Commit 0ade0b62 authored by Cong Wang's avatar Cong Wang Committed by Borislav Petkov
Browse files

RAS/CEC: Convert the timer callback to a workqueue 



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: 011d8261 ("RAS: Add a Corrected Errors Collector")
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarBorislav 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
parent f3c74b38

drivers/ras/cec.c

+22 −24
Original line number Diff line number Diff line
@@ -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_array *ca) 
/*

 * @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);

}



/*
@@ -380,15 +378,15 @@ static int decay_interval_set(void *data, u64 val) 
{

	*(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");
@@ -432,7 +430,7 @@ static int array_dump(struct seq_file *m, void *v) 


	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);
@@ -478,7 +476,7 @@ static int __init create_debugfs_nodes(void) 
	}



	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;
@@ -514,8 +512,8 @@ 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");

}

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