fuse: don't hold lock over request_wait_answer()
Only hold fc->lock over sections of request_wait_answer() that actually
need it. If wait_event_interruptible() returns zero, it means that the
request finished. Need to add memory barriers, though, to make sure that
all relevant data in the request is synchronized.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 2014cee..638aafd 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -381,6 +381,7 @@
req->end = NULL;
list_del_init(&req->list);
list_del_init(&req->intr_entry);
+ smp_wmb();
req->state = FUSE_REQ_FINISHED;
if (test_bit(FR_BACKGROUND, &req->flags)) {
clear_bit(FR_BACKGROUND, &req->flags);
@@ -407,19 +408,6 @@
fuse_put_request(fc, req);
}
-static void wait_answer_interruptible(struct fuse_conn *fc,
- struct fuse_req *req)
-__releases(fc->lock)
-__acquires(fc->lock)
-{
- if (signal_pending(current))
- return;
-
- spin_unlock(&fc->lock);
- wait_event_interruptible(req->waitq, req->state == FUSE_REQ_FINISHED);
- spin_lock(&fc->lock);
-}
-
static void queue_interrupt(struct fuse_conn *fc, struct fuse_req *req)
{
list_add_tail(&req->intr_entry, &fc->interrupts);
@@ -428,19 +416,21 @@
}
static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req)
-__releases(fc->lock)
-__acquires(fc->lock)
{
+ int err;
+
if (!fc->no_interrupt) {
/* Any signal may interrupt this */
- wait_answer_interruptible(fc, req);
-
- if (req->state == FUSE_REQ_FINISHED)
+ err = wait_event_interruptible(req->waitq,
+ req->state == FUSE_REQ_FINISHED);
+ if (!err)
return;
+ spin_lock(&fc->lock);
set_bit(FR_INTERRUPTED, &req->flags);
if (req->state == FUSE_REQ_SENT)
queue_interrupt(fc, req);
+ spin_unlock(&fc->lock);
}
if (!test_bit(FR_FORCE, &req->flags)) {
@@ -448,46 +438,51 @@
/* Only fatal signals may interrupt this */
block_sigs(&oldset);
- wait_answer_interruptible(fc, req);
+ err = wait_event_interruptible(req->waitq,
+ req->state == FUSE_REQ_FINISHED);
restore_sigs(&oldset);
- if (req->state == FUSE_REQ_FINISHED)
+ if (!err)
return;
+ spin_lock(&fc->lock);
/* Request is not yet in userspace, bail out */
if (req->state == FUSE_REQ_PENDING) {
list_del(&req->list);
+ spin_unlock(&fc->lock);
__fuse_put_request(req);
req->out.h.error = -EINTR;
return;
}
+ spin_unlock(&fc->lock);
}
/*
* Either request is already in userspace, or it was forced.
* Wait it out.
*/
- spin_unlock(&fc->lock);
wait_event(req->waitq, req->state == FUSE_REQ_FINISHED);
- spin_lock(&fc->lock);
}
static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
{
BUG_ON(test_bit(FR_BACKGROUND, &req->flags));
spin_lock(&fc->lock);
- if (!fc->connected)
+ if (!fc->connected) {
+ spin_unlock(&fc->lock);
req->out.h.error = -ENOTCONN;
- else {
+ } else {
req->in.h.unique = fuse_get_unique(fc);
queue_request(fc, req);
/* acquire extra reference, since request is still needed
after request_end() */
__fuse_get_request(req);
+ spin_unlock(&fc->lock);
request_wait_answer(fc, req);
+ /* Pairs with smp_wmb() in request_end() */
+ smp_rmb();
}
- spin_unlock(&fc->lock);
}
void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)