Commit 4ca360f3 authored by Kautuk Consul's avatar Kautuk Consul Committed by Michael Ellerman
Browse files

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: default avatarKautuk Consul <>
[mpe: Confirmed other architectures do similar]
Signed-off-by: default avatarMichael Ellerman <>
parent 06755a87
......@@ -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];
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