xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

tracing: Make the snapshot trigger work with instances

Browse Source 
The snapshot trigger currently only affects the main ring buffer, even when
it is used by the instances. This can be confusing as the snapshot trigger
is listed in the instance.

 > # cd /sys/kernel/tracing
 > # mkdir instances/foo
 > # echo snapshot > instances/foo/events/syscalls/sys_enter_fchownat/trigger
 > # echo top buffer > trace_marker
 > # echo foo buffer > instances/foo/trace_marker
 > # touch /tmp/bar
 > # chown rostedt /tmp/bar
 > # cat instances/foo/snapshot
 # tracer: nop
 #
 #
 # * Snapshot is freed *
 #
 # Snapshot commands:
 # echo 0 > snapshot : Clears and frees snapshot buffer
 # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated.
 #                      Takes a snapshot of the main buffer.
 # echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free)
 #                      (Doesn't have to be '2' works with any number that
 #                       is not a '0' or '1')

 > # cat snapshot
 # tracer: nop
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
             bash-1189  [000] ....   111.488323: tracing_mark_write: top buffer

Not only did the snapshot occur in the top level buffer, but the instance
snapshot buffer should have been allocated, and it is still free.

Cc: stable@vger.kernel.org
Fixes: 85f2b08268 ("tracing: Add basic event trigger framework")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware)
2018-05-28 10:56:36 -04:00
parent 86b389ff22
commit 2824f50332
3 changed files with 25 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/trace/trace_events_trigger.c
View File

@@ -643,6 +643,7 @@ event_trigger_callback(struct event_command *cmd_ops,
trigger_data->count = -1;
trigger_data->ops = trigger_ops;
trigger_data->cmd_ops = cmd_ops;
trigger_data->private_data = file;
INIT_LIST_HEAD(&trigger_data->list);
INIT_LIST_HEAD(&trigger_data->named_list);
@@ -1054,7 +1055,12 @@ static void
snapshot_trigger(struct event_trigger_data *data, void *rec,
struct ring_buffer_event *event)
{
tracing_snapshot();
struct trace_event_file *file = data->private_data;
if (file)
tracing_snapshot_instance(file->tr);
else
tracing_snapshot();
}
static void
@@ -1077,7 +1083,7 @@ register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
{
int ret = register_trigger(glob, ops, data, file);
if (ret > 0 && tracing_alloc_snapshot() != 0) {
if (ret > 0 && tracing_alloc_snapshot_instance(file->tr) != 0) {
unregister_trigger(glob, ops, data, file);
ret = 0;
}