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| author | jiangyiwen <jiangyiwen@huawei.com> | 2018-07-19 15:17:00 +0800 |
|---|---|---|
| committer | Dominique Martinet <dominique.martinet@cea.fr> | 2018-08-13 09:34:58 +0900 |
| commit | 31934da810365f603dec5a67e690e00cf900fc73 (patch) | |
| tree | 634da305fd1364db1b0dc838cb37b908cb870944 /net/9p | |
| parent | c7ebbae7cf9c50253a978f25d72d16e012bd46f1 (diff) | |
| download | linux-31934da810365f603dec5a67e690e00cf900fc73.tar.gz linux-31934da810365f603dec5a67e690e00cf900fc73.tar.bz2 linux-31934da810365f603dec5a67e690e00cf900fc73.zip | |
net/9p/virtio: Fix hard lockup in req_done
When client has multiple threads that issue io requests
all the time, and the server has a very good performance,
it may cause cpu is running in the irq context for a long
time because it can check virtqueue has buf in the *while*
loop.
So we should keep chan->lock in the whole loop.
[ Dominique: reworded subject line ]
Link: http://lkml.kernel.org/r/5B503AEC.5080404@huawei.com
Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>
To: Eric Van Hensbergen <ericvh@gmail.com>
To: Ron Minnich <rminnich@sandia.gov>
To: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Diffstat (limited to 'net/9p')
| -rw-r--r-- | net/9p/trans_virtio.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index c5464ec311fe..d422bfc81eca 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -144,24 +144,25 @@ static void req_done(struct virtqueue *vq) struct virtio_chan *chan = vq->vdev->priv; unsigned int len; struct p9_req_t *req; + bool need_wakeup = false; unsigned long flags; p9_debug(P9_DEBUG_TRANS, ": request done\n"); - while (1) { - spin_lock_irqsave(&chan->lock, flags); - req = virtqueue_get_buf(chan->vq, &len); - if (req == NULL) { - spin_unlock_irqrestore(&chan->lock, flags); - break; + spin_lock_irqsave(&chan->lock, flags); + while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) { + if (!chan->ring_bufs_avail) { + chan->ring_bufs_avail = 1; + need_wakeup = true; } - chan->ring_bufs_avail = 1; - spin_unlock_irqrestore(&chan->lock, flags); - /* Wakeup if anyone waiting for VirtIO ring space. */ - wake_up(chan->vc_wq); + if (len) p9_client_cb(chan->client, req, REQ_STATUS_RCVD); } + spin_unlock_irqrestore(&chan->lock, flags); + /* Wakeup if anyone waiting for VirtIO ring space. */ + if (need_wakeup) + wake_up(chan->vc_wq); } /** |