libbpf-tools: fix runqlen's error handling logic

Signed-off-by: Wenbo Zhang <ethercflow@gmail.com>

diff --git a/libbpf-tools/runqlen.c b/libbpf-tools/runqlen.c
index 453ab0955cf1bffdfa6e965d369debe9a076b84b..4c5ed2de9cf1b1a9f540c125de3be688043e80b2 100644 (file)
--- a/libbpf-tools/runqlen.c
+++ b/libbpf-tools/runqlen.c
@@ -18,8 +18,6 @@
 #include "runqlen.skel.h"
 #include "trace_helpers.h"
 
-#define FREQ   99
-
 #define max(x, y) ({                            \
        typeof(x) _max1 = (x);                   \
        typeof(y) _max2 = (y);                   \
@@ -31,11 +29,13 @@ struct env {
        bool runqocc;
        bool timestamp;
        time_t interval;
+       bool freq;
        int times;
        bool verbose;
 } env = {
        .interval = 99999999,
        .times = 99999999,
+       .freq = 99,
 };
 
 static volatile bool exiting;
@@ -45,17 +45,19 @@ const char *argp_program_bug_address = "<bpf@vger.kernel.org>";
 const char argp_program_doc[] =
 "Summarize scheduler run queue length as a histogram.\n"
 "\n"
-"USAGE: runqlen [--help] [-C] [-O] [-T] [interval] [count]\n"
+"USAGE: runqlen [--help] [-C] [-O] [-T] [-f FREQUENCY] [interval] [count]\n"
 "\n"
 "EXAMPLES:\n"
 "    runqlen         # summarize run queue length as a histogram\n"
 "    runqlen 1 10    # print 1 second summaries, 10 times\n"
 "    runqlen -T 1    # 1s summaries and timestamps\n"
 "    runqlen -O      # report run queue occupancy\n"
-"    runqlen -C      # show each CPU separately\n";
+"    runqlen -C      # show each CPU separately\n"
+"    runqlen -f 199  # sample at 199HZ\n";
 
 static const struct argp_option opts[] = {
        { "cpus", 'C', NULL, 0, "Print output for each CPU separately" },
+       { "frequency", 'f', "FREQUENCY", 0, "Sample with a certain frequency" },
        { "runqocc", 'O', NULL, 0, "Report run queue occupancy" },
        { "timestamp", 'T', NULL, 0, "Include timestamp on output" },
        { "verbose", 'v', NULL, 0, "Verbose debug output" },
@@ -79,6 +81,14 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
        case 'T':
                env.timestamp = true;
                break;
+       case 'f':
+               errno = 0;
+               env.freq = strtol(arg, NULL, 10);
+               if (errno || env.freq <= 0) {
+                       fprintf(stderr, "Invalid freq (in hz): %s\n", arg);
+                       argp_usage(state);
+               }
+               break;
        case ARGP_KEY_ARG:
                errno = 0;
                if (pos_args == 0) {
@@ -122,6 +132,9 @@ static int open_and_attach_perf_event(int freq, struct bpf_program *prog,
        for (i = 0; i < nr_cpus; i++) {
                fd = syscall(__NR_perf_event_open, &attr, -1, i, -1, 0);
                if (fd < 0) {
+                       /* Ignore CPU that is offline */
+                       if (errno == ENODEV)
+                               continue;
                        fprintf(stderr, "failed to init perf sampling: %s\n",
                                strerror(errno));
                        return -1;
@@ -203,7 +216,7 @@ int main(int argc, char **argv)
                .parser = parse_arg,
                .doc = argp_program_doc,
        };
-       struct bpf_link **links = NULL;
+       struct bpf_link *links[MAX_CPU_NR] = {};
        struct runqlen_bpf *obj;
        struct tm *tm;
        char ts[32];
@@ -222,22 +235,22 @@ int main(int argc, char **argv)
                return 1;
        }
 
-       obj = runqlen_bpf__open();
-       if (!obj) {
-               fprintf(stderr, "failed to open and/or load BPF object\n");
+       nr_cpus = libbpf_num_possible_cpus();
+       if (nr_cpus < 0) {
+               printf("failed to get # of possible cpus: '%s'!\n",
+                      strerror(-nr_cpus));
                return 1;
        }
-
-       nr_cpus = libbpf_num_possible_cpus();
        if (nr_cpus > MAX_CPU_NR) {
-               fprintf(stderr, "The number of cpu cores is too much, please "
+               fprintf(stderr, "the number of cpu cores is too big, please "
                        "increase MAX_CPU_NR's value and recompile");
                return 1;
        }
-       links = calloc(nr_cpus, sizeof(*links));
-       if (!links) {
-               fprintf(stderr, "failed to alloc links\n");
-               goto cleanup;
+
+       obj = runqlen_bpf__open();
+       if (!obj) {
+               fprintf(stderr, "failed to open BPF object\n");
+               return 1;
        }
 
        /* initialize global data (filtering options) */
@@ -249,7 +262,8 @@ int main(int argc, char **argv)
                goto cleanup;
        }
 
-       if (open_and_attach_perf_event(FREQ, obj->progs.do_sample, links))
+       err = open_and_attach_perf_event(env.freq, obj->progs.do_sample, links);
+       if (err)
                goto cleanup;
 
        printf("Sampling run queue length... Hit Ctrl-C to end.\n");
@@ -279,7 +293,6 @@ int main(int argc, char **argv)
 cleanup:
        for (i = 0; i < nr_cpus; i++)
                bpf_link__destroy(links[i]);
-       free(links);
        runqlen_bpf__destroy(obj);
 
        return err != 0;