From 22b886dd1018093920c4250dee2a9a3cb7cff7b8 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 4 Nov 2015 12:15:33 -0500 Subject: timers: Use proper base migration in add_timer_on() Regardless of the previous CPU a timer was on, add_timer_on() currently simply sets timer->flags to the new CPU. As the caller must be seeing the timer as idle, this is locally fine, but the timer leaving the old base while unlocked can lead to race conditions as follows. Let's say timer was on cpu 0. cpu 0 cpu 1 ----------------------------------------------------------------------------- del_timer(timer) succeeds del_timer(timer) lock_timer_base(timer) locks cpu_0_base add_timer_on(timer, 1) spin_lock(&cpu_1_base->lock) timer->flags set to cpu_1_base operates on @timer operates on @timer This triggered with mod_delayed_work_on() which contains "if (del_timer()) add_timer_on()" sequence eventually leading to the following oops. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] detach_if_pending+0x69/0x1a0 ... Workqueue: wqthrash wqthrash_workfunc [wqthrash] task: ffff8800172ca680 ti: ffff8800172d0000 task.ti: ffff8800172d0000 RIP: 0010:[] [] detach_if_pending+0x69/0x1a0 ... Call Trace: [] del_timer+0x44/0x60 [] try_to_grab_pending+0xb6/0x160 [] mod_delayed_work_on+0x33/0x80 [] wqthrash_workfunc+0x61/0x90 [wqthrash] [] process_one_work+0x1e8/0x650 [] worker_thread+0x4e/0x450 [] kthread+0xef/0x110 [] ret_from_fork+0x3f/0x70 Fix it by updating add_timer_on() to perform proper migration as __mod_timer() does. Reported-and-tested-by: Jeff Layton Signed-off-by: Tejun Heo Cc: Chris Worley Cc: bfields@fieldses.org Cc: Michael Skralivetsky Cc: Trond Myklebust Cc: Shaohua Li Cc: Jeff Layton Cc: kernel-team@fb.com Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20151029103113.2f893924@tlielax.poochiereds.net Link: http://lkml.kernel.org/r/20151104171533.GI5749@mtj.duckdns.org Signed-off-by: Thomas Gleixner --- kernel/time/timer.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 74591ba9474f..bbc5d1114583 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -977,13 +977,29 @@ EXPORT_SYMBOL(add_timer); */ void add_timer_on(struct timer_list *timer, int cpu) { - struct tvec_base *base = per_cpu_ptr(&tvec_bases, cpu); + struct tvec_base *new_base = per_cpu_ptr(&tvec_bases, cpu); + struct tvec_base *base; unsigned long flags; timer_stats_timer_set_start_info(timer); BUG_ON(timer_pending(timer) || !timer->function); - spin_lock_irqsave(&base->lock, flags); - timer->flags = (timer->flags & ~TIMER_BASEMASK) | cpu; + + /* + * If @timer was on a different CPU, it should be migrated with the + * old base locked to prevent other operations proceeding with the + * wrong base locked. See lock_timer_base(). + */ + base = lock_timer_base(timer, &flags); + if (base != new_base) { + timer->flags |= TIMER_MIGRATING; + + spin_unlock(&base->lock); + base = new_base; + spin_lock(&base->lock); + WRITE_ONCE(timer->flags, + (timer->flags & ~TIMER_BASEMASK) | cpu); + } + debug_activate(timer, timer->expires); internal_add_timer(base, timer); spin_unlock_irqrestore(&base->lock, flags); -- cgit v1.2.3 From 4717f133736dec10605da9e29e707144c8d486df Mon Sep 17 00:00:00 2001 From: Grygorii Strashko Date: Tue, 10 Nov 2015 11:58:12 +0200 Subject: genirq/PM: Restore system wake up from chained interrupts Commit e509bd7da149 ("genirq: Allow migration of chained interrupts by installing default action") breaks PCS wake up IRQ behaviour on TI OMAP based platforms (dra7-evm). TI OMAP IRQ wake up configuration: GIC-irqchip->PCM_IRQ |- omap_prcm_register_chain_handler |- PRCM-irqchip -> PRCM_IO_IRQ |- pcs_irq_chain_handler |- pinctrl-irqchip -> PCS_uart1_wakeup_irq This happens because IRQ PM code (irq/pm.c) is expected to ignore chained interrupts by default: static bool suspend_device_irq(struct irq_desc *desc) { if (!desc->action || desc->no_suspend_depth) return false; - it's expected !desc->action = true for chained interrupts; but, after above change, all chained interrupt descriptors will have default action handler installed - chained_action. As result, chained interrupts will be silently disabled during system suspend. Hence, fix it by introducing helper function irq_desc_is_chained() and use it in suspend_device_irq() for chained interrupts identification and skip them, once detected. Fixes: e509bd7da149 ("genirq: Allow migration of chained interrupts..") Signed-off-by: Grygorii Strashko Reviewed-by: Mika Westerberg Cc: Tony Lindgren Cc: Cc: Cc: Tony Lindgren Link: http://lkml.kernel.org/r/1447149492-20699-1-git-send-email-grygorii.strashko@ti.com Signed-off-by: Thomas Gleixner --- kernel/irq/internals.h | 5 +++++ kernel/irq/pm.c | 3 ++- kernel/irq/proc.c | 2 +- 3 files changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index 05c2188271b8..fcab63c66905 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -199,6 +199,11 @@ static inline int irq_desc_get_node(struct irq_desc *desc) return irq_common_data_get_node(&desc->irq_common_data); } +static inline int irq_desc_is_chained(struct irq_desc *desc) +{ + return (desc->action && desc->action == &chained_action); +} + #ifdef CONFIG_PM_SLEEP bool irq_pm_check_wakeup(struct irq_desc *desc); void irq_pm_install_action(struct irq_desc *desc, struct irqaction *action); diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c index 21c62617a35a..84ab239a00e2 100644 --- a/kernel/irq/pm.c +++ b/kernel/irq/pm.c @@ -70,7 +70,8 @@ void irq_pm_remove_action(struct irq_desc *desc, struct irqaction *action) static bool suspend_device_irq(struct irq_desc *desc) { - if (!desc->action || desc->no_suspend_depth) + if (!desc->action || irq_desc_is_chained(desc) || + desc->no_suspend_depth) return false; if (irqd_is_wakeup_set(&desc->irq_data)) { diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c index a916cf144b65..a2c02fd5d6d0 100644 --- a/kernel/irq/proc.c +++ b/kernel/irq/proc.c @@ -475,7 +475,7 @@ int show_interrupts(struct seq_file *p, void *v) for_each_online_cpu(j) any_count |= kstat_irqs_cpu(i, j); action = desc->action; - if ((!action || action == &chained_action) && !any_count) + if ((!action || irq_desc_is_chained(desc)) && !any_count) goto out; seq_printf(p, "%*d: ", prec, i); -- cgit v1.2.3