From: Cong Wang xiyou.wangcong@gmail.com
commit 0ade0b6240c4853cf9725924c46c10f4251639d7 upstream.
cec_timer_fn() is a timer callback which reads ce_arr.array[] and updates its decay values. However, it runs in interrupt context and the mutex protection the CEC uses for that array, is inadequate. Convert the used timer to a workqueue to keep the tasks the CEC performs preemptible and thus low-prio.
[ bp: Rewrite commit message. s/timer/decay/gi to make it agnostic as to what facility is used. ]
Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector") Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Signed-off-by: Borislav Petkov bp@suse.de Cc: Thomas Gleixner tglx@linutronix.de Cc: Tony Luck tony.luck@intel.com Cc: linux-edac linux-edac@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20190416213351.28999-2-xiyou.wangcong@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/ras/cec.c | 46 ++++++++++++++++++++++------------------------ 1 file changed, 22 insertions(+), 24 deletions(-)
--- a/drivers/ras/cec.c +++ b/drivers/ras/cec.c @@ -2,6 +2,7 @@ #include <linux/mm.h> #include <linux/gfp.h> #include <linux/kernel.h> +#include <linux/workqueue.h>
#include <asm/mce.h>
@@ -123,16 +124,12 @@ static u64 dfs_pfn; /* Amount of errors after which we offline */ static unsigned int count_threshold = COUNT_MASK;
-/* - * The timer "decays" element count each timer_interval which is 24hrs by - * default. - */ - -#define CEC_TIMER_DEFAULT_INTERVAL 24 * 60 * 60 /* 24 hrs */ -#define CEC_TIMER_MIN_INTERVAL 1 * 60 * 60 /* 1h */ -#define CEC_TIMER_MAX_INTERVAL 30 * 24 * 60 * 60 /* one month */ -static struct timer_list cec_timer; -static u64 timer_interval = CEC_TIMER_DEFAULT_INTERVAL; +/* Each element "decays" each decay_interval which is 24hrs by default. */ +#define CEC_DECAY_DEFAULT_INTERVAL 24 * 60 * 60 /* 24 hrs */ +#define CEC_DECAY_MIN_INTERVAL 1 * 60 * 60 /* 1h */ +#define CEC_DECAY_MAX_INTERVAL 30 * 24 * 60 * 60 /* one month */ +static struct delayed_work cec_work; +static u64 decay_interval = CEC_DECAY_DEFAULT_INTERVAL;
/* * Decrement decay value. We're using DECAY_BITS bits to denote decay of an @@ -160,20 +157,21 @@ static void do_spring_cleaning(struct ce /* * @interval in seconds */ -static void cec_mod_timer(struct timer_list *t, unsigned long interval) +static void cec_mod_work(unsigned long interval) { unsigned long iv;
- iv = interval * HZ + jiffies; - - mod_timer(t, round_jiffies(iv)); + iv = interval * HZ; + mod_delayed_work(system_wq, &cec_work, round_jiffies(iv)); }
-static void cec_timer_fn(struct timer_list *unused) +static void cec_work_fn(struct work_struct *work) { + mutex_lock(&ce_mutex); do_spring_cleaning(&ce_arr); + mutex_unlock(&ce_mutex);
- cec_mod_timer(&cec_timer, timer_interval); + cec_mod_work(decay_interval); }
/* @@ -374,15 +372,15 @@ static int decay_interval_set(void *data { *(u64 *)data = val;
- if (val < CEC_TIMER_MIN_INTERVAL) + if (val < CEC_DECAY_MIN_INTERVAL) return -EINVAL;
- if (val > CEC_TIMER_MAX_INTERVAL) + if (val > CEC_DECAY_MAX_INTERVAL) return -EINVAL;
- timer_interval = val; + decay_interval = val;
- cec_mod_timer(&cec_timer, timer_interval); + cec_mod_work(decay_interval); return 0; } DEFINE_DEBUGFS_ATTRIBUTE(decay_interval_ops, u64_get, decay_interval_set, "%lld\n"); @@ -426,7 +424,7 @@ static int array_dump(struct seq_file *m
seq_printf(m, "Flags: 0x%x\n", ca->flags);
- seq_printf(m, "Timer interval: %lld seconds\n", timer_interval); + seq_printf(m, "Decay interval: %lld seconds\n", decay_interval); seq_printf(m, "Decays: %lld\n", ca->decays_done);
seq_printf(m, "Action threshold: %d\n", count_threshold); @@ -472,7 +470,7 @@ static int __init create_debugfs_nodes(v }
decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d, - &timer_interval, &decay_interval_ops); + &decay_interval, &decay_interval_ops); if (!decay) { pr_warn("Error creating decay_interval debugfs node!\n"); goto err; @@ -508,8 +506,8 @@ void __init cec_init(void) if (create_debugfs_nodes()) return;
- timer_setup(&cec_timer, cec_timer_fn, 0); - cec_mod_timer(&cec_timer, CEC_TIMER_DEFAULT_INTERVAL); + INIT_DELAYED_WORK(&cec_work, cec_work_fn); + schedule_delayed_work(&cec_work, CEC_DECAY_DEFAULT_INTERVAL);
pr_info("Correctable Errors collector initialized.\n"); }