[PATCH RT 08/10] x86/preempt-lazy: fixup should_resched()
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2016-09-22 23:18:40
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Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
3.18.42-rt45-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior <bigeasy@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 <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- arch/x86/include/asm/preempt.h | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 060d1b4e475d..6806369bddf5 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h@@ -95,6 +95,8 @@ 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;
@@ -107,8 +109,18 @@ static __always_inline bool __preempt_count_dec_and_test(void) static __always_inline bool should_resched(void) { #ifdef CONFIG_PREEMPT_LAZY - return unlikely(!raw_cpu_read_4(__preempt_count) || \ - test_thread_flag(TIF_NEED_RESCHED_LAZY)); + u32 tmp; + + if (!raw_cpu_read_4(__preempt_count)) + 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)); #endif
--
2.8.1