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Fri, 3 Feb 2023 19:55:31 -0500 (EST) Date: Sat, 4 Feb 2023 09:55:27 +0900 From: Takashi Sakamoto To: Takashi Iwai Subject: Re: [PATCH] ALSA: fireface: add field for the number of messages copied to user space Message-ID: Mail-Followup-To: Takashi Iwai , alsa-devel@alsa-project.org References: <20230202133708.163936-1-o-takashi@sakamocchi.jp> <87fsbmn2gf.wl-tiwai@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87fsbmn2gf.wl-tiwai@suse.de> X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alsa-devel@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" Hi, On Fri, Feb 03, 2023 at 05:22:40PM +0100, Takashi Iwai wrote: > On Thu, 02 Feb 2023 14:37:08 +0100, > Takashi Sakamoto wrote: > > > > Current structure includes no field to express the number of messages > > copied to user space, thus user space application needs to information > > out of the structure to parse the content of structure. > > > > This commit adds a field to express the number of messages copied to user > > space since It is more preferable to use self-contained structure. > > > > Kees Cook proposed an idea of annotation for bound of flexible arrays > > in his future improvement for flexible-length array in kernel. The > > additional field for message count is suitable to the idea as well. > > > > Reference: https://people.kernel.org/kees/bounded-flexible-arrays-in-c > > Signed-off-by: Takashi Sakamoto > > Wouldn't changing this break the existing application that talks with > the older ABI? Just to be sure... You may well have the concern, indeed. The structure is not exposed to user space yet, since it was added by a commit ab811cfffa9 ("ALSA: fireface: update UAPI for data of knob control"). It just exists in your (and mine) tree at present. Thanks Takashi Sakamoto