On 04/18/2016 02:31 AM, Davidlohr Bueso wrote:
... remove the redundant second iteration, this is most likely a copy/past buglet.Signed-off-by: Davidlohr Bueso<dbu...@suse.de> --- kernel/locking/qspinlock_stat.h | 2 -- 1 file changed, 2 deletions(-) diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h index d734b7502001..72722334237a 100644 --- a/kernel/locking/qspinlock_stat.h +++ b/kernel/locking/qspinlock_stat.h @@ -191,8 +191,6 @@ static ssize_t qstat_write(struct file *file, const char __user *user_buf, for (i = 0 ; i< qstat_num; i++) WRITE_ONCE(ptr[i], 0); - for (i = 0 ; i< qstat_num; i++) - WRITE_ONCE(ptr[i], 0); } return count; }
The double write is done on purpose. As the statistics count update isn't atomic, there is a very small chance (p) that clearing the count may happen in the middle of read-modify-write bus transaction. Doing a double write will reduce the chance further to p^2. This isn't failsafe, but I think is good enough.
However, I don't mind eliminate the double write either as we can always view the statistics count after a reset to make sure that they are properly cleared.
Cheers, Longman
