src/patches/suse-2.6.27.31/patches.arch/s390-05-06-stp-etr-mutex.patch

   1 From: Gerald Schaefer <geraldsc@de.ibm.com>
   2 Subject: stp/etr: serialize work.
   3 References: bnc#450096
   4
   5 Symptom:     Oops when setting stp online.
   6 Problem:     The stp/etr work function dispatched with schedule_work()
   7              can be run twice on different cpus because run_workqueue
   8              clears the WORK_STRUCT_PENDING bit before it executes the
   9              function.
  10 Solution:    Serialize the etr and stp work functions with a mutex.
  11
  12 Acked-by: John Jolly <jjolly@suse.de>
  13 ---
  14  arch/s390/kernel/time.c |   23 ++++++++++++++++++-----
  15  1 file changed, 18 insertions(+), 5 deletions(-)
  16
  17 Index: linux-2.6.27/arch/s390/kernel/time.c
  18 ===================================================================
  19 --- linux-2.6.27.orig/arch/s390/kernel/time.c
  20 +++ linux-2.6.27/arch/s390/kernel/time.c
  21 @@ -441,6 +441,7 @@ static struct timer_list etr_timer;
  22
  23  static void etr_timeout(unsigned long dummy);
  24  static void etr_work_fn(struct work_struct *work);
  25 +static DEFINE_MUTEX(etr_work_mutex);
  26  static DECLARE_WORK(etr_work, etr_work_fn);
  27
  28  /*
  29 @@ -950,6 +951,9 @@ static void etr_work_fn(struct work_stru
  30         struct etr_aib aib;
  31         int sync_port;
  32
  33 +       /* prevent multiple execution. */
  34 +       mutex_lock(&etr_work_mutex);
  35 +
  36         /* Create working copy of etr_eacr. */
  37         eacr = etr_eacr;
  38
  39 @@ -965,7 +969,7 @@ static void etr_work_fn(struct work_stru
  40                 del_timer_sync(&etr_timer);
  41                 etr_update_eacr(eacr);
  42                 clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);
  43 -               return;
  44 +               goto out_unlock;
  45         }
  46
  47         /* Store aib to get the current ETR status word. */
  48 @@ -1052,7 +1056,7 @@ static void etr_work_fn(struct work_stru
  49             eacr.es || sync_port < 0) {
  50                 etr_update_eacr(eacr);
  51                 etr_set_tolec_timeout(now);
  52 -               return;
  53 +               goto out_unlock;
  54         }
  55
  56         /*
  57 @@ -1080,6 +1084,8 @@ static void etr_work_fn(struct work_stru
  58                 etr_set_sync_timeout();
  59         } else
  60                 etr_set_tolec_timeout(now);
  61 +out_unlock:
  62 +       mutex_unlock(&etr_work_mutex);
  63  }
  64
  65  /*
  66 @@ -1368,6 +1374,7 @@ static struct stp_sstpi stp_info;
  67  static void *stp_page;
  68
  69  static void stp_work_fn(struct work_struct *work);
  70 +static DEFINE_MUTEX(stp_work_mutex);
  71  static DECLARE_WORK(stp_work, stp_work_fn);
  72
  73  static int __init early_parse_stp(char *p)
  74 @@ -1517,24 +1524,30 @@ static void stp_work_fn(struct work_stru
  75         struct clock_sync_data stp_sync;
  76         int rc;
  77
  78 +       /* prevent multiple execution. */
  79 +       mutex_lock(&stp_work_mutex);
  80 +
  81         if (!stp_online) {
  82                 chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000);
  83 -               return;
  84 +               goto out_unlock;
  85         }
  86
  87         rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xb0e0);
  88         if (rc)
  89 -               return;
  90 +               goto out_unlock;
  91
  92         rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
  93         if (rc || stp_info.c == 0)
  94 -               return;
  95 +               goto out_unlock;
  96
  97         memset(&stp_sync, 0, sizeof(stp_sync));
  98         get_online_cpus();
  99         atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
 100         stop_machine(stp_sync_clock, &stp_sync, &cpu_online_map);
 101         put_online_cpus();
 102 +
 103 +out_unlock:
 104 +       mutex_unlock(&stp_work_mutex);
 105  }
 106
 107  /*