[PATCH v2] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual_ring()

[PATCH v2] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual_ring()

[Nicolas Frayer]

When the k3 ring accelerator driver has been modified to add module build
support, try_module_get() and module_put() have been added to update the
module refcnt. One code path has not been updated and it has introduced
an issue where the refcnt is decremented by module_put() in
k3_ringacc_ring_free() without being incremented previously.
Adding try_module_get() to k3_dmaring_request_dual_ring() ensures the
refcnt is kept up to date.

Fixes: c07f216a8b72 ("soc: ti: k3-ringacc: Allow the driver to be built as module")
Signed-off-by: Nicolas Frayer <nfrayer@baylibre.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
---
v1->v2:
Added the Fixes and Reviewed-by tags

 drivers/soc/ti/k3-ringacc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/soc/ti/k3-ringacc.c b/drivers/soc/ti/k3-ringacc.c
index e01e4d815230a..8f131368a7586 100644
--- a/drivers/soc/ti/k3-ringacc.c
+++ b/drivers/soc/ti/k3-ringacc.c
@@ -406,6 +406,11 @@ static int k3_dmaring_request_dual_ring(struct k3_ringacc *ringacc, int fwd_id,
 
 	mutex_lock(&ringacc->req_lock);
 
+	if (!try_module_get(ringacc->dev->driver->owner)) {
+		ret = -EINVAL;
+		goto err_module_get;
+	}
+
 	if (test_bit(fwd_id, ringacc->rings_inuse)) {
 		ret = -EBUSY;
 		goto error;
@@ -421,6 +426,8 @@ static int k3_dmaring_request_dual_ring(struct k3_ringacc *ringacc, int fwd_id,
 	return 0;
 
 error:
+	module_put(ringacc->dev->driver->owner);
+err_module_get:
 	mutex_unlock(&ringacc->req_lock);
 	return ret;
 }
-- 
2.25.1

Re: [PATCH v2] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual_ring()

[Nishanth Menon]

Hi Nicolas Frayer,

On Fri, 30 Dec 2022 01:14:04 +0100, Nicolas Frayer wrote:
> When the k3 ring accelerator driver has been modified to add module build
> support, try_module_get() and module_put() have been added to update the
> module refcnt. One code path has not been updated and it has introduced
> an issue where the refcnt is decremented by module_put() in
> k3_ringacc_ring_free() without being incremented previously.
> Adding try_module_get() to k3_dmaring_request_dual_ring() ensures the
> refcnt is kept up to date.
> 
> [...]

I have applied the following to branch ti-drivers-soc-next on [1].
Thank you!

[1/1] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual_ring()
      commit: 5f1732a8683c1da8faaa90d6ffc3bd6d33013a58

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent up the chain during
the next merge window (or sooner if it is a relevant bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

[1] git://git.kernel.org/pub/scm/linux/kernel/git/ti/linux.git
-- 
Regards,
Nishanth Menon
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