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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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16
arch/s390/kernel/nmi.c
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@@ -28,6 +28,8 @@ struct mcck_struct {
int kill_task;
int channel_report;
int warning;
unsigned int etr_queue : 1;
unsigned int stp_queue : 1;
unsigned long long mcck_code;
};
@@ -81,6 +83,10 @@ void s390_handle_mcck(void)
if (xchg(&mchchk_wng_posted, 1) == 0)
kill_cad_pid(SIGPWR, 1);
}
if (mcck.etr_queue)
etr_queue_work();
if (mcck.stp_queue)
stp_queue_work();
if (mcck.kill_task) {
local_irq_enable();
printk(KERN_EMERG "mcck: Terminating task because of machine "
@@ -323,13 +329,15 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
if (mci->ed && mci->ec) {
/* External damage */
if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
etr_sync_check();
mcck->etr_queue |= etr_sync_check();
if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
etr_switch_to_local();
mcck->etr_queue |= etr_switch_to_local();
if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
stp_sync_check();
mcck->stp_queue |= stp_sync_check();
if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
stp_island_check();
mcck->stp_queue |= stp_island_check();
if (mcck->etr_queue || mcck->stp_queue)
set_cpu_flag(CIF_MCCK_PENDING);
}
if (mci->se)
/* Storage error uncorrected */