4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit e6587cdbd732eacb4c7ce592ed46f7bbcefb655f ]

When a connection is closing we receive on pvcalls_sk_state_change
notification. Instead of setting the connection as closed immediately
(-ENOTCONN), let's read one more time from it: pvcalls_conn_back_read
will set the connection as closed when necessary.

That way, we avoid races between pvcalls_sk_state_change and
pvcalls_back_ioworker.

Signed-off-by: Stefano Stabellini <stefa...@xilinx.com>
Reviewed-by: Boris Ostrovsky <boris.ostrov...@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrov...@oracle.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/xen/pvcalls-back.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 169293c25a915..7185ebb63bd53 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -164,9 +164,10 @@ static void pvcalls_conn_back_read(void *opaque)
 
        /* write the data, then modify the indexes */
        virt_wmb();
-       if (ret < 0)
+       if (ret < 0) {
+               atomic_set(&map->read, 0);
                intf->in_error = ret;
-       else
+       } else
                intf->in_prod = prod + ret;
        /* update the indexes, then notify the other end */
        virt_wmb();
@@ -296,7 +297,7 @@ static void pvcalls_sk_state_change(struct sock *sock)
                return;
 
        intf = map->ring;
-       intf->in_error = -ENOTCONN;
+       atomic_inc(&map->read);
        notify_remote_via_irq(map->irq);
 }
 
-- 
2.19.1



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