Fix: lttng_event_notifier_group_error_counter_cmd does not respect caller convention

The callers of lttng_event_notifier_group_error_counter_cmd (via
callback) expects that, on success, the object for which the ownership was
taken be set to -1 or NULL.

In this case, the shm_fd filed was not set to -1. Resulting in the
caller closing the fd and leading to errors on subsequent call.

e.g:
 sample: lttng-ust-fd-tracker.c:300: int lttng_ust_add_fd_to_tracker(int): Assertion `!IS_FD_SET(fd, lttng_fd_set)' failed.
 Error: Error sending counter cpu data to UST tracer: status=APP_DEAD
 Error: Failed to setup event notifier error accounting for app
 ./test.sh: line 5: 2650455 Aborted                 (core dumped) ../lttng-ust/doc/examples/easy-ust/sample
 lttng-sessiond: ustctl.c:192: int ustctl_release_object(int, struct lttng_ust_object_data *): Assertion `0' failed.

Change-Id: I79b242768cf7d27cd9a50c31b56423c8de08abd5
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/liblttng-ust/lttng-ust-abi.c b/liblttng-ust/lttng-ust-abi.c
index 62e1be74c1232ca31cee54c83f90df2b4bf51320..8fd2e95806e792c6a4e501de3931940cf57e8494 100644 (file)
--- a/liblttng-ust/lttng-ust-abi.c
+++ b/liblttng-ust/lttng-ust-abi.c
@@ -733,21 +733,32 @@ static
 long lttng_event_notifier_group_error_counter_cmd(int objd, unsigned int cmd, unsigned long arg,
        union ust_args *uargs, void *owner)
 {
+       int ret;
        struct lttng_counter *counter = objd_private(objd);
 
        switch (cmd) {
        case LTTNG_UST_COUNTER_GLOBAL:
-               return -EINVAL;         /* Unimplemented. */
+               ret = -EINVAL;  /* Unimplemented. */
+               break;
        case LTTNG_UST_COUNTER_CPU:
        {
                struct lttng_ust_counter_cpu *counter_cpu =
                        (struct lttng_ust_counter_cpu *)arg;
-               return lttng_counter_set_cpu_shm(counter->counter,
+
+               ret = lttng_counter_set_cpu_shm(counter->counter,
                        counter_cpu->cpu_nr, uargs->counter_shm.shm_fd);
+               if (!ret) {
+                       /* Take ownership of the shm_fd. */
+                       uargs->counter_shm.shm_fd = -1;
+               }
+               break;
        }
        default:
-               return -EINVAL;
+               ret = -EINVAL;
+               break;
        }
+
+       return ret;
 }
 
 LTTNG_HIDDEN