tick/nohz: Prevent bogus softirq pending warning
authorThomas Gleixner <tglx@linutronix.de>
Thu, 30 Aug 2018 15:05:19 +0000 (17:05 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 29 Sep 2018 10:06:07 +0000 (03:06 -0700)
commited5e9462f6617a85945353abe5c4b94a81ee01a1
tree7f0d7b7fe1fd545f92190dc18c96f63ff9c238f7
parent3a411a04be4e57de1774f680d3d6d0d48cc16c10
tick/nohz: Prevent bogus softirq pending warning

Commit 0a0e0829f990 ("nohz: Fix missing tick reprogram when interrupting an
inline softirq") got backported to stable trees and now causes the NOHZ
softirq pending warning to trigger. It's not an upstream issue as the NOHZ
update logic has been changed there.

The problem is when a softirq disabled section gets interrupted and on
return from interrupt the tick/nohz state is evaluated, which then can
observe pending soft interrupts. These soft interrupts are legitimately
pending because they cannot be processed as long as soft interrupts are
disabled and the interrupted code will correctly process them when soft
interrupts are reenabled.

Add a check for softirqs disabled to the pending check to prevent the
warning.

Reported-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reported-by: John Crispin <john@phrozen.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>
Tested-by: John Crispin <john@phrozen.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: 2d898915ccf4838c ("nohz: Fix missing tick reprogram when interrupting an inline softirq")
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
kernel/time/tick-sched.c