From 9aaef96f61d93062556d34e15731f7d5869dd82e Mon Sep 17 00:00:00 2001 From: Hidetoshi Seto Date: Fri, 17 Jun 2011 04:40:36 -0400 Subject: [PATCH] x86, mce: Do not call del_timer_sync() in IRQ context del_timer_sync() can cause a deadlock when called in interrupt context. It is used with on_each_cpu() in some parts for sysfs files like bank*, check_interval, cmci_disabled and ignore_ce. However, use of on_each_cpu() results in calling the function passed as the argument in interrupt context. This causes a flood of nested warnings from del_timer_sync() (it runs on each CPU) caused even by a simple file access like: $ echo 300 > /sys/devices/system/machinecheck/machinecheck0/check_interval Fortunately, these MCE-specific files are rarely used and AFAIK only few MCE geeks experience this warning. To remove the warning, move timer deletion outside of the interrupt context. Signed-off-by: Hidetoshi Seto Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/mcheck/mce.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 08363b042122..5b5cceec94c5 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1140,6 +1140,15 @@ static void mce_start_timer(unsigned long data) add_timer_on(t, smp_processor_id()); } +/* Must not be called in IRQ context where del_timer_sync() can deadlock */ +static void mce_timer_delete_all(void) +{ + int cpu; + + for_each_online_cpu(cpu) + del_timer_sync(&per_cpu(mce_timer, cpu)); +} + static void mce_do_trigger(struct work_struct *work) { call_usermodehelper(mce_helper, mce_helper_argv, NULL, UMH_NO_WAIT); @@ -1750,7 +1759,6 @@ static struct syscore_ops mce_syscore_ops = { static void mce_cpu_restart(void *data) { - del_timer_sync(&__get_cpu_var(mce_timer)); if (!mce_available(__this_cpu_ptr(&cpu_info))) return; __mcheck_cpu_init_generic(); @@ -1760,16 +1768,15 @@ static void mce_cpu_restart(void *data) /* Reinit MCEs after user configuration changes */ static void mce_restart(void) { + mce_timer_delete_all(); on_each_cpu(mce_cpu_restart, NULL, 1); } /* Toggle features for corrected errors */ -static void mce_disable_ce(void *all) +static void mce_disable_cmci(void *data) { if (!mce_available(__this_cpu_ptr(&cpu_info))) return; - if (all) - del_timer_sync(&__get_cpu_var(mce_timer)); cmci_clear(); } @@ -1852,7 +1859,8 @@ static ssize_t set_ignore_ce(struct sys_device *s, if (mce_ignore_ce ^ !!new) { if (new) { /* disable ce features */ - on_each_cpu(mce_disable_ce, (void *)1, 1); + mce_timer_delete_all(); + on_each_cpu(mce_disable_cmci, NULL, 1); mce_ignore_ce = 1; } else { /* enable ce features */ @@ -1875,7 +1883,7 @@ static ssize_t set_cmci_disabled(struct sys_device *s, if (mce_cmci_disabled ^ !!new) { if (new) { /* disable cmci */ - on_each_cpu(mce_disable_ce, NULL, 1); + on_each_cpu(mce_disable_cmci, NULL, 1); mce_cmci_disabled = 1; } else { /* enable cmci */