From: Jarkko Sonninen <kasper@iki.fi>
To: Oliver Neukum <oneukum@suse.com>
Cc: Johan Hovold <johan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] USB: serial: xr: Add TIOCGRS485 and TIOCSRS485 ioctls
Date: Mon, 13 Mar 2023 12:47:17 +0200 [thread overview]
Message-ID: <3c53eca1-ce62-e98d-ee52-269a09480658@iki.fi> (raw)
In-Reply-To: <e426ae4c-4e49-5773-e8da-919fa2e3dc33@suse.com>
Hello,
It uses only one flag from the struct from user. Would it be better to
store only that to state ?
Do I need locking at all in that case ?
The whole struct is stored just in case, if someone would implement
other functionality later.
- Jarkko
Oliver Neukum kirjoitti 13/03/2023 klo 11.54:
>
>
> On 13.03.23 09:27, Jarkko Sonninen wrote:
>> Add support for RS-485 in Exar USB adapters.
>> RS-485 mode is controlled by TIOCGRS485 and TIOCSRS485 ioctls.
>> Gpio mode register is set to enable RS-485.
>>
>> Signed-off-by: Jarkko Sonninen <kasper@iki.fi>
>
>
> Hi,
>
> I am sorry, but locking is really broken here. All these contexts can
> sleep.
> There is no need for a spinlock. As far as you need locking, just use
> a mutex.
>
> Secondly, if xr_set_rs485_config() needs locking, so will
> xr_get_rs485_config()
> or you can get the case that you return half a new and half an old
> state to user
> space.
>
> Regards
> Oliver
next prev parent reply other threads:[~2023-03-13 10:47 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-13 1:04 [PATCH] " Jarkko Sonninen
2023-03-13 7:00 ` Greg Kroah-Hartman
2023-03-13 7:49 ` Jarkko Sonninen
2023-03-13 7:53 ` Greg Kroah-Hartman
2023-03-13 8:27 ` [PATCH v2] " Jarkko Sonninen
2023-03-13 8:45 ` Greg Kroah-Hartman
2023-03-13 9:54 ` Oliver Neukum
2023-03-13 10:47 ` Jarkko Sonninen [this message]
2023-03-13 11:27 ` Oliver Neukum
2023-03-13 23:02 ` David Laight
2023-03-14 6:19 ` kernel test robot
2023-03-13 15:07 ` [PATCH] " Jarkko Sonninen
2023-03-13 15:50 ` Greg Kroah-Hartman
2023-03-13 15:53 ` Jarkko Sonninen
2023-03-13 20:18 ` Oliver Neukum
2023-03-14 7:00 ` [PATCH v3] " Jarkko Sonninen
2023-03-14 7:37 ` Greg Kroah-Hartman
2023-03-14 8:00 ` Jarkko Sonninen
2023-04-13 8:57 ` Johan Hovold
2023-04-13 8:53 ` Johan Hovold
2023-04-16 8:40 ` Jarkko Sonninen
2023-04-17 14:50 ` Johan Hovold
2023-04-23 18:59 ` [PATCH v4] " Jarkko Sonninen
2023-04-24 5:32 ` kernel test robot
2023-06-20 12:38 ` Johan Hovold
2023-07-06 19:37 ` Jarkko Sonninen
2023-07-20 13:46 ` Johan Hovold
2023-07-08 14:56 ` [PATCH v5] " Jarkko Sonninen
2023-07-20 13:52 ` Johan Hovold
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