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Commit 0b3016b7 authored by Martin Schwidefsky's avatar Martin Schwidefsky
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[S390] serialize stp/etr work 



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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 750887de

arch/s390/kernel/time.c

+18 −5
Original line number Diff line number Diff line
@@ -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_struct *work) 
	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_struct *work) 
		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_struct *work) 
	    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_struct *work) 
		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_struct *work) 
	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);

}



/*