From: Tobias Klauser <tklauser@distanz.ch>
To: Johan Hovold <johan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 02/26] serial: altera_jtaguart: drop low-latency workaround
Date: Wed, 21 Apr 2021 12:03:52 +0200 [thread overview]
Message-ID: <20210421100352.vayt5himhl7php4h@distanz.ch> (raw)
In-Reply-To: <20210421095509.3024-3-johan@kernel.org>
On 2021-04-21 at 11:54:45 +0200, Johan Hovold <johan@kernel.org> wrote:
> Commit 53dd0ba7a6f4 ("tty: serial: altera_jtag: drop uart_port->lock
> before calling tty_flip_buffer_push()") claimed to address a locking
> issue but only provided a dubious lockdep splat from an unrelated
> driver, which in the end turned out to be due a broken local change
> carried by the author.
>
> Unfortunately these patches were merged before the issue had been
> analysed properly so the commit messages makes no sense whatsoever.
>
> The real issue was first seen on RT which at the time effectively always
> set the low_latency flag for all serial drivers by patching
> tty_flip_buffer_push(). This in turn revealed that many drivers did not
> handle the infamous low_latency behaviour which meant that data was
> pushed immediately to the line discipline instead of being deferred to a
> work queue.
>
> Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
> tty_flip_buffer_push() always schedules a work item to push data to the
> line discipline and there's no need to keep any low_latency hacks
> around.
>
> Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
> Cc: Tobias Klauser <tklauser@distanz.ch>
> Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Thanks
next prev parent reply other threads:[~2021-04-21 10:11 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 9:54 [PATCH 00/26] tty: drop low-latency workarounds Johan Hovold
2021-04-21 9:54 ` [PATCH 01/26] tty: mxser: drop low-latency workaround Johan Hovold
2021-04-22 5:59 ` Jiri Slaby
2021-04-21 9:54 ` [PATCH 02/26] serial: altera_jtaguart: " Johan Hovold
2021-04-21 10:03 ` Tobias Klauser [this message]
2021-04-21 9:54 ` [PATCH 03/26] serial: altera_uart: " Johan Hovold
2021-04-21 10:03 ` Tobias Klauser
2021-04-21 9:54 ` [PATCH 04/26] serial: amba-pl010: " Johan Hovold
2021-04-21 9:54 ` [PATCH 05/26] serial: amba-pl011: " Johan Hovold
2021-04-22 0:18 ` Linus Walleij
2021-04-21 9:54 ` [PATCH 06/26] serial: apbuart: " Johan Hovold
2021-04-21 9:54 ` [PATCH 07/26] serial: ar933x: " Johan Hovold
2021-04-21 9:54 ` [PATCH 08/26] serial: arc_uart: " Johan Hovold
2021-04-21 9:54 ` [PATCH 09/26] serial: atmel_serial: " Johan Hovold
2021-04-21 9:54 ` [PATCH 10/26] serial: bcm63xx: " Johan Hovold
2021-04-21 9:54 ` [PATCH 11/26] serial: icom: " Johan Hovold
2021-04-21 9:54 ` [PATCH 12/26] serial: lpc32xx_hs: " Johan Hovold
2021-04-21 9:54 ` [PATCH 13/26] serial: mcf: " Johan Hovold
2021-04-21 9:54 ` [PATCH 14/26] serial: meson: " Johan Hovold
2021-04-21 9:54 ` [PATCH 15/26] serial: mpc52xx_uart: " Johan Hovold
2021-04-21 9:54 ` [PATCH 16/26] serial: msm_serial: " Johan Hovold
2021-04-21 17:44 ` Bjorn Andersson
2021-04-21 9:55 ` [PATCH 17/26] serial: owl: " Johan Hovold
2021-04-21 9:55 ` [PATCH 18/26] serial: rda: " Johan Hovold
2021-04-21 9:55 ` [PATCH 19/26] serial: rp2: " Johan Hovold
2021-04-21 9:55 ` [PATCH 20/26] serial: sa1100: " Johan Hovold
2021-04-21 9:55 ` [PATCH 21/26] serial: txx9: " Johan Hovold
2021-04-21 9:55 ` [PATCH 22/26] serial: sifive: " Johan Hovold
2021-04-21 9:55 ` [PATCH 23/26] serial: sunsu: " Johan Hovold
2021-04-21 16:56 ` David Miller
2021-04-21 9:55 ` [PATCH 24/26] serial: timbuart: " Johan Hovold
2021-04-21 9:55 ` [PATCH 25/26] serial: vt8500: " Johan Hovold
2021-04-21 9:55 ` [PATCH 26/26] serial: xilinx_uartps: " Johan Hovold
2021-04-22 10:09 ` [PATCH 00/26] tty: drop low-latency workarounds Greg Kroah-Hartman
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