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author | Steven Rostedt <srostedt@redhat.com> | 2012-08-03 16:10:49 -0400 |
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committer | Steven Rostedt <rostedt@goodmis.org> | 2013-03-15 00:34:44 -0400 |
commit | 277ba04461c2746cf935353474c0961161951b68 (patch) | |
tree | df2b8eb157c6725e606605f6acf40acbd4f13dd6 /kernel/trace/trace_events.c | |
parent | 12ab74ee00d154bc05ea2fc659b7ce6519e5d5a6 (diff) | |
download | linux-stable-277ba04461c2746cf935353474c0961161951b68.tar.gz linux-stable-277ba04461c2746cf935353474c0961161951b68.tar.bz2 linux-stable-277ba04461c2746cf935353474c0961161951b68.zip |
tracing: Add interface to allow multiple trace buffers
Add the interface ("instances" directory) to add multiple buffers
to ftrace. To create a new instance, simply do a mkdir in the
instances directory:
This will create a directory with the following:
# cd instances
# mkdir foo
# ls foo
buffer_size_kb free_buffer trace_clock trace_pipe
buffer_total_size_kb set_event trace_marker tracing_enabled
events/ trace trace_options tracing_on
Currently only events are able to be set, and there isn't a way
to delete a buffer when one is created (yet).
Note, the i_mutex lock is dropped from the parent "instances"
directory during the mkdir operation. As the "instances" directory
can not be renamed or deleted (created on boot), I do not see
any harm in dropping the lock. The creation of the sub directories
is protected by trace_types_lock mutex, which only lets one
instance get into the code path at a time. If two tasks try to
create or delete directories of the same name, only one will occur
and the other will fail with -EEXIST.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace_events.c')
-rw-r--r-- | kernel/trace/trace_events.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 439955239bae..58a61302a733 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1754,16 +1754,22 @@ int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr) struct dentry *d_events; struct dentry *entry; + mutex_lock(&event_mutex); + entry = debugfs_create_file("set_event", 0644, parent, tr, &ftrace_set_event_fops); if (!entry) { pr_warning("Could not create debugfs 'set_event' entry\n"); + mutex_unlock(&event_mutex); return -ENOMEM; } d_events = debugfs_create_dir("events", parent); - if (!d_events) + if (!d_events) { pr_warning("Could not create debugfs 'events' directory\n"); + mutex_unlock(&event_mutex); + return -ENOMEM; + } /* ring buffer internal formats */ trace_create_file("header_page", 0444, d_events, @@ -1778,7 +1784,11 @@ int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr) tr, &ftrace_tr_enable_fops); tr->event_dir = d_events; + down_write(&trace_event_mutex); __trace_add_event_dirs(tr); + up_write(&trace_event_mutex); + + mutex_unlock(&event_mutex); return 0; } |