releases/3.18.85/net-9p-switch-to-wait_event_killable.patch

   1 From 9523feac272ccad2ad8186ba4fcc89103754de52 Mon Sep 17 00:00:00 2001
   2 From: Tuomas Tynkkynen <tuomas@tuxera.com>
   3 Date: Wed, 6 Sep 2017 17:59:08 +0300
   4 Subject: net/9p: Switch to wait_event_killable()
   5
   6 From: Tuomas Tynkkynen <tuomas@tuxera.com>
   7
   8 commit 9523feac272ccad2ad8186ba4fcc89103754de52 upstream.
   9
  10 Because userspace gets Very Unhappy when calls like stat() and execve()
  11 return -EINTR on 9p filesystem mounts. For instance, when bash is
  12 looking in PATH for things to execute and some SIGCHLD interrupts
  13 stat(), bash can throw a spurious 'command not found' since it doesn't
  14 retry the stat().
  15
  16 In practice, hitting the problem is rare and needs a really
  17 slow/bogged down 9p server.
  18
  19 Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
  20 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22
  23
  24 ---
  25  net/9p/client.c       |    3 +--
  26  net/9p/trans_virtio.c |   13 ++++++-------
  27  2 files changed, 7 insertions(+), 9 deletions(-)
  28
  29 --- a/net/9p/client.c
  30 +++ b/net/9p/client.c
  31 @@ -753,8 +753,7 @@ p9_client_rpc(struct p9_client *c, int8_
  32         }
  33  again:
  34         /* Wait for the response */
  35 -       err = wait_event_interruptible(*req->wq,
  36 -                                      req->status >= REQ_STATUS_RCVD);
  37 +       err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
  38
  39         /*
  40          * Make sure our req is coherent with regard to updates in other
  41 --- a/net/9p/trans_virtio.c
  42 +++ b/net/9p/trans_virtio.c
  43 @@ -292,8 +292,8 @@ req_retry:
  44                 if (err == -ENOSPC) {
  45                         chan->ring_bufs_avail = 0;
  46                         spin_unlock_irqrestore(&chan->lock, flags);
  47 -                       err = wait_event_interruptible(*chan->vc_wq,
  48 -                                                       chan->ring_bufs_avail);
  49 +                       err = wait_event_killable(*chan->vc_wq,
  50 +                                                 chan->ring_bufs_avail);
  51                         if (err  == -ERESTARTSYS)
  52                                 return err;
  53
  54 @@ -324,7 +324,7 @@ static int p9_get_mapped_pages(struct vi
  55                  * Other zc request to finish here
  56                  */
  57                 if (atomic_read(&vp_pinned) >= chan->p9_max_pages) {
  58 -                       err = wait_event_interruptible(vp_wq,
  59 +                       err = wait_event_killable(vp_wq,
  60                               (atomic_read(&vp_pinned) < chan->p9_max_pages));
  61                         if (err == -ERESTARTSYS)
  62                                 return err;
  63 @@ -454,8 +454,8 @@ req_retry_pinned:
  64                 if (err == -ENOSPC) {
  65                         chan->ring_bufs_avail = 0;
  66                         spin_unlock_irqrestore(&chan->lock, flags);
  67 -                       err = wait_event_interruptible(*chan->vc_wq,
  68 -                                                      chan->ring_bufs_avail);
  69 +                       err = wait_event_killable(*chan->vc_wq,
  70 +                                                 chan->ring_bufs_avail);
  71                         if (err  == -ERESTARTSYS)
  72                                 goto err_out;
  73
  74 @@ -472,8 +472,7 @@ req_retry_pinned:
  75         virtqueue_kick(chan->vq);
  76         spin_unlock_irqrestore(&chan->lock, flags);
  77         p9_debug(P9_DEBUG_TRANS, "virtio request kicked\n");
  78 -       err = wait_event_interruptible(*req->wq,
  79 -                                      req->status >= REQ_STATUS_RCVD);
  80 +       err = wait_event_killable(*req->wq, req->status >= REQ_STATUS_RCVD);
  81         /*
  82          * Non kernel buffers are pinned, unpin them
  83          */