+From 0ade0b6240c4853cf9725924c46c10f4251639d7 Mon Sep 17 00:00:00 2001
+From: Cong Wang <xiyou.wangcong@gmail.com>
+Date: Tue, 16 Apr 2019 14:33:51 -0700
+Subject: RAS/CEC: Convert the timer callback to a workqueue
+
+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");
+ }