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[174.29.1.49]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-84cbd7d4431sm3527487a34.19.2026.10.21.14.18.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Oct 2026 14:18:55 -0700 (PDT) From: James Hilliard Date: Wed, 21 Oct 2026 15:18:48 -0600 Subject: [PATCH] serial: 8250: check DMA channel configuration errors X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261021-submit-serial-8250-dma-config-errors-v1-v1-1-c067587d1ef2@gmail.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/yWNQQ6CMBBFr0Jm7cS2BKJexbAo7QBjpJhpJRjC3 W11MYv38/+bHSIJU4RbtYPQypGXkEGfKnCTDSMh+8xglGm1Mhrju585YZnZJ15Mo9DPFt0SBh6 RRBaJuGr0Td22tRqUu3rItpfQwNvv0737c1Y9yKWiL43eRsJebHBTiVL6nPNhoC3BcXwBOyFfE qoAAAA= X-Change-ID: 20261021-submit-serial-8250-dma-config-errors-v1-d536630f0c9d To: Greg Kroah-Hartman , Jiri Slaby , Heikki Krogerus Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, James Hilliard X-Mailer: b4 0.15.2 serial8250_request_dma() checks channel capabilities but ignores the result of configuring either channel. Those checks do not establish that the provider accepted the requested slave configuration. If it rejects the configuration, startup still selects DMA and later attempts transfers on a channel that was not configured successfully. Return the configuration error after releasing the channels acquired so far. Both the common and OMAP startup paths already fall back to PIO when requesting DMA fails. Check configuration before allocating the receive buffer or mapping the transmit buffer, using the existing unwind paths. Fixes: 9ee4b83e51f7 ("serial: 8250: Add support for dmaengine") Signed-off-by: James Hilliard --- drivers/tty/serial/8250/8250_dma.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c index 1da605cc8601..d6cda9a121c2 100644 --- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -262,7 +262,9 @@ int serial8250_request_dma(struct uart_8250_port *p) goto release_rx; } - dmaengine_slave_config(dma->rxchan, &dma->rxconf); + ret = dmaengine_slave_config(dma->rxchan, &dma->rxconf); + if (ret) + goto release_rx; /* Get a channel for TX */ dma->txchan = dma_request_slave_channel_compat(mask, @@ -282,7 +284,9 @@ int serial8250_request_dma(struct uart_8250_port *p) goto err; } - dmaengine_slave_config(dma->txchan, &dma->txconf); + ret = dmaengine_slave_config(dma->txchan, &dma->txconf); + if (ret) + goto err; rx_dev = dmaengine_get_dma_device(dma->rxchan); tx_dev = dmaengine_get_dma_device(dma->txchan); --- base-commit: 1184f87e2790e8af9be3116f608d2e86b4792d7d change-id: 20261021-submit-serial-8250-dma-config-errors-v1-d536630f0c9d Best regards, -- James Hilliard