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([108.180.130.139]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3957f9ad013sm4853843a91.7.2026.08.19.20.52.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Aug 2026 20:52:04 -0700 (PDT) From: Babanpreet Singh To: Srinivas Kandagatla , Greg Kroah-Hartman , Vinod Koul Cc: Bjorn Andersson , linux-sound@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, Babanpreet Singh Subject: [PATCH] slimbus: qcom-ngd-ctrl: Release the TX descriptor on error paths Date: Thu, 20 Aug 2026 03:52:03 +0000 Message-ID: <20260820035203.7-1-bbnpreetsingh@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit qcom_slim_ngd_xfer_msg() leaks the claimed TX descriptor on two error paths; QCOM_SLIM_NGD_DESC_NUM such failures fill the ring for good and every later transfer fails with -ENOMEM. Give the descriptor back. Fixes: 917809e2280b ("slimbus: ngd: Add qcom SLIMBus NGD driver") Fixes: 52490169cddf ("slimbus: ngd: add stream support") Assisted-by: claude-opus-5 Signed-off-by: Babanpreet Singh --- drivers/slimbus/qcom-ngd-ctrl.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/drivers/slimbus/qcom-ngd-ctrl.c b/drivers/slimbus/qcom-ngd-ctrl.c index 3071e46d03bea..697811b2c1e97 100644 --- a/drivers/slimbus/qcom-ngd-ctrl.c +++ b/drivers/slimbus/qcom-ngd-ctrl.c @@ -546,6 +546,25 @@ static u32 *qcom_slim_ngd_tx_msg_get(struct qcom_slim_ngd_ctrl *ctrl, int len, return desc->base; } +/* + * Give back a descriptor obtained from qcom_slim_ngd_tx_msg_get() that will + * not be submitted to the DMA engine. + * + * The ring is accounted by count rather than by index: tx_tail counts the + * descriptors handed out and tx_head the ones the controller is finished + * with, and qcom_slim_ngd_tx_msg_dma_cb() is the only other place that + * advances tx_head. A descriptor that is never posted therefore has to + * advance it here, or the ring loses that slot for good. + */ +static void qcom_slim_ngd_tx_msg_put(struct qcom_slim_ngd_ctrl *ctrl) +{ + unsigned long flags; + + spin_lock_irqsave(&ctrl->tx_buf_lock, flags); + ctrl->tx_head = (ctrl->tx_head + 1) % QCOM_SLIM_NGD_DESC_NUM; + spin_unlock_irqrestore(&ctrl->tx_buf_lock, flags); +} + static void qcom_slim_ngd_tx_msg_dma_cb(void *args) { struct qcom_slim_ngd_dma_desc *desc = args; @@ -848,6 +867,7 @@ static int qcom_slim_ngd_xfer_msg(struct slim_controller *sctrl, ret = slim_alloc_txn_tid(sctrl, txn); if (ret) { dev_err(ctrl->dev, "Unable to allocate TID\n"); + qcom_slim_ngd_tx_msg_put(ctrl); return ret; } @@ -887,6 +907,7 @@ static int qcom_slim_ngd_xfer_msg(struct slim_controller *sctrl, mutex_lock(&ctrl->tx_lock); ret = qcom_slim_ngd_tx_msg_post(ctrl, pbuf, txn->rl); if (ret) { + qcom_slim_ngd_tx_msg_put(ctrl); mutex_unlock(&ctrl->tx_lock); return ret; } -- 2.43.0