Messages in this thread Patch in this message | | | Date | Tue, 8 Sep 2015 19:14:52 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 3/3] Revert "task_work: remove fifo ordering guarantee" |
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This reverts commit c82199061009d1561e31e17fca5e47a87cb7ff4c.
Now that fput() can't abuse ->task_works list, we can restore the FIFO ordering. Yes, currently there are no in-kernel users which need this, but I think task_work_add() will have more users and FIFO makes more sense if (unlike fput/mntput) the callbacks change the task's state.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- kernel/task_work.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/task_work.c b/kernel/task_work.c index 53fa971..8727032 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -18,8 +18,6 @@ static struct callback_head work_exited; /* all we need is ->next == NULL */ * This is like the signal handler which runs in kernel mode, but it doesn't * try to wake up the @task. * - * Note: there is no ordering guarantee on works queued here. - * * RETURNS: * 0 if succeeds or -ESRCH. */ @@ -110,6 +108,16 @@ void task_work_run(void) raw_spin_unlock_wait(&task->pi_lock); smp_mb(); + /* Reverse the list to run the works in fifo order */ + head = NULL; + do { + next = work->next; + work->next = head; + head = work; + work = next; + } while (work); + + work = head; do { next = work->next; work->func(work); -- 2.4.3
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