Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752394AbdGEHhf (ORCPT ); Wed, 5 Jul 2017 03:37:35 -0400 Received: from 92-243-34-74.adsl.nanet.at ([92.243.34.74]:33092 "EHLO mail.osadl.at" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751604AbdGEHhe (ORCPT ); Wed, 5 Jul 2017 03:37:34 -0400 Date: Wed, 5 Jul 2017 07:37:05 +0000 From: Nicholas Mc Guire To: Jonathan Cameron Cc: Geert Uytterhoeven , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , simran singhal , Arnd Bergmann , Gregor Boirie , linux-iio@vger.kernel.org, "linux-kernel@vger.kernel.org" Subject: Re: [PATCH RFC] iio: pressure: zpa2326: report interrupted case as failure Message-ID: <20170705073705.GA8145@osadl.at> References: <1494751435-14189-1-git-send-email-der.herr@hofr.at> <20170704200853.16dc9e3a@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170704200853.16dc9e3a@kernel.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3687 Lines: 92 On Tue, Jul 04, 2017 at 08:08:53PM +0100, Jonathan Cameron wrote: > On Tue, 4 Jul 2017 12:40:33 +0200 > Geert Uytterhoeven wrote: > > > Hi Nicholas, > > > > On Sun, May 14, 2017 at 10:43 AM, Nicholas Mc Guire wrote: > > > If the timeout-case prints a warning message then probably the interrupted > > > case should also. Further, wait_for_completion_interruptible_timeout() > > > returns long not int. > > > > > > Fixes: commit 03b262f2bbf4 ("iio:pressure: initial zpa2326 barometer support") > > > Signed-off-by: Nicholas Mc Guire > > > --- > > > > > > The original control-flow was technically not wrong just confusing and a bit > > > complicated. Not clear if reporting the interrupted case actually is useful, > > > but given that the timeout is relatively long (200ms) it is not that unlikely > > > so differentiating the cases seems helpful. > > > > > > Patch was compile-tested with: x86_64_defconfig + CONFIG_IIO=m, CONFIG_ZPA2326=m > > > > > > Patch is against v4.11 (localversion-next is next-20170512) > > > > > > drivers/iio/pressure/zpa2326.c | 17 ++++++++++------- > > > 1 file changed, 10 insertions(+), 7 deletions(-) > > > > > > diff --git a/drivers/iio/pressure/zpa2326.c b/drivers/iio/pressure/zpa2326.c > > > index e58a0ad..617926f 100644 > > > --- a/drivers/iio/pressure/zpa2326.c > > > +++ b/drivers/iio/pressure/zpa2326.c > > > @@ -867,12 +867,13 @@ static int zpa2326_wait_oneshot_completion(const struct iio_dev *indio_dev, > > > { > > > int ret; > > > unsigned int val; > > > + long timeout; > > > > > > zpa2326_dbg(indio_dev, "waiting for one shot completion interrupt"); > > > > > > - ret = wait_for_completion_interruptible_timeout( > > > + timeout = wait_for_completion_interruptible_timeout( > > > &private->data_ready, ZPA2326_CONVERSION_JIFFIES); > > > - if (ret > 0) > > > + if (timeout > 0) > > > > Check for strict positive timeout. > > > > > /* > > > * Interrupt handler completed before timeout: return operation > > > * status. > > > @@ -882,13 +883,15 @@ static int zpa2326_wait_oneshot_completion(const struct iio_dev *indio_dev, > > > /* Clear all interrupts just to be sure. */ > > > regmap_read(private->regmap, ZPA2326_INT_SOURCE_REG, &val); > > > > > > - if (!ret) > > > + if (!timeout) { > > > > Check for zero timeout. > > > > > /* Timed out. */ > > > + zpa2326_warn(indio_dev, "no one shot interrupt occurred (%ld)", > > > + timeout); > > > ret = -ETIME; > > > - > > > - if (ret != -ERESTARTSYS) > > > - zpa2326_warn(indio_dev, "no one shot interrupt occurred (%d)", > > > - ret); > > > + } else if (timeout < 0) { > > > > So if we get here, timeout is always strict negative, so the check can > > be removed. > > > > > + zpa2326_warn(indio_dev, "wait for one shot interrupt canceled"); > > > + ret = -ERESTARTSYS; > > > + } > > > > > > return ret; > > > > But gcc-4.1.2 is not smart enough: > > > > drivers/iio/pressure/zpa2326.c:868: warning: ???ret??? may be used > > uninitialized in this function > Good analysis. Care to send the obvious patch? > Thanks Geert for finding that - yes ret needs to be initialized to 0 here, success case as documented in the header of zpa2326_wait_oneshot_completion - interestingly enough gcc gcc (Debian 4.9.2-10) 4.9.2 does not flag this uninitioalized variable ! thx! hofrat