: Jiri Slaby Signed-off-by: Rafael J. Wysocki Acked-by: Srivatsa S. Bhat Cc: stable@kernel.org

PM / Freezer: fix return value of freezable_schedule_timeout_killable()

2011-12-27T00:06:33Z

...it should return the return code from schedule_timeout_killable(), not the one from freezer_count(). All of the current callers ignore the return code so the bug is harmless but it's worth fixing. Signed-off-by: Jeff Layton Signed-off-by: Rafael J. Wysocki

PM / Freezer: Remove the "userspace only" constraint from freezer[_do_not]_count()

2011-12-08T22:21:01Z

At present, the functions freezer_count() and freezer_do_not_count() impose the restriction that they are effective only for userspace processes. However, now, these functions have found more utility than originally intended by the commit which introduced it: ba96a0c8 (freezer: fix vfork problem). And moreover, even the vfork issue actually does not need the above restriction in these functions. So, modify these functions to make them work even for kernel threads, so that they can be used at other places in the kernel, where the userspace restriction doesn't apply. Suggested-by: Oleg Nesterov Suggested-by: Tejun Heo Acked-by: Tejun Heo Reviewed-by: Oleg Nesterov Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki

Freezer / sunrpc / NFS: don't allow TASK_KILLABLE sleeps to block the freezer

2011-12-06T21:12:27Z

Allow the freezer to skip wait_on_bit_killable sleeps in the sunrpc layer. This should allow suspend and hibernate events to proceed, even when there are RPC's pending on the wire. Also, wrap the TASK_KILLABLE sleeps in NFS layer in freezer_do_not_count and freezer_count calls. This allows the freezer to skip tasks that are sleeping while looping on EJUKEBOX or NFS4ERR_DELAY sorts of errors. Signed-off-by: Jeff Layton Signed-off-by: Rafael J. Wysocki

Freezer: fix more fallout from the thaw_process rename

2011-11-24T23:44:55Z

Commit 944e192db53c "freezer: rename thaw_process() to __thaw_task() and simplify the implementation" did not create a !CONFIG_FREEZER version of __thaw_task(). Signed-off-by: Stephen Rothwell Signed-off-by: Rafael J. Wysocki

freezer: fix wait_event_freezable/__thaw_task races

2011-11-23T17:28:17Z

wait_event_freezable() and friends stop the waiting if try_to_freeze() fails. This is not right, we can race with __thaw_task() and in this case - wait_event_freezable() returns the wrong ERESTARTSYS - wait_event_freezable_timeout() can return the positive value while condition == F Change the code to always check __retval/condition before return. Note: with or without this patch the timeout logic looks strange, probably we should recalc timeout if try_to_freeze() returns T. Signed-off-by: Oleg Nesterov Acked-by: Tejun Heo

freezer: kill unused set_freezable_with_signal()

2011-11-23T17:28:17Z

There's no in-kernel user of set_freezable_with_signal() left. Mixing TIF_SIGPENDING with kernel threads can lead to nasty corner cases as kernel threads never travel signal delivery path on their own. e.g. the current implementation is buggy in the cancelation path of __thaw_task(). It calls recalc_sigpending_and_wake() in an attempt to clear TIF_SIGPENDING but the function never clears it regardless of sigpending state. This means that signallable freezable kthreads may continue executing with !freezing() && stuck TIF_SIGPENDING, which can be troublesome. This patch removes set_freezable_with_signal() along with PF_FREEZER_NOSIG and recalc_sigpending*() calls in freezer. User tasks get TIF_SIGPENDING, kernel tasks get woken up and the spurious sigpending is dealt with in the usual signal delivery path. Signed-off-by: Tejun Heo Acked-by: Oleg Nesterov

freezer: remove unused @sig_only from freeze_task()

2011-11-21T20:32:26Z

After "freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE", freezing() returns authoritative answer on whether the current task should freeze or not and freeze_task() doesn't need or use @sig_only. Remove it. While at it, rewrite function comment for freeze_task() and rename @sig_only to @user_only in try_to_freeze_tasks(). This patch doesn't cause any functional change. Signed-off-by: Tejun Heo Acked-by: Oleg Nesterov

freezer: fix set_freezable[_with_signal]() race

2011-11-21T20:32:25Z

A kthread doing set_freezable*() may race with on-going PM freeze and the freezer might think all tasks are frozen while the new freezable kthread is merrily proceeding to execute code paths which aren't supposed to be executing during PM freeze. Reimplement set_freezable[_with_signal]() using __set_freezable() such that freezable PF flags are modified under freezer_lock and try_to_freeze() is called afterwards. This eliminates race condition against freezing. Note: Separated out from larger patch to resolve fix order dependency Oleg pointed out. Signed-off-by: Tejun Heo Cc: Oleg Nesterov

freezer: remove should_send_signal() and update frozen()

2011-11-21T20:32:25Z

should_send_signal() is only used in freezer.c. Exporting them only increases chance of abuse. Open code the two users and remove it. Update frozen() to return bool. Signed-off-by: Tejun Heo