linux-kernel - [PATCH v2] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual

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Message-Id: <20221230001404.10902-1-nfrayer@baylibre.com>
Date:   Fri, 30 Dec 2022 01:14:04 +0100
From:   Nicolas Frayer <nfrayer@...libre.com>
To:     peter.ujfalusi@...il.com, nm@...com, ssantosh@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        grygorii.strashko@...com, khilman@...libre.com,
        glaroque@...libre.com, mkorpershoek@...libre.com,
        nfrayer@...libre.com
Subject: [PATCH v2] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual_ring()

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@...libre.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@...il.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