From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 4946A382; Tue, 1 Jul 2025 19:29:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751398197; cv=none; b=VAiuE5CH+IBt/8pPgOW8oX4aiGebxmH3qF0HajyxOVhIyev+9627M+Sf+MnzrZG5uWVAnQUtLrfGvVJe3CAkf8ns61Lg4Uhyb9+Za1Yb8t8kNUAk3l2ZcFsE1++sG2Oz4h6L0IDvPtj6zv6udHsx9POK6kc3G+GtNywU//eFz8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751398197; c=relaxed/simple; bh=UeQXokiUpfIRKzCV4siHL91mgA1HxJxuNduWOJ0cc/A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ct5CiTOe//1QSOgPtbGkw3qcWjltLphjnLRvZ7c/zjMvIkfCtrDjMvxJjHz86vY+43q5HCF0XKW6MtlRXj7syb8Z1BK3airmpr+2VylytZXlX8PqcAvypCKu1LhjNOLBQZ7lXOSVs3n8gqYgmtWsYLEcL1cp/fhvtLIMnDH3QWI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=LQ9IBkJ9; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="LQ9IBkJ9" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id D5B04778; Tue, 1 Jul 2025 21:29:31 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1751398172; bh=UeQXokiUpfIRKzCV4siHL91mgA1HxJxuNduWOJ0cc/A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LQ9IBkJ9E0I0v8VB4ePqnqGQXO8B6MacZ/vgwdwg/GXmzybL/r52BD0gYWBXAS4er cKvwJsS5e3KuHLR6Znb/VAKxSi+UeCOruuiBrFm5zClONa+rSKsXTG9UYJAtF5zIXQ Wcd87Cr5Qn5C5mKsXIvPOjN9OPBs2jKUXym2txSc= Date: Tue, 1 Jul 2025 22:29:28 +0300 From: Laurent Pinchart To: Ricardo Ribalda Cc: Desnes Nunes , hansg@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] media: uvcvideo: avoid variable shadowing in uvc_ctrl_cleanup_fh Message-ID: <20250701192928.GB16835@pendragon.ideasonboard.com> References: <20250701145240.105959-1-desnesn@redhat.com> <20250701184134.GC1936@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Jul 01, 2025 at 09:25:59PM +0200, Ricardo Ribalda wrote: > On Tue, 1 Jul 2025 at 20:42, Laurent Pinchart > wrote: > > > > On Tue, Jul 01, 2025 at 02:20:53PM -0300, Desnes Nunes wrote: > > > On Tue, Jul 1, 2025 at 1:48 PM Ricardo Ribalda wrote: > > > > On Tue, 1 Jul 2025 at 16:59, Desnes Nunes wrote: > > > > > > > > > > This avoids a variable loop shadowing occurring between the local loop > > > > > iterating through the uvc_entity's controls and the global one going > > > > > through the pending async controls of the file handle > > > > > > > > > > Fixes: 10acb9101355 ("media: uvcvideo: Increase/decrease the PM counter per IOCTL") > > > > If you add a fixes you need to add > > > > Cc: stable@kernel.org > > > > > > Thanks for letting me know > > > > > > > Reviewed-by: Ricardo Ribalda > > > > > Signed-off-by: Desnes Nunes > > > > > --- > > > > > drivers/media/usb/uvc/uvc_ctrl.c | 3 +-- > > > > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > > > > > index 44b6513c5264..91cc874da798 100644 > > > > > --- a/drivers/media/usb/uvc/uvc_ctrl.c > > > > > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > > > > > @@ -3260,7 +3260,6 @@ int uvc_ctrl_init_device(struct uvc_device *dev) > > > > > void uvc_ctrl_cleanup_fh(struct uvc_fh *handle) > > > > > { > > > > > struct uvc_entity *entity; > > > > > - int i; > > > > > > > > > > guard(mutex)(&handle->chain->ctrl_mutex); > > > > > > > > > > @@ -3278,7 +3277,7 @@ void uvc_ctrl_cleanup_fh(struct uvc_fh *handle) > > > > > if (!WARN_ON(handle->pending_async_ctrls)) > > > > > return; > > > > > > > > > > - for (i = 0; i < handle->pending_async_ctrls; i++) > > > > > > > > nitpick: I would have called the variable i, not j. For me j usually > > > > means nested loop. But up to you > > > > > > Noted - I used a different variable name because I wanted to > > > differentiate the loops. > > > > Variable declaration in the loop statement is relatively new in the > > kernel, so there's no consensus yet (to my knowledge) on clear coding > > styles, but I would have simply used the same variable name in both > > loops, with two separate declarations: > > > > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c > > index 303b7509ec47..6b9486749c3f 100644 > > --- a/drivers/media/usb/uvc/uvc_ctrl.c > > +++ b/drivers/media/usb/uvc/uvc_ctrl.c > > @@ -3299,7 +3299,6 @@ int uvc_ctrl_init_device(struct uvc_device *dev) > > void uvc_ctrl_cleanup_fh(struct uvc_fh *handle) > > { > > struct uvc_entity *entity; > > - int i; > > > > guard(mutex)(&handle->chain->ctrl_mutex); > > > > @@ -3317,7 +3316,7 @@ void uvc_ctrl_cleanup_fh(struct uvc_fh *handle) > > if (!WARN_ON(handle->pending_async_ctrls)) > > return; > > > > - for (i = 0; i < handle->pending_async_ctrls; i++) > > + for (unsigned int i = 0; i < handle->pending_async_ctrls; i++) > > uvc_pm_put(handle->stream->dev); > > } > > > > Is there a downside to this ? > > The toolchain that they are using does not seem to like it, Well, this is mainline :-) > and there > is no benefit for having two initialization vs one. > > (also makes the lines shorter... but that is just a matter of taste). > > I don't really have a preference. Declaring the variable in the loop statement removes the possibility of using it outside of the loop. I think that's an improvement in general, it makes reading the code simpler, and avoids accidental misuse. > > > > I am also not against your first version with a different commit message. > > > > > > Third time's a charm then! > > > > > > Will send a v2 with the first version having this commit message. > > > > > > Thanks for the review Ricardo, -- Regards, Laurent Pinchart