From patchwork Tue Mar 5 17:25:32 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Gustavo A. R. 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R. Silva" To: Takashi Sakamoto , Clemens Ladisch , Jaroslav Kysela , Takashi Iwai Cc: Kees Cook , linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org, alsa-devel@alsa-project.org, linux-sound@vger.kernel.org, linux1394-devel@lists.sourceforge.net Subject: [PATCH 2/2][next] ALSA: firewire-lib: Avoid -Wflex-array-member-not-at-end warning Message-ID: References: Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting ready to enable it globally. There is currently a local structure `template` that is using a flexible `struct fw_iso_packet` as a header for an on-stack array `__be32 header[CIP_HEADER_QUADLETS];`. struct { struct fw_iso_packet params; __be32 header[CIP_HEADER_QUADLETS]; } template = { {0}, {0} }; However, we are deprecating flexible arrays in the middle of another struct. So, in order to avoid this, we use the `struct_group_tagged()` helper to separate the flexible array from the rest of the members in the flexible structure: struct fw_iso_packet { struct_group_tagged(fw_iso_packet_hdr, hdr, ... the rest of the members ); u32 header[]; /* tx: Top of 1394 isoch. data_block */ }; With the change described above, we can now declare an object of the type of the tagged struct, without embedding the flexible array in the middle of another struct: struct { struct fw_iso_packet_hdr params; __be32 header[CIP_HEADER_QUADLETS]; } template = { {0}, {0} }; We also use `container_of()` whenever we need to retrieve a pointer to the flexible structure. So, with these changes, fix the following warning: sound/firewire/amdtp-stream.c: In function ‘process_rx_packets’: sound/firewire/amdtp-stream.c:1184:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] 1184 | struct fw_iso_packet params; | Signed-off-by: Gustavo A. R. Silva --- sound/firewire/amdtp-stream.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index c9f153f85ae6..7ba1cd64d7f1 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -1181,12 +1181,14 @@ static void process_rx_packets(struct fw_iso_context *context, u32 tstamp, size_ for (i = 0; i < packets; ++i) { struct { - struct fw_iso_packet params; + struct fw_iso_packet_hdr params; __be32 header[CIP_HEADER_QUADLETS]; } template = { {0}, {0} }; + struct fw_iso_packet *params = + container_of(&template.params, struct fw_iso_packet, hdr); bool sched_irq = false; - build_it_pkt_header(s, desc->cycle, &template.params, pkt_header_length, + build_it_pkt_header(s, desc->cycle, params, pkt_header_length, desc->data_blocks, desc->data_block_counter, desc->syt, i, curr_cycle_time); @@ -1198,7 +1200,7 @@ static void process_rx_packets(struct fw_iso_context *context, u32 tstamp, size_ } } - if (queue_out_packet(s, &template.params, sched_irq) < 0) { + if (queue_out_packet(s, params, sched_irq) < 0) { cancel_stream(s); return; }