From patchwork Thu Jul 4 10:18:04 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 13723567 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B82B13C8FF; Thu, 4 Jul 2024 10:19:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720088361; cv=none; b=WLpNToeMFZoxXVMOAbS96pyNib0KF26F1oxW7W7YI1MNstzblZYKU8ZKhkcKevK/PuSlaCJzZE+vTCMi63BqIISv7bL2Zis3S33tN6k6T/IHCB9klz3vbX52UDVzBmkW+KyPjg8vQ4Di0I3VVNFSRWdzMr8HeMvUvd/oKiXxbjE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720088361; c=relaxed/simple; bh=kB83DN3LYrLXwAxtLBcxkuvnDD4VsSkzzf5MSWSoQiY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=g0faN7PeHzbK+T5zgzWycKAFE/cwwq9GmRoDpIeUUh9QEqsZmCIDut64dO0Oxqn6tTv5OOGqu3gvmxyS9JR6nrddf059zWom0RRcuMrek9wTDGtY/wll+MirJ2nqSUHGkwkgf+MaDTQn9yC9bKWa+iSXdtknQ9dFg9rE31Y/lDA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LRcoAIz2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LRcoAIz2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BDADC4AF0B; Thu, 4 Jul 2024 10:19:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720088361; bh=kB83DN3LYrLXwAxtLBcxkuvnDD4VsSkzzf5MSWSoQiY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LRcoAIz2HOxnmVFe+OKHrBOlXyrVkZl0Fh2jmUuk3PYxAvhRLT73OzBysw8ascY3a DyW4UcICHJsdZl1txFMJZnEXaT/aqX8DhfuUqJxyb3DdcreGTFAQN24jcM01rKKGc/ eK7TTwUnKpiAgIb0Kcb/Sa1eVOQOSZWy7G+lyZCaqbhKMDbnW1vDPg3e/hQfIVEljL WL8T1cz0F/nx6LSXr/4Sup+QVhB2F76FKZN/UPS/c2DUfbGYQZiM5PBh+cb557rmb9 DlItxngq2hG4vHSEw8WTWeY3NZdo+vyK15am4aQQTKjtp7DwfTf5xYaKoF0S6pNn8W Ggw+8OCJx/XPw== Received: from johan by xi.lan with local (Exim 4.97.1) (envelope-from ) id 1sPJYf-000000007zP-11nn; Thu, 04 Jul 2024 12:19:21 +0200 From: Johan Hovold To: Greg Kroah-Hartman , Jiri Slaby Cc: Douglas Anderson , Konrad Dybcio , Bjorn Andersson , linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold , stable@vger.kernel.org Subject: [PATCH v2 2/3] serial: qcom-geni: fix hard lockup on buffer flush Date: Thu, 4 Jul 2024 12:18:04 +0200 Message-ID: <20240704101805.30612-3-johan+linaro@kernel.org> X-Mailer: git-send-email 2.44.1 In-Reply-To: <20240704101805.30612-1-johan+linaro@kernel.org> References: <20240704101805.30612-1-johan+linaro@kernel.org> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The Qualcomm GENI serial driver does not handle buffer flushing and used to continue printing discarded characters when the circular buffer was cleared. Since commit 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo") this instead results in a hard lockup due to qcom_geni_serial_send_chunk_fifo() spinning indefinitely in the interrupt handler. This is easily triggered by interrupting a command such as dmesg in a serial console but can also happen when stopping a serial getty on reboot. Implement the flush_buffer() callback and use it to cancel any active TX command when the write buffer has been emptied. Reported-by: Douglas Anderson Link: https://lore.kernel.org/lkml/20240610222515.3023730-1-dianders@chromium.org/ Fixes: 1788cf6a91d9 ("tty: serial: switch from circ_buf to kfifo") Fixes: a1fee899e5be ("tty: serial: qcom_geni_serial: Fix softlock") Cc: stable@vger.kernel.org # 5.0 Signed-off-by: Johan Hovold --- drivers/tty/serial/qcom_geni_serial.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index a41360d34790..b2bbd2d79dbb 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -906,13 +906,17 @@ static void qcom_geni_serial_handle_tx_fifo(struct uart_port *uport, else pending = kfifo_len(&tport->xmit_fifo); - /* All data has been transmitted and acknowledged as received */ - if (!pending && !status && done) { + /* All data has been transmitted or command has been cancelled */ + if (!pending && done) { qcom_geni_serial_stop_tx_fifo(uport); goto out_write_wakeup; } - avail = port->tx_fifo_depth - (status & TX_FIFO_WC); + if (active) + avail = port->tx_fifo_depth - (status & TX_FIFO_WC); + else + avail = port->tx_fifo_depth; + avail *= BYTES_PER_FIFO_WORD; chunk = min(avail, pending); @@ -1091,6 +1095,11 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport) qcom_geni_serial_cancel_tx_cmd(uport); } +static void qcom_geni_serial_flush_buffer(struct uart_port *uport) +{ + qcom_geni_serial_cancel_tx_cmd(uport); +} + static int qcom_geni_serial_port_setup(struct uart_port *uport) { struct qcom_geni_serial_port *port = to_dev_port(uport); @@ -1547,6 +1556,7 @@ static const struct uart_ops qcom_geni_console_pops = { .request_port = qcom_geni_serial_request_port, .config_port = qcom_geni_serial_config_port, .shutdown = qcom_geni_serial_shutdown, + .flush_buffer = qcom_geni_serial_flush_buffer, .type = qcom_geni_serial_get_type, .set_mctrl = qcom_geni_serial_set_mctrl, .get_mctrl = qcom_geni_serial_get_mctrl,