media: venus: hfi_cmds: Replace one-element array with flexible-array member

One-element arrays are deprecated, and we are replacing them with flexible
array members instead. So, replace one-element arrays with flexible-array
members in struct hfi_session_set_buffers_pkt, and refactor the rest of
the code, accordingly.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [1].

This results in no differences in binary output.

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/292
Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Stanimir Varbanov <stanimir.k.varbanov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/platform/qcom/venus/hfi_cmds.c

@@ -200,8 +200,8 @@ int pkt_session_set_buffers(struct hfi_session_set_buffers_pkt *pkt,
 		struct hfi_buffer_info *bi;
 
 		pkt->extradata_size = bd->extradata_size;
-		pkt->shdr.hdr.size = sizeof(*pkt) - sizeof(u32) +
-			(bd->num_buffers * sizeof(*bi));
+		pkt->shdr.hdr.size = sizeof(*pkt) +
+			bd->num_buffers * sizeof(*bi);
 		bi = (struct hfi_buffer_info *)pkt->buffer_info;
 		for (i = 0; i < pkt->num_buffers; i++) {
 			bi->buffer_addr = bd->device_addr;
@@ -210,7 +210,7 @@ int pkt_session_set_buffers(struct hfi_session_set_buffers_pkt *pkt,
 	} else {
 		pkt->extradata_size = 0;
 		pkt->shdr.hdr.size = sizeof(*pkt) +
-			((bd->num_buffers - 1) * sizeof(u32));
+			bd->num_buffers * sizeof(u32);
 		for (i = 0; i < pkt->num_buffers; i++)
 			pkt->buffer_info[i] = bd->device_addr;
 	}
@@ -243,8 +243,8 @@ int pkt_session_unset_buffers(struct hfi_session_release_buffer_pkt *pkt,
 			bi->extradata_addr = bd->extradata_addr;
 		}
 		pkt->shdr.hdr.size =
-				sizeof(struct hfi_session_set_buffers_pkt) -
-				sizeof(u32) + (bd->num_buffers * sizeof(*bi));
+				sizeof(struct hfi_session_set_buffers_pkt) +
+				bd->num_buffers * sizeof(*bi);
 	} else {
 		for (i = 0; i < pkt->num_buffers; i++)
 			pkt->buffer_info[i] = bd->device_addr;
@@ -252,7 +252,7 @@ int pkt_session_unset_buffers(struct hfi_session_release_buffer_pkt *pkt,
 		pkt->extradata_size = 0;
 		pkt->shdr.hdr.size =
 				sizeof(struct hfi_session_set_buffers_pkt) +
-				((bd->num_buffers - 1) * sizeof(u32));
+				bd->num_buffers * sizeof(u32);
 	}
 
 	pkt->response_req = bd->response_required;

drivers/media/platform/qcom/venus/hfi_cmds.h

@@ -117,7 +117,7 @@ struct hfi_session_set_buffers_pkt {
 	u32 extradata_size;
 	u32 min_buffer_size;
 	u32 num_buffers;
-	u32 buffer_info[1];
+	u32 buffer_info[];
 };
 
 struct hfi_session_get_sequence_header_pkt {