[PATCH 12/33] dmaengine: at_hdmac: Protect atchan->status with the channel lock

Tudor Ambarus
2022-08-20T12:58:57Z

Now that the complete callback call was removed from
device_terminate_all(), we can protect the atchan->status with the channel
lock. The atomic bitops on atchan->status do not substitute proper locking
on the status, as one could still modify the status after the lock was
dropped in atc_terminate_all() but before the atomic bitops were executed.

Fixes: 078a6506141a ("dmaengine: at_hdmac: Fix deadlocks")
Reported-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/
---
drivers/dma/at_hdmac.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index b3895e5d2ae9..aeb241832c52 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -1902,12 +1902,12 @@ static int atc_terminate_all(struct dma_chan *chan)
list_splice_tail_init(&atchan->queue, &atchan->free_list);
list_splice_tail_init(&atchan->active_list, &atchan->free_list);

- spin_unlock_irqrestore(&atchan->lock, flags);
-
clear_bit(ATC_IS_PAUSED, &atchan->status);
/* if channel dedicated to cyclic operations, free it */
clear_bit(ATC_IS_CYCLIC, &atchan->status);

+ spin_unlock_irqrestore(&atchan->lock, flags);
+
return 0;
}

--
2.25.1