From: Johan Hovold <johan@kernel.org>
To: Michael Walle <michael@walle.cc>
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>,
Angelo Dureghello <angelo.dureghello@timesys.com>,
Fugang Duan <fugang.duan@nxp.com>,
Philippe Schenker <philippe.schenker@toradex.com>
Subject: Re: [PATCH 4/8] serial: fsl_lpuart: handle break and make sysrq work
Date: Wed, 12 May 2021 11:30:51 +0200 [thread overview]
Message-ID: <YJugS4fiUBgPvIS6@hovoldconsulting.com> (raw)
In-Reply-To: <20210511200148.11934-5-michael@walle.cc>
On Tue, May 11, 2021 at 10:01:44PM +0200, Michael Walle wrote:
> Although there is already (broken) sysrq characters handling, a break
> condition was never detected. There is also a possible deadlock because
> we might call handle_sysrq() while still holding the port lock.
Where's the possible deadlock?
First, as you point out above the driver currently doesn't detect breaks
so the sysrq handler is never called and there's no risk for deadlocks
in the console code.
Second, the driver's console implementation explicitly handles being
called recursively so would not deadlock after you start detecting
breaks either.
> Add support for break detection and use the proper
> uart_unlock_and_check_sysrq() to defer calling handle_sysrq().
Johan
next prev parent reply other threads:[~2021-05-12 9:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 20:01 [PATCH 0/8] serial: fsl_lpuart: sysrq, loopback support and fixes Michael Walle
2021-05-11 20:01 ` [PATCH 1/8] serial: fsl_lpuart: don't modify arbitrary data on lpuart32 Michael Walle
2021-05-11 20:01 ` [PATCH 2/8] serial: fsl_lpuart: use UARTDATA_MASK macro Michael Walle
2021-05-11 20:01 ` [PATCH 3/8] serial: fsl_lpuart: don't restore interrupt state in ISR Michael Walle
2021-05-12 9:25 ` Johan Hovold
2021-05-12 9:42 ` Michael Walle
2021-05-11 20:01 ` [PATCH 4/8] serial: fsl_lpuart: handle break and make sysrq work Michael Walle
2021-05-12 9:30 ` Johan Hovold [this message]
2021-05-12 9:46 ` Michael Walle
2021-05-12 10:07 ` Johan Hovold
2021-05-12 10:31 ` Michael Walle
2021-05-12 11:18 ` Johan Hovold
2021-05-11 20:01 ` [PATCH 5/8] serial: fsl_lpuart: remove RTSCTS handling from get_mctrl() Michael Walle
2021-05-11 20:01 ` [PATCH 6/8] serial: fsl_lpuart: remove manual RTSCTS control from 8-bit LPUART Michael Walle
2021-05-11 20:01 ` [PATCH 7/8] serial: fsl_lpuart: add loopback support Michael Walle
2021-05-11 20:01 ` [PATCH 8/8] serial: fsl_lpuart: disable DMA for console and fix sysrq Michael Walle
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YJugS4fiUBgPvIS6@hovoldconsulting.com \
--to=johan@kernel.org \
--cc=angelo.dureghello@timesys.com \
--cc=fugang.duan@nxp.com \
--cc=gregkh@linuxfoundation.org \
--cc=jirislaby@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=michael@walle.cc \
--cc=philippe.schenker@toradex.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.