pvcalls-back: set -ENOTCONN in pvcalls_conn_back_read

BugLink: https://bugs.launchpad.net/bugs/1837813
[ 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 <stefanos@xilinx.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index f3289ff3a4d805c06d7a4efee26ae8f02c4f60a4..1c508e66b5691fcd5a4daa3eeac97636d8bb4b5e 100644 (file)
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -160,9 +160,10 @@ 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();
@@ -288,7 +289,7 @@ 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);
 }