Re: [PATCH v2] dma-buf: handle testing kthreads creation failure

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Am 22.05.24 um 20:33 schrieb T.J. Mercier:
On Wed, May 22, 2024 at 11:14 AM Fedor Pchelkin <pchelkin@xxxxxxxxx> wrote:
kthread creation may possibly fail inside race_signal_callback(). In
such a case stop the already started threads, put the already taken
references to them and return with error code.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 2989f6451084 ("dma-buf: Add selftests for dma-fence")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Reviewed-by: T.J. Mercier <tjmercier@xxxxxxxxxx>

Just FYI: I've picked this one up and pushed it to drm-misc-fixes.

Regards,
Christian.

---
v2: use kthread_stop_put() to actually put the last reference as
     T.J. Mercier noticed;
     link to v1: https://lore.kernel.org/lkml/20240522122326.696928-1-pchelkin@xxxxxxxxx/

  drivers/dma-buf/st-dma-fence.c | 6 ++++++
  1 file changed, 6 insertions(+)

diff --git a/drivers/dma-buf/st-dma-fence.c b/drivers/dma-buf/st-dma-fence.c
index b7c6f7ea9e0c..6a1bfcd0cc21 100644
--- a/drivers/dma-buf/st-dma-fence.c
+++ b/drivers/dma-buf/st-dma-fence.c
@@ -540,6 +540,12 @@ static int race_signal_callback(void *arg)
                         t[i].before = pass;
                         t[i].task = kthread_run(thread_signal_callback, &t[i],
                                                 "dma-fence:%d", i);
+                       if (IS_ERR(t[i].task)) {
+                               ret = PTR_ERR(t[i].task);
+                               while (--i >= 0)
+                                       kthread_stop_put(t[i].task);
+                               return ret;
+                       }
                         get_task_struct(t[i].task);
                 }

--
2.39.2






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