[bug report] ALSA: firewire-lib: extend tracepoints event including CYCLE_TIME of 1394 OHCI

[Dan Carpenter <error27@gmail.com>]

Hello Takashi Sakamoto,

The patch fef4e61b0b76: "ALSA: firewire-lib: extend tracepoints event
including CYCLE_TIME of 1394 OHCI" from Jan 10, 2023, leads to the
following Smatch static checker warning:

sound/firewire/amdtp-stream.c:944 generate_tx_packet_descs() error: uninitialized symbol 'curr_cycle_time'.
sound/firewire/amdtp-stream.c:1099 process_rx_packets()	error: uninitialized symbol 'curr_cycle_time'.

sound/firewire/amdtp-stream.c
    1047 static void process_rx_packets(struct fw_iso_context *context, u32 tstamp, size_t header_length,
    1048                                void *header, void *private_data)
    1049 {
    1050         struct amdtp_stream *s = private_data;
    1051         const struct amdtp_domain *d = s->domain;
    1052         const __be32 *ctx_header = header;
    1053         const unsigned int events_per_period = d->events_per_period;
    1054         unsigned int event_count = s->ctx_data.rx.event_count;
    1055         struct pkt_desc *desc = s->packet_descs_cursor;
    1056         unsigned int pkt_header_length;
    1057         unsigned int packets;
    1058         u32 curr_cycle_time;
                 ^^^^^^^^^^^^^^^^^^^

    1059         bool need_hw_irq;
    1060         int i;
    1061 
    1062         if (s->packet_index < 0)
    1063                 return;
    1064 
    1065         // Calculate the number of packets in buffer and check XRUN.
    1066         packets = header_length / sizeof(*ctx_header);
    1067 
    1068         generate_rx_packet_descs(s, desc, ctx_header, packets);
    1069 
    1070         process_ctx_payloads(s, desc, packets);
    1071 
    1072         if (!(s->flags & CIP_NO_HEADER))
    1073                 pkt_header_length = IT_PKT_HEADER_SIZE_CIP;
    1074         else
    1075                 pkt_header_length = 0;
    1076 
    1077         if (s == d->irq_target) {
    1078                 // At NO_PERIOD_WAKEUP mode, the packets for all IT/IR contexts are processed by
    1079                 // the tasks of user process operating ALSA PCM character device by calling ioctl(2)
    1080                 // with some requests, instead of scheduled hardware IRQ of an IT context.
    1081                 struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
    1082                 need_hw_irq = !pcm || !pcm->runtime->no_period_wakeup;
    1083         } else {
    1084                 need_hw_irq = false;
    1085         }
    1086 
    1087         if (trace_amdtp_packet_enabled())
    1088                 (void)fw_card_read_cycle_time(fw_parent_device(s->unit)->card, &curr_cycle_time);

No error checking and no else path.

    1089 
    1090         for (i = 0; i < packets; ++i) {
    1091                 struct {
    1092                         struct fw_iso_packet params;
    1093                         __be32 header[CIP_HEADER_QUADLETS];
    1094                 } template = { {0}, {0} };
    1095                 bool sched_irq = false;
    1096 
    1097                 build_it_pkt_header(s, desc->cycle, &template.params, pkt_header_length,
    1098                                     desc->data_blocks, desc->data_block_counter,
--> 1099                                     desc->syt, i, curr_cycle_time);
                                                           ^^^^^^^^^^^^^^^
Uninitialized.

    1100 
    1101                 if (s == s->domain->irq_target) {
    1102                         event_count += desc->data_blocks;
    1103                         if (event_count >= events_per_period) {
    1104                                 event_count -= events_per_period;
    1105                                 sched_irq = need_hw_irq;
    1106                         }
    1107                 }
    1108 
    1109                 if (queue_out_packet(s, &template.params, sched_irq) < 0) {
    1110                         cancel_stream(s);
    1111                         return;
    1112                 }
    1113 
    1114                 desc = amdtp_stream_next_packet_desc(s, desc);
    1115         }
    1116 
    1117         s->ctx_data.rx.event_count = event_count;
    1118         s->packet_descs_cursor = desc;
    1119 }

regards,
dan carpenter