[PATCH 2/2] dma-mapping: benchmark: prevent potential kthread hang

[Fedor Pchelkin]

If some of kthreads executing map_benchmark_thread() return with an error
code (e.g. due to a memory allocation failure), then the next kthreads in
the array are not stopped and potentially loop for indefinite time.

Call kthread_stop() for each started thread as map_benchmark_thread()
expects that happening in order to exit.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 65789daa8087 ("dma-mapping: add benchmark support for streaming DMA APIs")
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
---
 kernel/dma/map_benchmark.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/kernel/dma/map_benchmark.c b/kernel/dma/map_benchmark.c
index ea938bc6c7e3..7e39a4690331 100644
--- a/kernel/dma/map_benchmark.c
+++ b/kernel/dma/map_benchmark.c
@@ -140,13 +140,17 @@ static int do_map_benchmark(struct map_benchmark_data *map)
 
 	msleep_interruptible(map->bparam.seconds * 1000);
 
-	/* wait for the completion of benchmark threads */
+	/* wait for the completion of all started benchmark threads */
 	for (i = 0; i < threads; i++) {
-		ret = kthread_stop(tsk[i]);
-		if (ret)
-			goto out;
+		int kthread_ret = kthread_stop(tsk[i]);
+
+		if (kthread_ret)
+			ret = kthread_ret;
 	}
 
+	if (ret)
+		goto out;
+
 	loops = atomic64_read(&map->loops);
 	if (likely(loops > 0)) {
 		u64 map_variance, unmap_variance;
-- 
2.45.0