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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 <aarcange@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli 2015-09-22 14:58:49 -07:00 committed by Linus Torvalds
parent bcee19f424
commit ac5be6b47e
4 changed files with 10 additions and 12 deletions
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8
fs/userfaultfd.c
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);
}

5
include/linux/wait.h
View File

@ -147,8 +147,7 @@ __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
typedef int wait_bit_action_f(struct wait_bit_key *);
void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, int nr,
void *key);
void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
@ -180,7 +179,7 @@ wait_queue_head_t *bit_waitqueue(void *, int);
#define wake_up_poll(x, m) \
__wake_up(x, TASK_NORMAL, 1, (void *) (m))
#define wake_up_locked_poll(x, m) \
__wake_up_locked_key((x), TASK_NORMAL, 1, (void *) (m))
__wake_up_locked_key((x), TASK_NORMAL, (void *) (m))
#define wake_up_interruptible_poll(x, m) \
__wake_up(x, TASK_INTERRUPTIBLE, 1, (void *) (m))
#define wake_up_interruptible_sync_poll(x, m) \

7
kernel/sched/wait.c
View File

@ -106,10 +106,9 @@ void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr)
}
EXPORT_SYMBOL_GPL(__wake_up_locked);
void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, int nr,
void *key)
void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
{
__wake_up_common(q, mode, nr, 0, key);
__wake_up_common(q, mode, 1, 0, key);
}
EXPORT_SYMBOL_GPL(__wake_up_locked_key);
@ -284,7 +283,7 @@ void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,
if (!list_empty(&wait->task_list))
list_del_init(&wait->task_list);
else if (waitqueue_active(q))
__wake_up_locked_key(q, mode, 1, key);
__wake_up_locked_key(q, mode, key);
spin_unlock_irqrestore(&q->lock, flags);
}
EXPORT_SYMBOL(abort_exclusive_wait);

2
net/sunrpc/sched.c
View File

@ -297,7 +297,7 @@ static int rpc_complete_task(struct rpc_task *task)
clear_bit(RPC_TASK_ACTIVE, &task->tk_runstate);
ret = atomic_dec_and_test(&task->tk_count);
if (waitqueue_active(wq))
__wake_up_locked_key(wq, TASK_NORMAL, 1, &k);
__wake_up_locked_key(wq, TASK_NORMAL, &k);
spin_unlock_irqrestore(&wq->lock, flags);
return ret;
}