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[PATCH RT 06/11] arm: lazy preempt: correct resched condition

From Steven Rostedt <rostedt@goodmis.org>
Newsgroups linux.kernel
Subject [PATCH RT 06/11] arm: lazy preempt: correct resched condition
Date 2016-07-12 19:00 +0200
Message-ID <rU9cn-7AG-49@gated-at.bofh.it> (permalink)
References <rU9cl-7AG-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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3.12.61-rt82-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

If we get out of preempt_schedule_irq() then we check for NEED_RESCHED
and call the former function again if set because the preemption counter
has be zero at this point.
However the counter for lazy-preempt might not be zero therefore we have
to check the counter before looking at the need_resched_lazy flag.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/arm/kernel/entry-armv.S | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 8c5e809c1f07..96eb4d26a5c1 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -234,7 +234,11 @@ svc_preempt:
 	bne	1b
 	tst	r0, #_TIF_NEED_RESCHED_LAZY
 	moveq	pc, r8				@ go again
-	b	1b
+	ldr	r0, [tsk, #TI_PREEMPT_LAZY]	@ get preempt lazy count
+	teq	r0, #0				@ if preempt lazy count != 0
+	beq	1b
+	mov	pc, r8				@ go again
+
 #endif
 
 __und_fault:
-- 
2.8.1

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Thread

[PATCH RT 00/11] Linux 3.12.61-rt82-rc1 Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 10/11] x86: Fix an RT MCE crash Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 11/11] Linux 3.12.61-rt82-rc1 Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 07/11] locallock: add local_lock_on() Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 08/11] mm: perform lru_add_drain_all() remotely Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 06/11] arm: lazy preempt: correct resched condition Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 09/11] trace: correct off by one while recording the trace-event Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 01/11] kvm, rt: change async pagefault code locking for PREEMPT_RT Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 03/11] list_bl: fixup bogus lockdep warning Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  [PATCH RT 02/11] net: dev: always take qdiscs busylock in __dev_xmit_skb() Steven Rostedt <rostedt@goodmis.org> - 2016-07-12 19:00 +0200
  Linux 3.12.61-rt82-rc2 Steven Rostedt <rostedt@goodmis.org> - 2016-07-13 01:30 +0200

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