releases/5.1.12/ras-cec-convert-the-timer-callback-to-a-workqueue.patch

   1 From 0ade0b6240c4853cf9725924c46c10f4251639d7 Mon Sep 17 00:00:00 2001
   2 From: Cong Wang <xiyou.wangcong@gmail.com>
   3 Date: Tue, 16 Apr 2019 14:33:51 -0700
   4 Subject: RAS/CEC: Convert the timer callback to a workqueue
   5
   6 From: Cong Wang <xiyou.wangcong@gmail.com>
   7
   8 commit 0ade0b6240c4853cf9725924c46c10f4251639d7 upstream.
   9
  10 cec_timer_fn() is a timer callback which reads ce_arr.array[] and
  11 updates its decay values. However, it runs in interrupt context and the
  12 mutex protection the CEC uses for that array, is inadequate. Convert the
  13 used timer to a workqueue to keep the tasks the CEC performs preemptible
  14 and thus low-prio.
  15
  16  [ bp: Rewrite commit message.
  17    s/timer/decay/gi to make it agnostic as to what facility is used. ]
  18
  19 Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector")
  20 Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
  21 Signed-off-by: Borislav Petkov <bp@suse.de>
  22 Cc: Thomas Gleixner <tglx@linutronix.de>
  23 Cc: Tony Luck <tony.luck@intel.com>
  24 Cc: linux-edac <linux-edac@vger.kernel.org>
  25 Cc: <stable@vger.kernel.org>
  26 Link: https://lkml.kernel.org/r/20190416213351.28999-2-xiyou.wangcong@gmail.com
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  drivers/ras/cec.c |   46 ++++++++++++++++++++++------------------------
  31  1 file changed, 22 insertions(+), 24 deletions(-)
  32
  33 --- a/drivers/ras/cec.c
  34 +++ b/drivers/ras/cec.c
  35 @@ -2,6 +2,7 @@
  36  #include <linux/mm.h>
  37  #include <linux/gfp.h>
  38  #include <linux/kernel.h>
  39 +#include <linux/workqueue.h>
  40
  41  #include <asm/mce.h>
  42
  43 @@ -123,16 +124,12 @@ static u64 dfs_pfn;
  44  /* Amount of errors after which we offline */
  45  static unsigned int count_threshold = COUNT_MASK;
  46
  47 -/*
  48 - * The timer "decays" element count each timer_interval which is 24hrs by
  49 - * default.
  50 - */
  51 -
  52 -#define CEC_TIMER_DEFAULT_INTERVAL     24 * 60 * 60    /* 24 hrs */
  53 -#define CEC_TIMER_MIN_INTERVAL          1 * 60 * 60    /* 1h */
  54 -#define CEC_TIMER_MAX_INTERVAL    30 * 24 * 60 * 60    /* one month */
  55 -static struct timer_list cec_timer;
  56 -static u64 timer_interval = CEC_TIMER_DEFAULT_INTERVAL;
  57 +/* Each element "decays" each decay_interval which is 24hrs by default. */
  58 +#define CEC_DECAY_DEFAULT_INTERVAL     24 * 60 * 60    /* 24 hrs */
  59 +#define CEC_DECAY_MIN_INTERVAL          1 * 60 * 60    /* 1h */
  60 +#define CEC_DECAY_MAX_INTERVAL    30 * 24 * 60 * 60    /* one month */
  61 +static struct delayed_work cec_work;
  62 +static u64 decay_interval = CEC_DECAY_DEFAULT_INTERVAL;
  63
  64  /*
  65   * Decrement decay value. We're using DECAY_BITS bits to denote decay of an
  66 @@ -160,20 +157,21 @@ static void do_spring_cleaning(struct ce
  67  /*
  68   * @interval in seconds
  69   */
  70 -static void cec_mod_timer(struct timer_list *t, unsigned long interval)
  71 +static void cec_mod_work(unsigned long interval)
  72  {
  73         unsigned long iv;
  74
  75 -       iv = interval * HZ + jiffies;
  76 -
  77 -       mod_timer(t, round_jiffies(iv));
  78 +       iv = interval * HZ;
  79 +       mod_delayed_work(system_wq, &cec_work, round_jiffies(iv));
  80  }
  81
  82 -static void cec_timer_fn(struct timer_list *unused)
  83 +static void cec_work_fn(struct work_struct *work)
  84  {
  85 +       mutex_lock(&ce_mutex);
  86         do_spring_cleaning(&ce_arr);
  87 +       mutex_unlock(&ce_mutex);
  88
  89 -       cec_mod_timer(&cec_timer, timer_interval);
  90 +       cec_mod_work(decay_interval);
  91  }
  92
  93  /*
  94 @@ -374,15 +372,15 @@ static int decay_interval_set(void *data
  95  {
  96         *(u64 *)data = val;
  97
  98 -       if (val < CEC_TIMER_MIN_INTERVAL)
  99 +       if (val < CEC_DECAY_MIN_INTERVAL)
 100                 return -EINVAL;
 101
 102 -       if (val > CEC_TIMER_MAX_INTERVAL)
 103 +       if (val > CEC_DECAY_MAX_INTERVAL)
 104                 return -EINVAL;
 105
 106 -       timer_interval = val;
 107 +       decay_interval = val;
 108
 109 -       cec_mod_timer(&cec_timer, timer_interval);
 110 +       cec_mod_work(decay_interval);
 111         return 0;
 112  }
 113  DEFINE_DEBUGFS_ATTRIBUTE(decay_interval_ops, u64_get, decay_interval_set, "%lld\n");
 114 @@ -426,7 +424,7 @@ static int array_dump(struct seq_file *m
 115
 116         seq_printf(m, "Flags: 0x%x\n", ca->flags);
 117
 118 -       seq_printf(m, "Timer interval: %lld seconds\n", timer_interval);
 119 +       seq_printf(m, "Decay interval: %lld seconds\n", decay_interval);
 120         seq_printf(m, "Decays: %lld\n", ca->decays_done);
 121
 122         seq_printf(m, "Action threshold: %d\n", count_threshold);
 123 @@ -472,7 +470,7 @@ static int __init create_debugfs_nodes(v
 124         }
 125
 126         decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d,
 127 -                                   &timer_interval, &decay_interval_ops);
 128 +                                   &decay_interval, &decay_interval_ops);
 129         if (!decay) {
 130                 pr_warn("Error creating decay_interval debugfs node!\n");
 131                 goto err;
 132 @@ -508,8 +506,8 @@ void __init cec_init(void)
 133         if (create_debugfs_nodes())
 134                 return;
 135
 136 -       timer_setup(&cec_timer, cec_timer_fn, 0);
 137 -       cec_mod_timer(&cec_timer, CEC_TIMER_DEFAULT_INTERVAL);
 138 +       INIT_DELAYED_WORK(&cec_work, cec_work_fn);
 139 +       schedule_delayed_work(&cec_work, CEC_DECAY_DEFAULT_INTERVAL);
 140
 141         pr_info("Correctable Errors collector initialized.\n");
 142  }