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 3C20B83A07; Thu, 4 Apr 2024 13:00:36 +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=1712235637; cv=none; b=j2KpyKBtkIHtawNBfW5mIHyR3aO+jmpJr+UUA/+WWexzF4Xq7bRHTzABqrbwtSR1CrdQSW4OARD6Xf2QLxTIW87H5ivT16yM2yFiv+CzwcGX/ZVrlX9oyEzb7Uy7GVxEtxO6VspzeEMbnUQqoTqXpvc+5B7xQ7CkUgjbZ3/s0eY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712235637; c=relaxed/simple; bh=FIKEWYk5qVyb6MFcCcB7Ld4kq8WkA50kchpgcd7X3Io=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QpOGPBS2m2CeziGbmySFbOnzv2QdBaviaAvkOV+eOAVKjx+Ql3x7ypcogdttjEjWRIfIDuNJv3IPIGjcG+gfTu7NpU33bT0tLAVpKcZ5FjMF1oRxDLC0x3WQVI+IU+cQX88Ly7U7p+bS6pqf0KWyjOa0ZOIrS8TxCX6NqvOxf4g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=VhVeIhLu; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="VhVeIhLu" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 01B7912D; Thu, 4 Apr 2024 14:59:55 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1712235596; bh=FIKEWYk5qVyb6MFcCcB7Ld4kq8WkA50kchpgcd7X3Io=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VhVeIhLuGxkwFBKk1TVap7G/4Tv849PjsnhKDmv6Gurso8nN9Kx/WtQVPwaf5ScTz Vvs/iH/S5j9q79VPrGj3VgpFrodBkuUUFl5IifajwrhJLOK3T/vwcEQTVXA1Pgo7ld p742aKgK5D3wtENG5RzSR4mGgzUcdb8NYM0Kupfc= Date: Thu, 4 Apr 2024 16:00:22 +0300 From: Laurent Pinchart To: Tomi Valkeinen Cc: Mauro Carvalho Chehab , Hans Verkuil , Sakari Ailus , Umang Jain , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] media: subdev: Fix use of sd->enabled_streams in call_s_stream() Message-ID: <20240404130022.GQ23803@pendragon.ideasonboard.com> References: <20240404-enable-streams-impro-v1-0-1017a35bbe07@ideasonboard.com> <20240404-enable-streams-impro-v1-2-1017a35bbe07@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 In-Reply-To: <20240404-enable-streams-impro-v1-2-1017a35bbe07@ideasonboard.com> Hi Tomi, Thank you for the patch. On Thu, Apr 04, 2024 at 01:50:01PM +0300, Tomi Valkeinen wrote: > call_s_stream() uses sd->enabled_streams to track whether streaming has > already been enabled. However, > v4l2_subdev_enable/disable_streams_fallback(), which was the original > user of this field, already uses it, and > v4l2_subdev_enable/disable_streams_fallback() will call call_s_stream(). > > This leads to a conflict as both functions set the field. Afaics, both > functions set the field to the same value, so it won't cause a runtime > bug, but it's still wrong and if we, e.g., change how > v4l2_subdev_enable/disable_streams_fallback() operates we might easily > cause bugs. > > Fix this by adding a new field, 'streaming_enabled', for > call_s_stream(). > > Signed-off-by: Tomi Valkeinen > --- > drivers/media/v4l2-core/v4l2-subdev.c | 8 ++------ > include/media/v4l2-subdev.h | 2 ++ > 2 files changed, 4 insertions(+), 6 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > index b90b5185e87f..3b3310bce5d4 100644 > --- a/drivers/media/v4l2-core/v4l2-subdev.c > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > @@ -404,12 +404,8 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable) > * The .s_stream() operation must never be called to start or stop an > * already started or stopped subdev. Catch offenders but don't return > * an error yet to avoid regressions. > - * > - * As .s_stream() is mutually exclusive with the .enable_streams() and > - * .disable_streams() operation, we can use the enabled_streams field > - * to store the subdev streaming state. > */ > - if (WARN_ON(!!sd->enabled_streams == !!enable)) > + if (WARN_ON(!!sd->streaming_enabled == !!enable)) > return 0; > > #if IS_REACHABLE(CONFIG_LEDS_CLASS) > @@ -429,7 +425,7 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable) > } > > if (!ret) > - sd->enabled_streams = enable ? BIT(0) : 0; > + sd->streaming_enabled = !!enable; > > return ret; > } > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h > index a9e6b8146279..8bd1e3c96d2b 100644 > --- a/include/media/v4l2-subdev.h > +++ b/include/media/v4l2-subdev.h > @@ -1043,6 +1043,7 @@ struct v4l2_subdev_platform_data { > * v4l2_subdev_enable_streams() and > * v4l2_subdev_disable_streams() helper functions for fallback > * cases. > + * @streaming_enabled: Tracks whether streaming has been enabled with s_stream. Could you extend this to indicate this field can't be used by anything else than call_s_stream() ? I'm also getting a bit concerned about having multiple fields with similar purposes. Another option would be to call the .s_stream() operation directly from the fallback handlers, instead of going through call_s_stream(). That may be considered as a bit of a hack though. > * > * Each instance of a subdev driver should create this struct, either > * stand-alone or embedded in a larger struct. > @@ -1091,6 +1092,7 @@ struct v4l2_subdev { > */ > struct v4l2_subdev_state *active_state; > u64 enabled_streams; > + bool streaming_enabled; > }; > > -- Regards, Laurent Pinchart