Commit 4ca360f3 authored Apr 19, 2016 by Kautuk Consul Committed by Michael Ellerman Oct 06, 2017

powerpc: get_wchan(): solve possible race scenario due to parallel wakeup



Add a check for p->state == TASK_RUNNING so that any wake-ups on
task_struct p in the interim lead to 0 being returned by get_wchan().

Signed-off-by: Kautuk Consul <kautuk.consul.1980@gmail.com>
[mpe: Confirmed other architectures do similar]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent 06755a87

arch/powerpc/kernel/process.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1898,7 +1898,8 @@ unsigned long get_wchan(struct task_struct *p)

		do {
		sp = (unsigned long )sp;
		if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
		if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) \|\|
		p->state == TASK_RUNNING)
		return 0;
		if (count > 0) {
		ip = ((unsigned long *)sp)[STACK_FRAME_LR_SAVE];