workqueue: use irqsafe timer for delayed_work

Up to now, for delayed_works, try_to_grab_pending() couldn't be used
from IRQ handlers because IRQs may happen while
delayed_work_timer_fn() is in progress leading to indefinite -EAGAIN.

This patch makes delayed_work use the new TIMER_IRQSAFE flag for
delayed_work->timer.  This makes try_to_grab_pending() and thus
mod_delayed_work_on() safe to call from IRQ handlers.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index e84ebb69607..d86b320319e 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -136,7 +136,8 @@ struct execute_work {
 #define __DELAYED_WORK_INITIALIZER(n, f, tflags) {                      \
         .work = __WORK_INITIALIZER((n).work, (f)),                      \
         .timer = __TIMER_INITIALIZER(delayed_work_timer_fn,             \
-                        0, (unsigned long)&(n), (tflags)),              \
+                                     0, (unsigned long)&(n),            \
+                                     (tflags) | TIMER_IRQSAFE),         \
         }
 
 #define DECLARE_WORK(n, f)                                              \
@@ -214,7 +215,8 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
         do {                                                            \
                 INIT_WORK(&(_work)->work, (_func));                     \
                 __setup_timer(&(_work)->timer, delayed_work_timer_fn,   \
-                              (unsigned long)(_work), (_tflags));       \
+                              (unsigned long)(_work),                   \
+                              (_tflags) | TIMER_IRQSAFE);               \
         } while (0)
 
 #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)              \
@@ -223,7 +225,7 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
                 __setup_timer_on_stack(&(_work)->timer,                 \
                                        delayed_work_timer_fn,           \
                                        (unsigned long)(_work),          \
-                                       (_tflags));                      \
+                                       (_tflags) | TIMER_IRQSAFE);      \
         } while (0)
 
 #define INIT_DELAYED_WORK(_work, _func)                                 \