From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>
Subject: [PATCH RT 08/10] x86/preempt-lazy: fixup should_resched()
Date: Thu, 22 Sep 2016 17:57:55 -0400 [thread overview]
Message-ID: <20160922215834.781622917@goodmis.org> (raw)
In-Reply-To: 20160922215747.696761304@goodmis.org
[-- Attachment #1: 0008-x86-preempt-lazy-fixup-should_resched.patch --]
[-- Type: text/plain, Size: 1932 bytes --]
4.1.33-rt38-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 | 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 c08949b0314d..eff1b8609f77 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -92,6 +92,8 @@ 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;
@@ -104,8 +106,19 @@ 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
next prev parent reply other threads:[~2016-09-22 21:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-22 21:57 [PATCH RT 00/10] Linux 4.1.33-rt38-rc1 Steven Rostedt
2016-09-22 21:57 ` [PATCH RT 01/10] timers: wakeup all timer waiters Steven Rostedt
2016-09-22 21:57 ` [PATCH RT 02/10] timers: wakeup all timer waiters without holding the base lock Steven Rostedt
2016-09-22 21:57 ` [PATCH RT 03/10] sched: lazy_preempt: avoid a warning in the !RT case Steven Rostedt
2016-09-22 21:57 ` [PATCH RT 04/10] scsi/fcoe: Fix get_cpu()/put_cpu_light() imbalance in fcoe_recv_frame() Steven Rostedt
2016-09-22 21:57 ` [PATCH RT 06/10] net: add a lock around icmp_sk() Steven Rostedt
2016-09-22 21:57 ` [PATCH RT 07/10] fs/dcache: resched/chill only if we make no progress Steven Rostedt
2016-09-22 21:57 ` Steven Rostedt [this message]
2016-09-22 21:57 ` [PATCH RT 09/10] fs/dcache: incremental fixup of the retry routine Steven Rostedt
2016-09-22 21:57 ` [PATCH RT 10/10] Linux 4.1.33-rt38-rc1 Steven Rostedt
[not found] ` <20160922215834.076247330@goodmis.org>
2016-09-22 22:04 ` [PATCH RT 05/10] net: add back the missing serialization in ip_send_unicast_reply() Steven Rostedt
-- strict thread matches above, loose matches on Subject: below --
2016-09-23 2:49 [PATCH RT 00/10] Linux 3.14.79-rt85-rc1 Steven Rostedt
2016-09-23 2:49 ` [PATCH RT 08/10] x86/preempt-lazy: fixup should_resched() Steven Rostedt
2016-09-22 23:17 [PATCH RT 00/10] Linux 3.18.42-rt45-rc1 Steven Rostedt
2016-09-22 23:17 ` [PATCH RT 08/10] x86/preempt-lazy: fixup should_resched() Steven Rostedt
2016-09-22 21:47 [PATCH RT 00/10] Linux 4.4.21-rt31-rc1 Steven Rostedt
2016-09-22 21:48 ` [PATCH RT 08/10] x86/preempt-lazy: fixup should_resched() Steven Rostedt
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