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Darwish" , linux-omap@vger.kernel.org, Shuah Khan , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org keyspan_pda_write() uses in_interrupt() to check whether it is safe to invoke functions which might sleep. 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 seperated or the context be conveyed in an argument passed by the caller, which usually knows the context. Aside of that it does not cover all contexts which cannot sleep, e.g. preempt disabled regions which cannot be reliably detected on all kernel configurations. With the current printk() implementation console->write() can be invoked from almost any context. The upcoming rework of the console core will provide thread context for console drivers which require to sleep. For now, restrict the room query which can sleep to tty writes which happen from preemptible task context. The usability for dmesg output is limited anyway because it's almost guaranteed to drop the 'LF' which is submitted after the dmesg line because the device supports only one transfer on flight. Same for any printk() which is coming in before the previous transfer has been done. This new restriction does not make it worse than before, but it makes the condition correct under all circumstances. Signed-off-by: Ahmed S. Darwish Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Cc: Johan Hovold Cc: Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org --- drivers/usb/serial/keyspan_pda.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/drivers/usb/serial/keyspan_pda.c +++ b/drivers/usb/serial/keyspan_pda.c @@ -477,10 +477,12 @@ static int keyspan_pda_write(struct tty_ count = (count > port->bulk_out_size) ? port->bulk_out_size : count; - /* Check if we might overrun the Tx buffer. If so, ask the - device how much room it really has. This is done only on - scheduler time, since usb_control_msg() sleeps. */ - if (count > priv->tx_room && !in_interrupt()) { + /* + * Check if we might overrun the Tx buffer. If so, ask the device + * how much room it really has. This can only be invoked for tty + * usage because the console write can't sleep. + */ + if (count > priv->tx_room && tty) { u8 *room; room = kmalloc(1, GFP_KERNEL); _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel