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From: Greg KH <gregkh@linuxfoundation.org>
To: Zheyu Ma <zheyuma97@gmail.com>
Cc: cernekee@gmail.com, jirislaby@kernel.org,
	linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] serial: rp2: use 'request_firmware' instead of 'request_firmware_nowait'
Date: Fri, 21 May 2021 08:51:16 +0200	[thread overview]
Message-ID: <YKdYZF8zDGl0hxeX@kroah.com> (raw)
In-Reply-To: <1621577323-1541-1-git-send-email-zheyuma97@gmail.com>

On Fri, May 21, 2021 at 06:08:43AM +0000, Zheyu Ma wrote:
> In 'rp2_probe', the driver registers 'rp2_uart_interrupt' then calls
> 'rp2_fw_cb' through 'request_firmware_nowait'. In 'rp2_fw_cb', if the
> firmware don't exists, function just return without initializing ports
> of 'rp2_card'. But now the interrupt handler function has been
> registered, and when an interrupt comes, 'rp2_uart_interrupt' may access
> those ports then causing NULL pointer dereference or other bugs.
> 
> Because the driver does some initialization work in 'rp2_fw_cb', in
> order to make the driver ready to handle interrupts, 'request_firmware'
> should be used instead of asynchronous 'request_firmware_nowait'.

You just now slowed down the probe function.  Are you _sure_ this is ok?

Do you have this hardware to test this?  If so, what is the init time
before and after this change?

thanks,

greg k-h

  reply	other threads:[~2021-05-21  6:51 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-21  6:08 [PATCH v2] serial: rp2: use 'request_firmware' instead of 'request_firmware_nowait' Zheyu Ma
2021-05-21  6:51 ` Greg KH [this message]
2021-05-21 11:15   ` Zheyu Ma
2021-05-21 11:31     ` Greg KH

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