[PATCH RT] x86/preempt-lazy: fixup should_resched()
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2016-09-14 17:22:33
Also in:
lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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 <bigeasy@linutronix.de> --- 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 190af4271b5c..58fd4ff3f53a 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
--
2.9.3