selftests/bpf: Add send_signal_sched_switch test

Added one test, send_signal_sched_switch, to test bpf_send_signal()
helper triggered by sched/sched_switch tracepoint. This test can be used
to verify kernel deadlocks fixed by the previous commit. The test itself
is heavily borrowed from Commit eac9153f2b58 ("bpf/stackmap: Fix deadlock
with rq_lock in bpf_get_stack()").

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200304191105.2796601-1-yhs@fb.com

diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal_sched_switch.c b/tools/testing/selftests/bpf/prog_tests/send_signal_sched_switch.c
new file mode 100644 (file)
index 0000000..189a34a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/send_signal_sched_switch.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <pthread.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "test_send_signal_kern.skel.h"
+
+static void sigusr1_handler(int signum)
+{
+}
+
+#define THREAD_COUNT 100
+
+static void *worker(void *p)
+{
+       int i;
+
+       for ( i = 0; i < 1000; i++)
+               usleep(1);
+
+       return NULL;
+}
+
+void test_send_signal_sched_switch(void)
+{
+       struct test_send_signal_kern *skel;
+       pthread_t threads[THREAD_COUNT];
+       u32 duration = 0;
+       int i, err;
+
+       signal(SIGUSR1, sigusr1_handler);
+
+       skel = test_send_signal_kern__open_and_load();
+       if (CHECK(!skel, "skel_open_and_load", "skeleton open_and_load failed\n"))
+               return;
+
+       skel->bss->pid = getpid();
+       skel->bss->sig = SIGUSR1;
+
+       err = test_send_signal_kern__attach(skel);
+       if (CHECK(err, "skel_attach", "skeleton attach failed\n"))
+               goto destroy_skel;
+
+       for (i = 0; i < THREAD_COUNT; i++) {
+               err = pthread_create(threads + i, NULL, worker, NULL);
+               if (CHECK(err, "pthread_create", "Error creating thread, %s\n",
+                         strerror(errno)))
+                       goto destroy_skel;
+       }
+
+       for (i = 0; i < THREAD_COUNT; i++)
+               pthread_join(threads[i], NULL);
+
+destroy_skel:
+       test_send_signal_kern__destroy(skel);
+}

diff --git a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
index 1acc91e..b4233d3 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
@@ -31,6 +31,12 @@ int send_signal_tp(void *ctx)
        return bpf_send_signal_test(ctx);
 }
 
+SEC("tracepoint/sched/sched_switch")
+int send_signal_tp_sched(void *ctx)
+{
+       return bpf_send_signal_test(ctx);
+}
+
 SEC("perf_event")
 int send_signal_perf(void *ctx)
 {