ALSA: firewire-lib: code refactoring for check of CIP header about payload size

The size of CIP payload is now passed to helper function to parse CIP
header.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210518130048.146596-7-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 1c53067..1ff25e6 100644 (file)
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -574,8 +574,7 @@ static int check_cip_header(struct amdtp_stream *s, const __be32 *buf,
 
        /* Calculate data blocks */
        fdf = (cip_header[1] & CIP_FDF_MASK) >> CIP_FDF_SHIFT;
-       if (payload_length < sizeof(__be32) * 2 ||
-           (fmt == CIP_FMT_AM && fdf == AMDTP_FDF_NO_DATA)) {
+       if (payload_length == 0 || (fmt == CIP_FMT_AM && fdf == AMDTP_FDF_NO_DATA)) {
                *data_blocks = 0;
        } else {
                unsigned int data_block_quadlets =
@@ -590,8 +589,7 @@ static int check_cip_header(struct amdtp_stream *s, const __be32 *buf,
                if (s->flags & CIP_WRONG_DBS)
                        data_block_quadlets = s->data_block_quadlets;
 
-               *data_blocks = (payload_length / sizeof(__be32) - 2) /
-                                                       data_block_quadlets;
+               *data_blocks = payload_length / sizeof(__be32) / data_block_quadlets;
        }
 
        /* Check data block counter continuity */
@@ -658,8 +656,8 @@ static int parse_ir_ctx_header(struct amdtp_stream *s, unsigned int cycle,
        if (cip_header_size > 0) {
                if (payload_length >= cip_header_size) {
                        cip_header = ctx_header + 2;
-                       err = check_cip_header(s, cip_header, payload_length, data_blocks,
-                                              data_block_counter, syt);
+                       err = check_cip_header(s, cip_header, payload_length - cip_header_size,
+                                              data_blocks, data_block_counter, syt);
                        if (err < 0)
                                return err;
                } else {