[PATCH 3.16 225/357] iio: meter: ade7758: Fix indio_dev->trig assignment

[Greg Kroah-Hartman]

3.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>

commit 0495081179212b758775df752e657ea71dcae020 upstream.

This can result in wrong reference count for trigger device, call
iio_trigger_get to increment reference.
Refer to http://www.spinics.net/lists/linux-iio/msg13669.html for discussion
with Jonathan.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
Acked-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/staging/iio/meter/ade7758_trigger.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/iio/meter/ade7758_trigger.c
+++ b/drivers/staging/iio/meter/ade7758_trigger.c
@@ -85,7 +85,7 @@ int ade7758_probe_trigger(struct iio_dev
 	ret = iio_trigger_register(st->trig);
 
 	/* select default trigger */
-	indio_dev->trig = st->trig;
+	indio_dev->trig = iio_trigger_get(st->trig);
 	if (ret)
 		goto error_free_irq;
 


tm_page_alloc.c
@@ -391,14 +391,17 @@ out:
 static unsigned long
 ttm_pool_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 {
-	static atomic_t start_pool = ATOMIC_INIT(0);
+	static DEFINE_MUTEX(lock);
+	static unsigned start_pool;
 	unsigned i;
-	unsigned pool_offset = atomic_add_return(1, &start_pool);
+	unsigned pool_offset;
 	struct ttm_page_pool *pool;
 	int shrink_pages = sc->nr_to_scan;
 	unsigned long freed = 0;
 
-	pool_offset = pool_offset % NUM_POOLS;
+	if (!mutex_trylock(&lock))
+		return SHRINK_STOP;
+	pool_offset = ++start_pool % NUM_POOLS;
 	/* select start pool in round robin fashion */
 	for (i = 0; i < NUM_POOLS; ++i) {
 		unsigned nr_free = shrink_pages;
@@ -408,6 +411,7 @@ ttm_pool_shrink_scan(struct shrinker *sh
 		shrink_pages = ttm_page_pool_free(pool, nr_free);
 		freed += nr_free - shrink_pages;
 	}
+	mutex_unlock(&lock);
 	return freed;
 }
 


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