[PATCH 3.2 13/79] net/9p: Switch to wait_event_killable()

Ben Hutchings
2018-02-11T04:20:06Z

From: Tuomas Tynkkynen <tuomas@tuxera.com>

commit 9523feac272ccad2ad8186ba4fcc89103754de52 upstream.

Because userspace gets Very Unhappy when calls like stat() and execve()
return -EINTR on 9p filesystem mounts. For instance, when bash is
looking in PATH for things to execute and some SIGCHLD interrupts
stat(), bash can throw a spurious 'command not found' since it doesn't
retry the stat().

In practice, hitting the problem is rare and needs a really
slow/bogged down 9p server.

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.2:
- Drop changes in trans_xen.c
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -740,8 +740,7 @@ p9_client_rpc(struct p9_client *c, int8_
goto reterr;
}
/* Wait for the response */
- err = wait_event_interruptible(*req->wq,
- req->status >= REQ_STATUS_RCVD);
+ err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);

if (req->status == REQ_STATUS_ERROR) {
P9_DPRINTK(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -276,8 +276,8 @@ req_retry:
if (err == -ENOSPC) {
chan->ring_bufs_avail = 0;
spin_unlock_irqrestore(&chan->lock, flags);
- err = wait_event_interruptible(*chan->vc_wq,
- chan->ring_bufs_avail);
+ err = wait_event_killable(*chan->vc_wq,
+ chan->ring_bufs_avail);
if (err == -ERESTARTSYS)
return err;

@@ -309,7 +309,7 @@ static int p9_get_mapped_pages(struct vi
* Other zc request to finish here
*/
if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
- err = wait_event_interruptible(vp_wq,
+ err = wait_event_killable(vp_wq,
(atomic_read(&vp_pinned) < chan->p9_max_pages));
if (err == -ERESTARTSYS)
return err;
@@ -419,8 +419,8 @@ req_retry_pinned:
if (err == -ENOSPC) {
chan->ring_bufs_avail = 0;
spin_unlock_irqrestore(&chan->lock, flags);
- err = wait_event_interruptible(*chan->vc_wq,
- chan->ring_bufs_avail);
+ err = wait_event_killable(*chan->vc_wq,
+ chan->ring_bufs_avail);
if (err == -ERESTARTSYS)
goto err_out;

@@ -438,8 +438,7 @@ req_retry_pinned:
virtqueue_kick(chan->vq);
spin_unlock_irqrestore(&chan->lock, flags);
P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
- err = wait_event_interruptible(*req->wq,
- req->status >= REQ_STATUS_RCVD);
+ err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
/*
* Non kernel buffers are pinned, unpin them
*/