tree 4a9a1cbad368c1f6c2c79e334c68f8ca04721b98
parent f5cdac274c62ab61874374abb60f2310ab979295
author Martin Schwidefsky <schwidefsky@de.ibm.com> 1280251778 +0200
committer Martin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com> 1280251782 +0200

[S390] etr: fix clock synchronization race

The etr events switch-to-local and sync-check disable the synchronous clock
and schedule a work queue that tries to get the clock back into sync.
If another switch-to-local or sync-check event occurs while the work queue
function etr_work_fn still runs the eacr.es bit and the clock_sync_word can
become inconsistent because check_sync_clock only uses the clock_sync_word
to determine if the clock is in sync or not. The second pass of the
etr_work_fn will reset the eacr.es bit but will leave the clock_sync_word
intact. Fix this race by moving the reset of the eacr.es bit into the
switch-to-local and sync-check functions and by checking the eacr.es bit
as well to decide if the clock needs to be synced.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>