The patch titled
migrate_timers: add comment, use spinlock_irq()
has been removed from the -mm tree. Its filename was
migrate_timers-add-comment-use-spinlock_irq.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: migrate_timers: add comment, use spinlock_irq()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Add the comment to explain why the double lock in migrate_timers()
can't deadlock.
Change the code to use spinlock_irq() instead of local_irq_disable()
+ spin_lock().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Steven Rostedt <srostedt@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/hrtimer.c | 11 ++++++-----
kernel/timer.c | 11 ++++++-----
2 files changed, 12 insertions(+), 10 deletions(-)
diff -puN kernel/hrtimer.c~migrate_timers-add-comment-use-spinlock_irq kernel/hrtimer.c
--- a/kernel/hrtimer.c~migrate_timers-add-comment-use-spinlock_irq
+++ a/kernel/hrtimer.c
@@ -1620,9 +1620,11 @@ static void migrate_hrtimers(int cpu)
new_base = &get_cpu_var(hrtimer_bases);
tick_cancel_sched_timer(cpu);
-
- local_irq_disable();
- spin_lock(&new_base->lock);
+ /*
+ * The caller is globally serialized and nobody else
+ * takes two locks at once, deadlock is not possible.
+ */
+ spin_lock_irq(&new_base->lock);
spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
@@ -1631,8 +1633,7 @@ static void migrate_hrtimers(int cpu)
}
spin_unlock(&old_base->lock);
- spin_unlock(&new_base->lock);
- local_irq_enable();
+ spin_unlock_irq(&new_base->lock);
put_cpu_var(hrtimer_bases);
}
#endif /* CONFIG_HOTPLUG_CPU */
diff -puN kernel/timer.c~migrate_timers-add-comment-use-spinlock_irq kernel/timer.c
--- a/kernel/timer.c~migrate_timers-add-comment-use-spinlock_irq
+++ a/kernel/timer.c
@@ -1436,9 +1436,11 @@ static void __cpuinit migrate_timers(int
BUG_ON(cpu_online(cpu));
old_base = per_cpu(tvec_bases, cpu);
new_base = get_cpu_var(tvec_bases);
-
- local_irq_disable();
- spin_lock(&new_base->lock);
+ /*
+ * The caller is globally serialized and nobody else
+ * takes two locks at once, deadlock is not possible.
+ */
+ spin_lock_irq(&new_base->lock);
spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
BUG_ON(old_base->running_timer);
@@ -1453,8 +1455,7 @@ static void __cpuinit migrate_timers(int
}
spin_unlock(&old_base->lock);
- spin_unlock(&new_base->lock);
- local_irq_enable();
+ spin_unlock_irq(&new_base->lock);
put_cpu_var(tvec_bases);
}
#endif /* CONFIG_HOTPLUG_CPU */
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
linux-next.patch
posix-timers-dont-switch-to-group_leader-if-it_process-dies.patch
posix-timers-always-do-get_task_structtimer-it_process.patch
posix-timers-sys_timer_create-remove-the-buggy-pf_exiting-check.patch
posix-timers-sys_timer_create-simplify-and-s-tasklist-rcu.patch
posix-timers-move-the-initialization-of-timer-sigq-from-send-to-create-path.patch
posix-timers-sys_timer_create-cleanup-the-error-handling.patch
posix-timers-kill-it_sigev_signo-and-it_sigev_value.patch
posix-timers-lock_timer-kill-the-bogus-it_id-check.patch
posix-timers-lock_timer-make-it-readable.patch
posix-timers-use-struct-pid-instead-of-struct-task_struct.patch
posix-timers-check-it_signal-instead-of-it_pid-to-validate-the-timer.patch
posix-timers-simplify-de_thread-exit_itimers-path.patch
make-ptrace_untrace-static.patch
coredump-format_corename-dont-append-%pid-if-multi-threaded.patch
kthread_bind-use-wait_task_inactivetask_uninterruptible.patch
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