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| author |   Daniel De Graaf <dgdegra@tycho.nsa.gov> | 2010-09-08 18:10:42 -0400 |
|---|---|---|
| committer |   Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2010-09-09 10:48:22 +1000 |
| commit | 7808121b9a1e44ef12fecd49fa6c268f27a150fc (patch) | |
| tree | 5536cceff908e630d1a15c4f63abd7210ed4973b /drivers/xen/xenfs | |
| parent | xenbus: add missing wakeup in concurrent read/write (diff) | |
| download | linux-dev-7808121b9a1e44ef12fecd49fa6c268f27a150fc.tar.xz linux-dev-7808121b9a1e44ef12fecd49fa6c268f27a150fc.zip | |
xenbus: avoid zero returns from read()
It is possible to get a zero return from read() in instances where the
queue is not empty but has no elements with data to deliver to the user.
Since a zero return from read is an error indicator, resume waiting or
return -EAGAIN (for a nonblocking fd) in this case.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Diffstat (limited to 'drivers/xen/xenfs')
| -rw-r--r-- | drivers/xen/xenfs/xenbus.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/xen/xenfs/xenbus.c b/drivers/xen/xenfs/xenbus.c index c4c7db8363e7..55791dd1105f 100644 --- a/drivers/xen/xenfs/xenbus.c +++ b/drivers/xen/xenfs/xenbus.c @@ -120,6 +120,7 @@ static ssize_t xenbus_file_read(struct file *filp, int ret; mutex_lock(&u->reply_mutex); +again: while (list_empty(&u->read_buffers)) { mutex_unlock(&u->reply_mutex); if (filp->f_flags & O_NONBLOCK) @@ -158,6 +159,8 @@ static ssize_t xenbus_file_read(struct file *filp, struct read_buffer, list); } } + if (i == 0) + goto again; out: mutex_unlock(&u->reply_mutex); |