diff options
| author | Volodymyr Babchuk <Volodymyr_Babchuk@epam.com> | 2023-01-19 21:11:15 +0000 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2023-02-13 06:53:20 +0100 |
| commit | c70b7741dda7586529cc270e0f2c4cae3921b9b1 (patch) | |
| tree | 3cbbabb348c4973f18f76818f89d29c27e275a42 /drivers/xen | |
| parent | 3e8cd711c3da6c3d724076048038cd666bdbb2b5 (diff) | |
| download | linux-c70b7741dda7586529cc270e0f2c4cae3921b9b1.tar.gz | |
xen/pvcalls-back: fix permanently masked event channel
There is a sequence of events that can lead to a permanently masked
event channel, because xen_irq_lateeoi() is newer called. This happens
when a backend receives spurious write event from a frontend. In this
case pvcalls_conn_back_write() returns early and it does not clears the
map->write counter. As map->write > 0, pvcalls_back_ioworker() returns
without calling xen_irq_lateeoi(). This leaves the event channel in
masked state, a backend does not receive any new events from a
frontend and the whole communication stops.
Move atomic_set(&map->write, 0) to the very beginning of
pvcalls_conn_back_write() to fix this issue.
Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
Reported-by: Oleksii Moisieiev <oleksii_moisieiev@epam.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20230119211037.1234931-1-volodymyr_babchuk@epam.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/xen')
| -rw-r--r-- | drivers/xen/pvcalls-back.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c index 0d4f8f4f49488..7a464a541d913 100644 --- a/drivers/xen/pvcalls-back.c +++ b/drivers/xen/pvcalls-back.c @@ -173,6 +173,8 @@ static bool pvcalls_conn_back_write(struct sock_mapping *map) RING_IDX cons, prod, size, array_size; int ret; + atomic_set(&map->write, 0); + cons = intf->out_cons; prod = intf->out_prod; /* read the indexes before dealing with the data */ @@ -197,7 +199,6 @@ static bool pvcalls_conn_back_write(struct sock_mapping *map) iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 2, size); } - atomic_set(&map->write, 0); ret = inet_sendmsg(map->sock, &msg, size); if (ret == -EAGAIN) { atomic_inc(&map->write); |