hidma_ll_init() allocates a handoff FIFO, but the matching hidma_ll_uninit() function (which is invoked in remove()) never releases it, leaking memory.
To fix this call kfifo_free in hidma_ll_uninit().
Fixes: d1615ca2e085 ("dmaengine: qcom_hidma: implement lower level hardware interface") Cc: stable@vger.kernel.org Signed-off-by: Qasim Ijaz qasdev00@gmail.com
--- drivers/dma/qcom/hidma_ll.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/dma/qcom/hidma_ll.c b/drivers/dma/qcom/hidma_ll.c index fee448499777..0c2bae46746c 100644 --- a/drivers/dma/qcom/hidma_ll.c +++ b/drivers/dma/qcom/hidma_ll.c @@ -816,6 +816,7 @@ int hidma_ll_uninit(struct hidma_lldev *lldev)
required_bytes = sizeof(struct hidma_tre) * lldev->nr_tres; tasklet_kill(&lldev->task); + kfifo_free(&lldev->handoff_fifo); memset(lldev->trepool, 0, required_bytes); lldev->trepool = NULL; atomic_set(&lldev->pending_tre_count, 0);
On 6/2/25 01:42, Qasim Ijaz wrote:
hidma_ll_init() allocates a handoff FIFO, but the matching hidma_ll_uninit() function (which is invoked in remove()) never releases it, leaking memory.
To fix this call kfifo_free in hidma_ll_uninit().
Fixes: d1615ca2e085 ("dmaengine: qcom_hidma: implement lower level hardware interface") Cc: stable@vger.kernel.org Signed-off-by: Qasim Ijaz qasdev00@gmail.com
drivers/dma/qcom/hidma_ll.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/dma/qcom/hidma_ll.c b/drivers/dma/qcom/hidma_ll.c index fee448499777..0c2bae46746c 100644 --- a/drivers/dma/qcom/hidma_ll.c +++ b/drivers/dma/qcom/hidma_ll.c @@ -816,6 +816,7 @@ int hidma_ll_uninit(struct hidma_lldev *lldev) required_bytes = sizeof(struct hidma_tre) * lldev->nr_tres; tasklet_kill(&lldev->task);
- kfifo_free(&lldev->handoff_fifo); memset(lldev->trepool, 0, required_bytes); lldev->trepool = NULL; atomic_set(&lldev->pending_tre_count, 0);
Is it possible that the handoff_fifo is freed, then we could observe reset complete interrupts before they are being cleared in hidma_ll_uninit later on, which would lead to the following call chain
hidma_ll_inthandler - hidma_ll_int_handler_internal - hidma_handle_tre_completion - hidma_post_completed - tasklet_schedule(&lldev->task); - hidma_ll_tre_complete - kfifo_out
?
On 6/5/2025 9:04 AM, Eugen Hristev wrote:
diff --git a/drivers/dma/qcom/hidma_ll.c b/drivers/dma/qcom/hidma_ll.c index fee448499777..0c2bae46746c 100644 --- a/drivers/dma/qcom/hidma_ll.c +++ b/drivers/dma/qcom/hidma_ll.c @@ -816,6 +816,7 @@ int hidma_ll_uninit(struct hidma_lldev *lldev) required_bytes = sizeof(struct hidma_tre) * lldev->nr_tres; tasklet_kill(&lldev->task);
- kfifo_free(&lldev->handoff_fifo); memset(lldev->trepool, 0, required_bytes); lldev->trepool = NULL; atomic_set(&lldev->pending_tre_count, 0);
Is it possible that the handoff_fifo is freed, then we could observe reset complete interrupts before they are being cleared in hidma_ll_uninit later on, which would lead to the following call chain
hidma_ll_inthandler - hidma_ll_int_handler_internal - hidma_handle_tre_completion - hidma_post_completed - tasklet_schedule(&lldev->task); - hidma_ll_tre_complete - kfifo_out
According to the documentation, the way to guarantee this from not happening
is to call tasklet_disable() to ensure that tasklet completes execution. Only after that
data structures used by the tasklet can be freed.
I think proper order is:
1. tasklet_disable
2. tasklet_kill
3. kfifo_free
On Fri, Jun 06, 2025 at 09:35:44AM -0400, Sinan Kaya wrote:
On 6/5/2025 9:04 AM, Eugen Hristev wrote:
diff --git a/drivers/dma/qcom/hidma_ll.c b/drivers/dma/qcom/hidma_ll.c index fee448499777..0c2bae46746c 100644 --- a/drivers/dma/qcom/hidma_ll.c +++ b/drivers/dma/qcom/hidma_ll.c @@ -816,6 +816,7 @@ int hidma_ll_uninit(struct hidma_lldev *lldev) required_bytes = sizeof(struct hidma_tre) * lldev->nr_tres; tasklet_kill(&lldev->task);
- kfifo_free(&lldev->handoff_fifo); memset(lldev->trepool, 0, required_bytes); lldev->trepool = NULL; atomic_set(&lldev->pending_tre_count, 0);
Is it possible that the handoff_fifo is freed, then we could observe reset complete interrupts before they are being cleared in hidma_ll_uninit later on, which would lead to the following call chain
hidma_ll_inthandler - hidma_ll_int_handler_internal - hidma_handle_tre_completion - hidma_post_completed - tasklet_schedule(&lldev->task); - hidma_ll_tre_complete - kfifo_out
According to the documentation, the way to guarantee this from not happening
is to call tasklet_disable() to ensure that tasklet completes execution. Only after that
data structures used by the tasklet can be freed.
I think proper order is:
tasklet_disable
tasklet_kill
kfifo_free
Hi Sinan, hi Eugen,
Thanks for reviewing the patch and for pointing out the correct shutdown ordering.
If you’re both happy with it, I’ll send a v2 that calls tasklet_disable() before tasklet_kill(), then frees the handoff_fifo.
Just let me know and I’ll resend.
Thanks Qasim
On 6/15/2025 3:15 PM, Qasim Ijaz wrote:
Thanks for reviewing the patch and for pointing out the correct shutdown ordering.
If you’re both happy with it, I’ll send a v2 that calls tasklet_disable() before tasklet_kill(), then frees the handoff_fifo.
Just let me know and I’ll resend.
Sure, please test it on a test kernel module before posting with a tasklet.
This should be straightforward to verify.
linux-stable-mirror@lists.linaro.org
-
Eugen Hristev -
Qasim Ijaz -
Sinan Kaya