From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754353AbeCROuB (ORCPT ); Sun, 18 Mar 2018 10:50:01 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:41772 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754176AbeCROt5 (ORCPT ); Sun, 18 Mar 2018 10:49:57 -0400 X-Google-Smtp-Source: AG47ELtOpTJMRxRJp1Lgy2xTT2ljknldKPKXJww5xWuI3kkhsu4ijJ0lBZswHYmxiT6vBPhn2olkpw== From: Jia-Ju Bai To: laforge@gnumonks.org Cc: linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: [PATCH] char: pcmcia: cm4000_cs: Replace mdelay with usleep_range in set_protocol Date: Sun, 18 Mar 2018 22:49:57 +0800 Message-Id: <1521384597-23195-1-git-send-email-baijiaju1990@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org set_protocol() is never called in atomic context. The call chains ending up at set_protocol() are: [1] set_protocol() <- monitor_card() [2] set_protocol() <- cmm_ioctl() monitor_card() is only set in setup_timer(), and cmm_ioctl() is only set as ".unlocked_ioctl" in file_operations structure "cm4000_fops". Despite never getting called from atomic context, set_protocol() calls mdelay(10), i.e. busy wait for 10ms. That is not necessary and can be replaced with usleep_range to avoid busy waiting. This is found by a static analysis tool named DCNS written by myself. Signed-off-by: Jia-Ju Bai --- drivers/char/pcmcia/cm4000_cs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/char/pcmcia/cm4000_cs.c b/drivers/char/pcmcia/cm4000_cs.c index cd53771..56fc671 100644 --- a/drivers/char/pcmcia/cm4000_cs.c +++ b/drivers/char/pcmcia/cm4000_cs.c @@ -530,7 +530,7 @@ static int set_protocol(struct cm4000_dev *dev, struct ptsreq *ptsreq) DEBUGP(5, dev, "NumRecBytes is valid\n"); break; } - mdelay(10); + usleep_range(10000, 11000); } if (i == 100) { DEBUGP(5, dev, "Timeout waiting for NumRecBytes getting " @@ -546,7 +546,7 @@ static int set_protocol(struct cm4000_dev *dev, struct ptsreq *ptsreq) DEBUGP(2, dev, "NumRecBytes = %i\n", num_bytes_read); break; } - mdelay(10); + usleep_range(10000, 11000); } /* check whether it is a short PTS reply? */ -- 1.9.1