sched/fair: remove printk while schedule is in progress
It will cause deadlock and while(1) if call printk while schedule is in
progress. The block state like as below:
cpu0(hold the console sem):
printk->console_unlock->up_sem->spin_lock(&sem->lock)->wake_up_process(cpu1)
->try_to_wake_up(cpu1)->while(p->on_cpu).
cpu1(request console sem):
console_lock->down_sem->schedule->idle_banlance->update_cpu_capacity->
printk->console_trylock->spin_lock(&sem->lock).
p->on_cpu will be 1 forever, because the task is still running on cpu1,
so cpu0 is blocked in while(p->on_cpu), but cpu1 could not get
spin_lock(&sem->lock), it is blocked too, it means the task will running
on cpu1 forever.
Change-Id: I61f5633b5e8dfa4fb6bac801dc1732a5494a0a88
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Git-commit: df232437710122fcb4e4a0484a1eded5aec29a6a
Git-repo: https://android.googlesource.com/kernel/msm
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
1 file changed