userfaultfd: revert "userfaultfd: waitqueue: add nr wake parameter to __wake_up_locked_key"

This reverts commit 51360155ec and adapts
fs/userfaultfd.c to use the old version of that function.

It didn't look robust to call __wake_up_common with "nr == 1" when we
absolutely require wakeall semantics, but we've full control of what we
insert in the two waitqueue heads of the blocked userfaults.  No
exclusive waitqueue risks to be inserted into those two waitqueue heads
so we can as well stick to "nr == 1" of the old code and we can rely
purely on the fact no waitqueue inserted in one of the two waitqueue
heads we must enforce as wakeall, has wait->flags WQ_FLAG_EXCLUSIVE set.

Signed-off-by: Andrea Arcangeli <[email protected]>
Cc: Dr. David Alan Gilbert <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Thierry Reding <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Andrea Arcangeli 2015-09-22 14:58:49 -07:00 • committed by Linus Torvalds
commit ac5be6b47e
4 changed files with 10 additions and 12 deletions

View file

@ -467,8 +467,8 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
* the fault_*wqh.
*/
spin_lock(&ctx->fault_pending_wqh.lock);
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, 0, &range);
__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, 0, &range);
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range);
__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, &range);
spin_unlock(&ctx->fault_pending_wqh.lock);
wake_up_poll(&ctx->fd_wqh, POLLHUP);
@ -650,10 +650,10 @@ static void __wake_userfault(struct userfaultfd_ctx *ctx,
spin_lock(&ctx->fault_pending_wqh.lock);
/* wake all in the range and autoremove */
if (waitqueue_active(&ctx->fault_pending_wqh))
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, 0,
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL,
range);
if (waitqueue_active(&ctx->fault_wqh))
__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, 0, range);
__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, range);
spin_unlock(&ctx->fault_pending_wqh.lock);
}