From: Johan Hovold <johan@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"Ahmed S. Darwish" <a.darwish@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Johan Hovold <johan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org,
Thomas Winischhofer <thomas@winischhofer.net>,
Mathias Nyman <mathias.nyman@intel.com>,
Valentina Manea <valentina.manea.m@gmail.com>,
Shuah Khan <shuah@kernel.org>,
Alan Stern <stern@rowland.harvard.edu>,
linux-omap@vger.kernel.org, Kukjin Kim <kgene@kernel.org>,
Krzysztof Kozlowski <krzk@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org,
Felipe Balbi <balbi@kernel.org>,
Duncan Sands <duncan.sands@free.fr>
Subject: Re: [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage
Date: Sun, 25 Oct 2020 18:16:13 +0100 [thread overview]
Message-ID: <20201025171613.GT26280@localhost> (raw)
In-Reply-To: <20201019101110.019266389@linutronix.de>
On Mon, Oct 19, 2020 at 12:06:33PM +0200, Thomas Gleixner wrote:
> From: Ahmed S. Darwish <a.darwish@linutronix.de>
>
> The usage of in_interrupt() in drivers is phased out and Linus clearly
> requested that code which changes behaviour depending on context should
> either be separated or the context be conveyed in an argument passed by the
> caller, which usually knows the context.
>
> The debug printk() in digi_write() prints in_interrupt() as context
> information. TTY writes happen always in preemptible task context and
> console writes can happen from almost any context, so in_interrupt() is not
> really helpful.
The above statement is not correct, TTY writes can and do happen from
other contexts, including soft IRQ (e.g. PPP).
> Aside of that issuing a printk() from a console->write() callback is not a
> really brilliant idea for obvious reasons.
True, but we don't need to sprinkle conditionals for the benefit of
people trying to debug USB serial drivers using a USB serial console.
They get what they deserve. ;)
> Remove the in_interrupt() printout and make the printk() depend on tty.
>
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
>
> ---
> drivers/usb/serial/digi_acceleport.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> --- a/drivers/usb/serial/digi_acceleport.c
> +++ b/drivers/usb/serial/digi_acceleport.c
> @@ -911,9 +911,10 @@ static int digi_write(struct tty_struct
> unsigned char *data = port->write_urb->transfer_buffer;
> unsigned long flags = 0;
>
> - dev_dbg(&port->dev,
> - "digi_write: TOP: port=%d, count=%d, in_interrupt=%ld\n",
> - priv->dp_port_num, count, in_interrupt());
> + if (tty) {
> + dev_dbg(&port->dev, "digi_write: TOP: port=%d, count=%d\n",
> + priv->dp_port_num, count);
> + }
So just drop the in_interrupt() here.
Also note that we already have another unconditional dev_dbg() at the
end of this function.
>
> /* copy user data (which can sleep) before getting spin lock */
> count = min(count, port->bulk_out_size-2);
>
Johan
next prev parent reply other threads:[~2020-10-25 17:16 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
2020-10-19 10:06 ` [patch V2 01/13] USB: sisusbvga: Make console support depend on BROKEN Thomas Gleixner
2020-10-19 10:06 ` [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage Thomas Gleixner
2020-10-25 16:56 ` Johan Hovold
2020-10-26 12:47 ` Sebastian Andrzej Siewior
2020-10-27 8:16 ` Johan Hovold
2020-10-19 10:06 ` [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query Thomas Gleixner
2020-10-25 17:05 ` Johan Hovold
2020-10-19 10:06 ` [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage Thomas Gleixner
2020-10-25 17:16 ` Johan Hovold [this message]
2020-10-26 14:03 ` [PATCH v3 04/13 ] " Sebastian Andrzej Siewior
2020-10-27 8:26 ` Johan Hovold
2020-10-19 10:06 ` [patch V2 05/13] usb: xhci: Remove in_interrupt() checks Thomas Gleixner
2020-10-19 10:06 ` [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage Thomas Gleixner
2020-10-28 11:27 ` Greg Kroah-Hartman
2020-10-19 10:06 ` [patch V2 07/13] usbip: Remove in_interrupt() check Thomas Gleixner
2020-10-19 10:06 ` [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments Thomas Gleixner
2020-10-19 16:28 ` Alan Stern
2020-10-19 10:06 ` [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove() Thomas Gleixner
2020-10-19 16:28 ` Alan Stern
2020-10-19 10:06 ` [patch V2 10/13] usb: gadget: pxa27x_udc: Replace in_interrupt() usage in comments Thomas Gleixner
2020-10-19 10:06 ` [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments Thomas Gleixner
2020-10-19 16:28 ` Alan Stern
2020-10-19 10:06 ` [patch V2 12/13] usb: core: Replace in_interrupt() in comments Thomas Gleixner
2020-10-19 16:28 ` Alan Stern
2020-10-19 10:06 ` [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment Thomas Gleixner
2020-10-19 10:28 ` Duncan Sands
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