Message-ID: <sashiko-outbox-206204@kernel.org>
From: sashiko-bot@kernel.org
Subject: Re: [PATCH v11 6/8] serial: 8250: drain canceled TX DMA before
 reusing its buffer
Reply-To: sashiko-reviews@lists.linux.dev
To: "James Hilliard" <james.hilliard1@gmail.com>
Cc: linux-serial@vger.kernel.org
In-Reply-To: <20261109-submit-serial-8250-dma-cancel-v1-v11-6-6364edca63d6@gmail.com>
References: <20261109-submit-serial-8250-dma-cancel-v1-v11-0-6364edca63d6@gmail.com>
 <20261109-submit-serial-8250-dma-cancel-v1-v11-6-6364edca63d6@gmail.com>
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Date: Tue, 10 Nov 2026 04:29:44 +0000
Precedence: list

> uart_flush_buffer() resets the transmit kfifo before calling the driver.
> serial8250_tx_dma_flush() terminates DMA asynchronously and clears
> tx_running, allowing a new write to replace tx_size while a detached
> callback has not yet run. That callback can then consume bytes
> from the new transmission. Reusing the reset kfifo can also overwrite the
> source of a transfer that has not stopped yet.
>=20
> Reserve the flushed FIFO storage through serial core before returning
> from the flush callback. Keep tx_running set until a worker synchronizes
> the terminated channel, suppressing old callbacks and new submissions
> during that interval. Return the mapping to CPU ownership before releasing
> the reservation and waking writers. Normal transfers continue to use the
> FIFO directly.
>=20
> Reuse the locked completion processing after retirement, including OMAP
> [ ... ]
> that guarantee for controllers which previously lacked it.
>=20
> Fixes: a424a34b8fad ("serial: 8250: Fix TX deadlock when using DMA")
> Reviewed-by: Raul E Rangel <rrangel@chromium.org>
> Signed-off-by: James Hilliard <james.hilliard1@gmail.com>

Sashiko has reviewed this patch and found no issues.

--=20
Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261109-submit-ser=
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