4.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Josef Bacik <jbacik@xxxxxx>
commit 32e67a3a06b88904155170560b7a63d372b320bd upstream.
If you do not set sk_sndtimeo you will get -ERESTARTSYS if there is a
pending signal when you enter sendmsg, which we handle properly.
However if you set a timeout for your commands we'll set sk_sndtimeo to
that timeout, which means that sendmsg will start returning -EINTR
instead of -ERESTARTSYS. Fix this by checking either cases and doing
the correct thing.
Fixes: dc88e34d69d8 ("nbd: set sk->sk_sndtimeo for our sockets")
Reported-and-tested-by: Daniel Xu <dlxu@xxxxxx>
Signed-off-by: Josef Bacik <jbacik@xxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/nbd.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -386,6 +386,15 @@ static int sock_xmit(struct nbd_device *
return result;
}
+/*
+ * Different settings for sk->sk_sndtimeo can result in different return values
+ * if there is a signal pending when we enter sendmsg, because reasons?
+ */
+static inline int was_interrupted(int result)
+{
+ return result == -ERESTARTSYS || result == -EINTR;
+}
+
/* always call with the tx_lock held */
static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
{
@@ -458,7 +467,7 @@ static int nbd_send_cmd(struct nbd_devic
result = sock_xmit(nbd, index, 1, &from,
(type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
if (result <= 0) {
- if (result == -ERESTARTSYS) {
+ if (was_interrupted(result)) {
/* If we havne't sent anything we can just return BUSY,
* however if we have sent something we need to make
* sure we only allow this req to be sent until we are
@@ -502,7 +511,7 @@ send_pages:
}
result = sock_xmit(nbd, index, 1, &from, flags, &sent);
if (result <= 0) {
- if (result == -ERESTARTSYS) {
+ if (was_interrupted(result)) {
/* We've already sent the header, we
* have no choice but to set pending and
* return BUSY.