From: Heiko Carstens Date: Fri, 9 Oct 2015 11:48:03 +0000 (+0200) Subject: s390/etr,stp: fix possible deadlock on machine check X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=29b0a8250ba63beffba4fe3a42fa75dddf4bd06a;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git s390/etr,stp: fix possible deadlock on machine check 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 Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/include/asm/etr.h b/arch/s390/include/asm/etr.h index f7e5c36688c3..105f90e63a0e 100644 --- a/arch/s390/include/asm/etr.h +++ b/arch/s390/include/asm/etr.h @@ -211,8 +211,9 @@ static inline int etr_ptff(void *ptff_block, unsigned int func) #define ETR_PTFF_SGS 0x43 /* set gross steering rate */ /* Functions needed by the machine check handler */ -void etr_switch_to_local(void); -void etr_sync_check(void); +int etr_switch_to_local(void); +int etr_sync_check(void); +void etr_queue_work(void); /* notifier for syncs */ extern struct atomic_notifier_head s390_epoch_delta_notifier; @@ -253,7 +254,8 @@ struct stp_sstpi { } __attribute__ ((packed)); /* Functions needed by the machine check handler */ -void stp_sync_check(void); -void stp_island_check(void); +int stp_sync_check(void); +int stp_island_check(void); +void stp_queue_work(void); #endif /* __S390_ETR_H */ diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index 0ae6f8e74840..4082885dd4fb 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -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 */ diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index 017c3a9bfc28..99f84ac31307 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -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) {