On 15.07.2015 15:16, Eric Dumazet wrote:
On Wed, 2015-07-15 at 12:52 +0300, Konstantin Khlebnikov wrote:
These functions check should_resched() before unlocking spinlock/bh-enable:
preempt_count always non-zero => should_resched() always returns false.
cond_resched_lock() worked iff spin_needbreak is set.
Interesting, this definitely used to work (linux-3.11)
Any idea of which commit broke things ?
Searching... done
This one: bdb43806589096ac4272fe1307e789846ac08d7c in v3.13
before
-static inline int should_resched(void)
-{
- return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
-}
after
+static __always_inline bool should_resched(void)
+{
+ return unlikely(!*preempt_count_ptr());
+}
So,
Fixes: bdb438065890 ("sched: Extract the basic add/sub preempt_count
modifiers")
--
Konstantin
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