From: Vineeth Vijayan vneethv@linux.ibm.com
[ Upstream commit 0b8eb2ee9da1e8c9b8082f404f3948aa82a057b2 ]
The scanning through subchannels during the time of an event could take significant amount of time in case of platforms with lots of known subchannels. This might result in higher scheduling latencies for other tasks especially on systems with a single CPU. Add cond_resched() call, as the loop in slow_eval_known_fn() can be executed for a longer duration.
Reviewed-by: Peter Oberparleiter oberpar@linux.ibm.com Signed-off-by: Vineeth Vijayan vneethv@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/cio/css.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index df09ed53ab45..825a8f2703b4 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -615,6 +615,11 @@ static int slow_eval_known_fn(struct subchannel *sch, void *data) rc = css_evaluate_known_subchannel(sch, 1); if (rc == -EAGAIN) css_schedule_eval(sch->schid); + /* + * The loop might take long time for platforms with lots of + * known devices. Allow scheduling here. + */ + cond_resched(); } return 0; }