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

Hi,

On Fri, Jan 13, 2023 at 01:04:35PM +0300, Dan Carpenter wrote:

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'.

Thanks for the report. Indeed, I've absolutely overlooked it. I'll fix it enough later with an issue in your previous report for ALSA firewire-motu driver.

Actually, the value of local variable is referred only when tracepoints event is probed, thus the uninitialized bug never occurs. Nevertheless, in a point of coding convention, it's preferable to be initialized.

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

Regards

Takashi Sakamoto