Re: [Qemu-devel] [PATCH] tests: Fix signalling race condition in TPM tests

[Marc-André Lureau]

On Fri, Sep 7, 2018 at 10:47 PM Stefan Berger
<address@hidden> wrote:
>
> This patch fixes a race condition and test failure where the main process
> waits for the signal of a thread but the thread already sent that signal
> via a condition. Since these signals are non-sticky, we need to introduce a
> separate variable to make this signal sticky.
>
> Signed-off-by: Stefan Berger <address@hidden>

Reviewed-by: Marc-André Lureau <address@hidden>


> ---
>  tests/tpm-crb-test.c |  1 +
>  tests/tpm-emu.c      | 11 ++++++++++-
>  tests/tpm-emu.h      |  1 +
>  tests/tpm-tis-test.c |  1 +
>  4 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/tests/tpm-crb-test.c b/tests/tpm-crb-test.c
> index d8f9569203..6fde579bab 100644
> --- a/tests/tpm-crb-test.c
> +++ b/tests/tpm-crb-test.c
> @@ -151,6 +151,7 @@ int main(int argc, char **argv)
>      test.addr->u.q_unix.path = g_build_filename(tmp_path, "sock", NULL);
>      g_mutex_init(&test.data_mutex);
>      g_cond_init(&test.data_cond);
> +    test.data_cond_signal = false;
>
>      thread = g_thread_new(NULL, tpm_emu_ctrl_thread, &test);
>      tpm_emu_test_wait_cond(&test);
> diff --git a/tests/tpm-emu.c b/tests/tpm-emu.c
> index 8c2bd53cad..125e697181 100644
> --- a/tests/tpm-emu.c
> +++ b/tests/tpm-emu.c
> @@ -23,9 +23,14 @@ void tpm_emu_test_wait_cond(TestState *s)
>      gint64 end_time = g_get_monotonic_time() + 5 * G_TIME_SPAN_SECOND;
>
>      g_mutex_lock(&s->data_mutex);
> -    if (!g_cond_wait_until(&s->data_cond, &s->data_mutex, end_time)) {
> +
> +    if (!s->data_cond_signal &&
> +        !g_cond_wait_until(&s->data_cond, &s->data_mutex, end_time)) {
>          g_assert_not_reached();
>      }
> +
> +    s->data_cond_signal = false;
> +
>      g_mutex_unlock(&s->data_mutex);
>  }
>
> @@ -72,6 +77,10 @@ void *tpm_emu_ctrl_thread(void *data)
>      QIOChannel *ioc;
>
>      qio_channel_socket_listen_sync(lioc, s->addr, &error_abort);
> +
> +    g_mutex_lock(&s->data_mutex);
> +    s->data_cond_signal = true;
> +    g_mutex_unlock(&s->data_mutex);
>      g_cond_signal(&s->data_cond);
>
>      qio_channel_wait(QIO_CHANNEL(lioc), G_IO_IN);
> diff --git a/tests/tpm-emu.h b/tests/tpm-emu.h
> index 08f902485e..8eb802a79e 100644
> --- a/tests/tpm-emu.h
> +++ b/tests/tpm-emu.h
> @@ -26,6 +26,7 @@ struct tpm_hdr {
>  typedef struct TestState {
>      GMutex data_mutex;
>      GCond data_cond;
> +    bool data_cond_signal;
>      SocketAddress *addr;
>      QIOChannel *tpm_ioc;
>      GThread *emu_tpm_thread;
> diff --git a/tests/tpm-tis-test.c b/tests/tpm-tis-test.c
> index 14754d9706..c8ec14888f 100644
> --- a/tests/tpm-tis-test.c
> +++ b/tests/tpm-tis-test.c
> @@ -446,6 +446,7 @@ int main(int argc, char **argv)
>      test.addr->u.q_unix.path = g_build_filename(tmp_path, "sock", NULL);
>      g_mutex_init(&test.data_mutex);
>      g_cond_init(&test.data_cond);
> +    test.data_cond_signal = false;
>
>      thread = g_thread_new(NULL, tpm_emu_ctrl_thread, &test);
>      tpm_emu_test_wait_cond(&test);
> --
> 2.14.4
>
>


-- 
Marc-André Lureau