Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Nicolas Frayer <nfrayer@baylibre.com>
To:     peter.ujfalusi@gmail.com, nm@ti.com, ssantosh@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        grygorii.strashko@ti.com, khilman@baylibre.com,
        glaroque@baylibre.com, mkorpershoek@baylibre.com,
        nfrayer@baylibre.com
Subject: [PATCH v2] soc: ti: k3-ringacc: Add try_module_get() to k3_dmaring_request_dual_ring()
Date:   Fri, 30 Dec 2022 01:14:04 +0100
Message-Id: <20221230001404.10902-1-nfrayer@baylibre.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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