From: Martin Schwidefsky <[email protected]>
The work function dispatched with schedule_work() can be run twice
on different cpus because run_workqueue clears the WORK_STRUCT_PENDING
bit and then executes the function. Another cpu can call schedule_work()
again and run the work function a second time before the first call
is completed. This patch serialized the etr and stp work function with
a mutex.
Signed-off-by: Martin Schwidefsky <[email protected]>
---
arch/s390/kernel/time.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
Index: quilt-2.6/arch/s390/kernel/time.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/time.c
+++ quilt-2.6/arch/s390/kernel/time.c
@@ -467,6 +467,7 @@ static struct timer_list etr_timer;
static void etr_timeout(unsigned long dummy);
static void etr_work_fn(struct work_struct *work);
+static DEFINE_MUTEX(etr_work_mutex);
static DECLARE_WORK(etr_work, etr_work_fn);
/*
@@ -976,6 +977,9 @@ static void etr_work_fn(struct work_stru
struct etr_aib aib;
int sync_port;
+ /* prevent multiple execution. */
+ mutex_lock(&etr_work_mutex);
+
/* Create working copy of etr_eacr. */
eacr = etr_eacr;
@@ -991,7 +995,7 @@ static void etr_work_fn(struct work_stru
del_timer_sync(&etr_timer);
etr_update_eacr(eacr);
clear_bit(CLOCK_SYNC_ETR, &clock_sync_flags);
- return;
+ goto out_unlock;
}
/* Store aib to get the current ETR status word. */
@@ -1078,7 +1082,7 @@ static void etr_work_fn(struct work_stru
eacr.es || sync_port < 0) {
etr_update_eacr(eacr);
etr_set_tolec_timeout(now);
- return;
+ goto out_unlock;
}
/*
@@ -1106,6 +1110,8 @@ static void etr_work_fn(struct work_stru
etr_set_sync_timeout();
} else
etr_set_tolec_timeout(now);
+out_unlock:
+ mutex_unlock(&etr_work_mutex);
}
/*
@@ -1394,6 +1400,7 @@ static struct stp_sstpi stp_info;
static void *stp_page;
static void stp_work_fn(struct work_struct *work);
+static DEFINE_MUTEX(stp_work_mutex);
static DECLARE_WORK(stp_work, stp_work_fn);
static int __init early_parse_stp(char *p)
@@ -1542,24 +1549,30 @@ static void stp_work_fn(struct work_stru
struct clock_sync_data stp_sync;
int rc;
+ /* prevent multiple execution. */
+ mutex_lock(&stp_work_mutex);
+
if (!stp_online) {
chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000);
- return;
+ goto out_unlock;
}
rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xb0e0);
if (rc)
- return;
+ goto out_unlock;
rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
if (rc || stp_info.c == 0)
- return;
+ goto out_unlock;
memset(&stp_sync, 0, sizeof(stp_sync));
get_online_cpus();
atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
stop_machine(stp_sync_clock, &stp_sync, &cpu_online_map);
put_online_cpus();
+
+out_unlock:
+ mutex_unlock(&stp_work_mutex);
}
/*
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.