tree 8f13f44d059257470f6a7e783ea74b66c330e926
parent ab6984f5a6d054e1f634dda855b32e5357111974
author Greg Kurz <groug@kaod.org> 1585218763 +0100
committer Alexey Kardashevskiy <aik@ozlabs.ru> 1585270500 +1100

slof: Only close stdout for virtio-serial devices

Recent commit cf28264196e5 fixed an issue where a virtio-serial device
wouldn't shutdown properly during quiesce. The fix is to close stdout
just before quiesce. As expected this causes some messages to not
appear anymore, like the well known ones from prom_init():

Quiescing Open Firmware ...
Booting Linux via __start() @ 0x0000000002000000 ...

Actually all messages are discarded until the OS driver finally takes
control of the device, which may represent a fair amount of logging.
This is suboptimal but this still better than hanging in SLOF.

The hammer is a bit too big though because the change also affects
spapr-vty based consoles, which have no reason to stop working
after quiesce.

Move the hack from the common code to the virtio-serial code so that
it doesn't affect other device types anymore. Register a quiesce hook
that closes stdout in virtio-serial.fs.

While here, as suggested by Segher, bring back some robustness in the
shutdown method.

Reported-by: Fabiano Rosas <farosas@linux.ibm.com>
Fixes: cf28264196e5 "virtio-serial: Rework shutdown sequence"
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>