rt-patches/0346-arm-lazy-preempt-correct-resched-condition.patch

   1 From 6de82414e10f5a7045655094f38e99b6f9dee7d2 Mon Sep 17 00:00:00 2001
   2 From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
   3 Date: Tue, 24 May 2016 12:56:38 +0200
   4 Subject: [PATCH 346/365] arm: lazy preempt: correct resched condition
   5
   6 If we get out of preempt_schedule_irq() then we check for NEED_RESCHED
   7 and call the former function again if set because the preemption counter
   8 has be zero at this point.
   9 However the counter for lazy-preempt might not be zero therefore we have
  10 to check the counter before looking at the need_resched_lazy flag.
  11
  12 Cc: stable-rt@vger.kernel.org
  13 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  14 ---
  15  arch/arm/kernel/entry-armv.S | 6 +++++-
  16  1 file changed, 5 insertions(+), 1 deletion(-)
  17
  18 diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
  19 index d66b1ae..d044cea 100644
  20 --- a/arch/arm/kernel/entry-armv.S
  21 +++ b/arch/arm/kernel/entry-armv.S
  22 @@ -244,7 +244,11 @@ svc_preempt:
  23         bne     1b
  24         tst     r0, #_TIF_NEED_RESCHED_LAZY
  25         reteq   r8                              @ go again
  26 -       b       1b
  27 +       ldr     r0, [tsk, #TI_PREEMPT_LAZY]     @ get preempt lazy count
  28 +       teq     r0, #0                          @ if preempt lazy count != 0
  29 +       beq     1b
  30 +       ret     r8                              @ go again
  31 +
  32  #endif
  33
  34  __und_fault:
  35 --
  36 2.7.4
  37