From patchwork Wed Oct 14 14:52:17 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 11837867 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 84FC11580 for ; Wed, 14 Oct 2020 15:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E04A2222A for ; Wed, 14 Oct 2020 15:18:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="k5Uvd0CH"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="OrT6mgTc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731742AbgJNPSw (ORCPT ); Wed, 14 Oct 2020 11:18:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731731AbgJNPSu (ORCPT ); Wed, 14 Oct 2020 11:18:50 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA3E2C0613D2; Wed, 14 Oct 2020 08:18:50 -0700 (PDT) Message-Id: <20201014145727.209520987@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1602688729; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=j+vN9MgqREoIPGzBU7B1IaC3gna3kE7EN539Nh0ClUU=; b=k5Uvd0CHm0zZyEwL+YuKNjNUOvaRu4R270eVkBILUGSOB7QRbX2osy1phwsfegSjghqyrW sJWQY5reBOT1yyFMi1bGeG5Wu6vT7FKqS1iRXgKFN/Ba6r4wc64mBYG0+gj36pE45eSlJY kNBxpmqbrmhYi6IiRdc3kOcf+pgTR92lCnMjReOKjdQ5w+fk/T7eTXOkzl+dLA6A3JUOyO GwZNF/9lRzATa+y3TN2kH5+JHJnIixp3tE3SMBjM2+Jy+eA9tnRQdLCKxXXXCeq4Pep7sl CHizp9HNv/SgRakHrfj+HJOkJlFablJugSEnDkzqqJkdfFLQI6t9kATI5TafEw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1602688729; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=j+vN9MgqREoIPGzBU7B1IaC3gna3kE7EN539Nh0ClUU=; b=OrT6mgTchqOnwodWRSOWnTUctuEN6qg/WU3nIlLDVaCTruOVTQIY5kwbMcQtZllOQS8XNQ DAfGWB0ldz/F46CA== Date: Wed, 14 Oct 2020 16:52:17 +0200 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , "Ahmed S. Darwish" , Sebastian Andrzej Siewior , Johan Hovold , Greg Kroah-Hartman , linux-usb@vger.kernel.org, Thomas Winischhofer , Mathias Nyman , Valentina Manea , Shuah Khan , Alan Stern , linux-omap@vger.kernel.org, Kukjin Kim , Krzysztof Kozlowski , linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, Felipe Balbi , Duncan Sands Subject: [patch 02/12] USB: serial: keyspan_pda: Replace in_interrupt() usage References: <20201014145215.518912759@linutronix.de> MIME-Version: 1.0 Content-transfer-encoding: 8-bit Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.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);