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dma-mapping: benchmark: fix up kthread-related error handling 

kthread creation failure is invalidly handled inside do_map_benchmark().
The put_task_struct() calls on the error path are supposed to balance the
get_task_struct() calls which only happen after all the kthreads are
successfully created. Rollback using kthread_stop() for already created
kthreads in case of such failure.

In normal situation call kthread_stop_put() to gracefully stop kthreads
and put their task refcounts. This should be done for all started
kthreads.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 65789daa80 ("dma-mapping: add benchmark support for streaming DMA APIs")
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Fedor Pchelkin 2024-05-04 14:47:01 +03:00 committed by Christoph Hellwig
parent c760b3725e
commit bb9025f443
1 changed files with 10 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
kernel/dma/map_benchmark.c
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@ -118,6 +118,8 @@ static int do_map_benchmark(struct map_benchmark_data *map)
if (IS_ERR(tsk[i])) {
pr_err("create dma_map thread failed\n");
ret = PTR_ERR(tsk[i]);
while (--i >= 0)
kthread_stop(tsk[i]);
goto out;
}
@ -139,13 +141,17 @@ 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_put(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;
@ -170,8 +176,6 @@ static int do_map_benchmark(struct map_benchmark_data *map)
}
out:
for (i = 0; i < threads; i++)
put_task_struct(tsk[i]);
put_device(map->dev);
kfree(tsk);
return ret;