xen/pvcalls-back: fix permanently masked event channel

Browse source

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>

...

This commit is contained in:

Volodymyr Babchuk 2023-01-19 21:11:15 +00:00 • committed by Juergen Gross

parent 3e8cd711c3

commit c70b7741dd

1 changed files with 2 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

3

drivers/xen/pvcalls-back.c

View file