linux-toradex.git/kernel/trace/trace_events.c, branch v3.10.12

tracing: trace_remove_event_call() should fail if call/file is in use

2013-08-29T16:47:34+00:00

commit 2816c551c796ec14620325b2c9ed75b9979d3125 upstream.

Change trace_remove_event_call(call) to return the error if this
call is active. This is what the callers assume but can't verify
outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c
need the additional changes, unregister_trace_probe() should abort
if trace_remove_event_call() fails.

The caller is going to free this call/file so we must ensure that
nobody can use them after trace_remove_event_call() succeeds.
debugfs should be fine after the previous changes and event_remove()
does TRACE_REG_UNREGISTER, but still there are 2 reasons why we need
the additional checks:

- There could be a perf_event(s) attached to this tp_event, so the
  patch checks ->perf_refcount.

- TRACE_REG_UNREGISTER can be suppressed by FTRACE_EVENT_FL_SOFT_MODE,
  so we simply check FTRACE_EVENT_FL_ENABLED protected by event_mutex.

Link: http://lkml.kernel.org/r/20130729175033.GB26284@redhat.com

Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private

2013-08-29T16:47:34+00:00

commit bf682c3159c4d298d1126a56793ed3f5e80395f7 upstream.

Change remove_event_file_dir() to clear ->i_private for every
file we are going to remove.

We need to check file->dir != NULL because event_create_dir()
can fail. debugfs_remove_recursive(NULL) is fine but the patch
moves it under the same check anyway for readability.

spin_lock(d_lock) and "d_inode != NULL" check are not needed
afaics, but I do not understand this code enough.

tracing_open_generic_file() and tracing_release_generic_file()
can go away, ftrace_enable_fops and ftrace_event_filter_fops()
use tracing_open_generic() but only to check tracing_disabled.

This fixes all races with event_remove() or instance_delete().
f_op->read/write/whatever can never use the freed file/call,
all event/* files were changed to check and use ->i_private
under event_mutex.

Note: this doesn't not fix other problems, event_remove() can
destroy the active ftrace_event_call, we need more changes but
those changes are completely orthogonal.

Link: http://lkml.kernel.org/r/20130728183527.GB16723@redhat.com

Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Introduce remove_event_file_dir()

2013-08-29T16:47:33+00:00

commit f6a84bdc75b5c11621dec58db73fe102cbaf40cc upstream.

Preparation for the next patch. Extract the common code from
remove_event_from_tracers() and __trace_remove_event_dirs()
into the new helper, remove_event_file_dir().

The patch looks more complicated than it actually is, it also
moves remove_subsystem() up to avoid the forward declaration.

Link: http://lkml.kernel.org/r/20130726172547.GA3629@redhat.com

Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Change f_start() to take event_mutex and verify i_private != NULL

2013-08-29T16:47:33+00:00

commit c5a44a1200c6eda2202434f25325e8ad19533fca upstream.

trace_format_open() and trace_format_seq_ops are racy, nothing
protects ftrace_event_call from trace_remove_event_call().

Change f_start() to take event_mutex and verify i_private != NULL,
change f_stop() to drop this lock.

This fixes nothing, but now we can change debugfs_remove("format")
callers to nullify ->i_private and fix the the problem.

Note: the usage of event_mutex is sub-optimal but simple, we can
change this later.

Link: http://lkml.kernel.org/r/20130726172543.GA3622@redhat.com

Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Change event_filter_read/write to verify i_private != NULL

2013-08-29T16:47:33+00:00

commit e2912b091c26b8ea95e5e00a43a7ac620f6c94a6 upstream.

event_filter_read/write() are racy, ftrace_event_call can be already
freed by trace_remove_event_call() callers.

1. Shift mutex_lock(event_mutex) from print/apply_event_filter to
   the callers.

2. Change the callers, event_filter_read() and event_filter_write()
   to read i_private under this mutex and abort if it is NULL.

This fixes nothing, but now we can change debugfs_remove("filter")
callers to nullify ->i_private and fix the the problem.

Link: http://lkml.kernel.org/r/20130726172540.GA3619@redhat.com

Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Change event_enable/disable_read() to verify i_private != NULL

2013-08-29T16:47:33+00:00

commit bc6f6b08dee5645770efb4b76186ded313f23752 upstream.

tracing_open_generic_file() is racy, ftrace_event_file can be
already freed by rmdir or trace_remove_event_call().

Change event_enable_read() and event_disable_read() to read and
verify "file = i_private" under event_mutex.

This fixes nothing, but now we can change debugfs_remove("enable")
callers to nullify ->i_private and fix the the problem.

Link: http://lkml.kernel.org/r/20130726172536.GA3612@redhat.com

Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Turn event/id->i_private into call->event.type

2013-08-29T16:47:33+00:00

commit 1a11126bcb7c93c289bf3218fa546fd3b0c0df8b upstream.

event_id_read() is racy, ftrace_event_call can be already freed
by trace_remove_event_call() callers.

Change event_create_dir() to pass "data = call->event.type", this
is all event_id_read() needs. ftrace_event_id_fops no longer needs
tracing_open_generic().

We add the new helper, event_file_data(), to read ->i_private, it
will have more users.

Note: currently ACCESS_ONCE() and "id != 0" check are not needed,
but we are going to change event_remove/rmdir to clear ->i_private.

Link: http://lkml.kernel.org/r/20130726172532.GA3605@redhat.com

Reviewed-by: Masami Hiramatsu 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Do not call kmem_cache_free() on allocation failure

2013-08-29T16:47:31+00:00

commit aaf6ac0f0871cb7fc0f28f3a00edf329bc7adc29 upstream.

There's no point calling it when _alloc() failed.

Link: http://lkml.kernel.org/r/1370585268-29169-1-git-send-email-namhyung@kernel.org

Signed-off-by: Namhyung Kim 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Miscellaneous fixes for trace_array ref counting

2013-08-04T08:50:42+00:00

commit f77d09a384676bde6445413949d9d2c508ff3e62 upstream.

Some error paths did not handle ref counting properly, and some trace files need
ref counting.

Link: http://lkml.kernel.org/r/1374171524-11948-1-git-send-email-azl@google.com

Signed-off-by: Alexander Z Lam 
Cc: Vaibhav Nagarnaik 
Cc: David Sharp 
Cc: Alexander Z Lam 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing: Add trace_array_get/put() to event handling

2013-07-25T21:07:43+00:00

commit 8e2e2fa47129532a30cff6c25a47078dc97d9260 upstream.

Commit a695cb58162 "tracing: Prevent deleting instances when they are being read"
tried to fix a race between deleting a trace instance and reading contents
of a trace file. But it wasn't good enough. The following could crash the kernel:

 # cd /sys/kernel/debug/tracing/instances
 # ( while :; do mkdir foo; rmdir foo; done ) &
 # ( while :; do echo 1 > foo/events/sched/sched_switch 2> /dev/null; done ) &

Luckily this can only be done by root user, but it should be fixed regardless.

The problem is that a delete of the file can happen after the write to the event
is opened, but before the enabling happens.

The solution is to make sure the trace_array is available before succeeding in
opening for write, and incerment the ref counter while opened.

Now the instance can be deleted when the events are writing to the buffer,
but the deletion of the instance will disable all events before the instance
is actually deleted.

Reported-by: Alexander Lam 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman