4.4.21-rt31-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bige...@linutronix.de>
should_resched() returns true if NEED_RESCHED is set and the
preempt_count is 0 _or_ if NEED_RESCHED_LAZY is set ignoring the preempt
counter. Ignoring the preemp counter is wrong. This patch adds this into
account.
While at it, __preempt_count_dec_and_test() ignores preempt_lazy_count
while checking TIF_NEED_RESCHED_LAZY so we this check, too.
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Signed-off-by: Steven Rostedt <rost...@goodmis.org>
---
arch/x86/include/asm/preempt.h | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 5dbd2d0f91e0..6f432adc55cd 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -89,6 +89,8 @@ static __always_inline bool __preempt_count_dec_and_test(void)
if (____preempt_count_dec_and_test())
return true;
#ifdef CONFIG_PREEMPT_LAZY
+ if (current_thread_info()->preempt_lazy_count)
+ return false;
return test_thread_flag(TIF_NEED_RESCHED_LAZY);
#else
return false;
@@ -101,8 +103,19 @@ static __always_inline bool
__preempt_count_dec_and_test(void)
static __always_inline bool should_resched(int preempt_offset)
{
#ifdef CONFIG_PREEMPT_LAZY
- return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset ||
- test_thread_flag(TIF_NEED_RESCHED_LAZY));
+ u32 tmp;
+
+ tmp = raw_cpu_read_4(__preempt_count);
+ if (tmp == preempt_offset)
+ return true;
+
+ /* preempt count == 0 ? */
+ tmp &= ~PREEMPT_NEED_RESCHED;
+ if (tmp)
+ return false;
+ if (current_thread_info()->preempt_lazy_count)
+ return false;
+ return test_thread_flag(TIF_NEED_RESCHED_LAZY);
#else
return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
#endif
--
2.8.1
