Re: [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage
From: Johan Hovold <johan@kernel.org>
Date: 2020-10-25 17:16:16
Also in:
linux-omap, linux-samsung-soc, linux-usb, lkml
On Mon, Oct 19, 2020 at 12:06:33PM +0200, Thomas Gleixner wrote:
From: Ahmed S. Darwish <redacted> 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. ;)
quoted hunk ↗ jump to hunk
Remove the in_interrupt() printout and make the printk() depend on tty. Signed-off-by: Ahmed S. Darwish <redacted> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <redacted> 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);
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