From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3DE1F349CC2; Wed, 1 Jul 2026 20:42:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782938571; cv=none; b=GgEKFlTweExKkHRCfQGTrhj2wwzMGp+54KBKhDA7cHm3QW2qBllvH97L7Ul2Gyu3m6SvDhK5472e9WiNKMSgDH8mYCwClaluP+lckY3Uu6TlfDG7OY3l1w04ZBbupLLutvPmonWTHis5fjb202BoiQFZ83pL3kcBYdw+EKYlJ6g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782938571; c=relaxed/simple; bh=urKLDAIiFmKybLLi6yfD2LKhWVS2RzdByI5RSDlIzQE=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Kjbcj3BU8TECKH5OhQqa/PW/itx1LFJCkZB72DfQaq/MSb3rhXezfaNs46iYKnM8oUqZFoQZWhG6xuJ5NzCQcMZpUv14o2kbtX3mFzSJh+j/PR/3rDvANHcZKLgdNFgr0XkmR4hCAOFzhN0sOzbpZsPSjxAzj1rMrKZBsoX9AZI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Q3UNtXuy; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Q3UNtXuy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5AD11F000E9; Wed, 1 Jul 2026 20:42:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782938569; bh=y1BvtaSNIJnoBgAy+XG9PF2qiaRpH3VVwPbPhFni4UA=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=Q3UNtXuyhh19YJ5CdkMbps5+pZGhxVz58KgyDNYf3gIfZ+MjzyWrXIquW7G0MOwSY 0QRWBusxxDkmYMb9s74F+Q78j6j/N60TLaXEKsChd2WFRgIFoQKqCtzrBQwqiIu1Jn UlgAiAOq+ONOEIqx0F5Y9ykfzdESSfh9icwpzQbL4V4Hdt1QX+lHQ9aiRfcJS9VrdP B6TgOF8AO9CakLES5w4nM0VzeSRsX7bZALSvGlJJvwmtW46298sltyeAzEUQ2ZlgfS 6YZ/A8VhCYFTzCI9TQ0f4ZSNFXIasr3sWGWrzF6oW9QUFXFr1NqKJzWYjcp2aRCetM adcIc9FGirCkg== Date: Wed, 1 Jul 2026 21:42:44 +0100 From: Jonathan Cameron To: Batu Ada Tutkun Cc: David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , Greg Kroah-Hartman , linux-iio@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] staging: iio: frequency: ad9834: use guard() for mutex locking Message-ID: <20260701214244.11dc26f7@jic23-huawei> In-Reply-To: <20260625120456.1267-1-batuadatutkun@gmail.com> References: <20260625120456.1267-1-batuadatutkun@gmail.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 25 Jun 2026 15:04:55 +0300 Batu Ada Tutkun wrote: > Replace manual mutex_lock()/mutex_unlock() pairs with guard(mutex) in > ad9834_write() and ad9834_store_wavetype(). The mutex is now released > automatically when each function returns, removing the need for > explicit unlock calls. > > Signed-off-by: Batu Ada Tutkun Whilst we aren't taking this forwards, a few comments inline for future reference. > --- > drivers/staging/iio/frequency/ad9834.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c > index bdb2580e2..f15819eaf 100644 > --- a/drivers/staging/iio/frequency/ad9834.c > +++ b/drivers/staging/iio/frequency/ad9834.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include I'm guessing cleanup.h is missing as well. You should have both when guard(mutex) is is in use. > #include > > #include > @@ -152,7 +153,7 @@ static ssize_t ad9834_write(struct device *dev, > if (ret) > return ret; > > - mutex_lock(&st->lock); > + guard(mutex)(&st->lock); > switch ((u32)this_attr->address) { > case AD9834_REG_FREQ0: > case AD9834_REG_FREQ1: > @@ -210,7 +211,6 @@ static ssize_t ad9834_write(struct device *dev, > default: > ret = -ENODEV; The big advantage of using guard() is not removing mutex_unlock() but instead that you can use simpler code flow. Here you should return early. There are a lot of error returns in this function and it may even make sense to return len early if no error. > } > - mutex_unlock(&st->lock); > > return ret ? ret : len; > } > @@ -226,7 +226,7 @@ static ssize_t ad9834_store_wavetype(struct device *dev, > int ret = 0; > bool is_ad9833_7 = (st->devid == ID_AD9833) || (st->devid == ID_AD9837); > > - mutex_lock(&st->lock); > + guard(mutex)(&st->lock); > > switch ((u32)this_attr->address) { > case 0: > @@ -269,7 +269,6 @@ static ssize_t ad9834_store_wavetype(struct device *dev, > st->data = cpu_to_be16(AD9834_REG_CMD | st->control); > ret = spi_sync(st->spi, &st->msg); > } > - mutex_unlock(&st->lock); Similar applies in this function where there are a lot of paths that can become early error returns if guard() is used. Jonathan > > return ret ? ret : len; > }