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s390/etr,stp: fix possible deadlock on machine check

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The first level machine check handler for etr and stp machine checks may
call queue_work() while in nmi context. This may deadlock e.g. if the
machine check happened when the interrupted context did hold a lock, that
also will be acquired by queue_work().
Therefore split etr and stp machine check handling into first and second
level handling. The second level handling will then issue the queue_work()
call in process context which avoids the potential deadlock.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2015-10-09 13:48:03 +02:00 • committed by Martin Schwidefsky
parent 7cc8944e13
commit 29b0a8250b
3 changed files with 39 additions and 18 deletions
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31
arch/s390/kernel/time.c
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@ -542,16 +542,17 @@ arch_initcall(etr_init);
* Switch to local machine check. This is called when the last usable
* ETR port goes inactive. After switch to local the clock is not in sync.
*/
void etr_switch_to_local(void)
int etr_switch_to_local(void)
{
if (!etr_eacr.sl)
return;
return 0;
disable_sync_clock(NULL);
if (!test_and_set_bit(ETR_EVENT_SWITCH_LOCAL, &etr_events)) {
etr_eacr.es = etr_eacr.sl = 0;
etr_setr(&etr_eacr);
queue_work(time_sync_wq, &etr_work);
return 1;
}
return 0;
}
/*
@ -560,16 +561,22 @@ void etr_switch_to_local(void)
* After a ETR sync check the clock is not in sync. The machine check
* is broadcasted to all cpus at the same time.
*/
void etr_sync_check(void)
int etr_sync_check(void)
{
if (!etr_eacr.es)
return;
return 0;
disable_sync_clock(NULL);
if (!test_and_set_bit(ETR_EVENT_SYNC_CHECK, &etr_events)) {
etr_eacr.es = 0;
etr_setr(&etr_eacr);
queue_work(time_sync_wq, &etr_work);
return 1;
}
return 0;
}
void etr_queue_work(void)
{
queue_work(time_sync_wq, &etr_work);
}
/*
@ -1504,10 +1511,10 @@ static void stp_timing_alert(struct stp_irq_parm *intparm)
* After a STP sync check the clock is not in sync. The machine check
* is broadcasted to all cpus at the same time.
*/
void stp_sync_check(void)
int stp_sync_check(void)
{
disable_sync_clock(NULL);
queue_work(time_sync_wq, &stp_work);
return 1;
}
/*
@ -1516,12 +1523,16 @@ void stp_sync_check(void)
* have matching CTN ids and have a valid stratum-1 configuration
* but the configurations do not match.
*/
void stp_island_check(void)
int stp_island_check(void)
{
disable_sync_clock(NULL);
queue_work(time_sync_wq, &stp_work);
return 1;
}
void stp_queue_work(void)
{
queue_work(time_sync_wq, &stp_work);
}
static int stp_sync_clock(void *data)
{