- Fix adding a new fgraph callback after function graph tracing has
already started.
If the new caller does not initialize its hash before registering the
fgraph_ops, it can cause a NULL pointer dereference. Fix this by adding
a new parameter to ftrace_graph_enable_direct() passing in the newly
added gops directly and not rely on using the fgraph_array[], as entries
in the fgraph_array[] must be initialized. Assign the new gops to the
fgraph_array[] after it goes through ftrace_startup_subops() as that
will properly initialize the gops->ops and initialize its hashes.
- Fix a memory leak in fgraph storage memory test.
If the "multiple fgraph storage on a function" boot up selftest
fails in the registering of the function graph tracer, it will
not free the memory it allocated for the filter. Break the loop
up into two where it allocates the filters first and then registers
the functions where any errors will do the appropriate clean ups.
- Only clear the timerlat timers if it has an associated kthread.
In the rtla tool that uses timerlat, if it was killed just as it
was shutting down, the signals can free the kthread and the timer.
But the closing of the timerlat files could cause the hrtimer_cancel()
to be called on the already freed timer. As the kthread variable is
is set to NULL when the kthreads are stopped and the timers are freed
it can be used to know not to call hrtimer_cancel() on the timer if
the kthread variable is NULL.
- Use a cpumask to keep track of osnoise/timerlat kthreads
The timerlat tracer can use user space threads for its analysis.
With the killing of the rtla tool, the kernel can get confused
between if it is using a user space thread to analyze or one of its
own kernel threads. When this confusion happens, kthread_stop()
can be called on a user space thread and bad things happen.
As the kernel threads are per-cpu, a bitmask can be used to know
when a kernel thread is used or when a user space thread is used.
- Add missing interface_lock to osnoise/timerlat stop_kthread()
The stop_kthread() function in osnoise/timerlat clears the
osnoise kthread variable, and if it was a user space thread does
a put_task on it. But this can race with the closing of the timerlat
files that also does a put_task on the kthread, and if the race happens
the task will have put_task called on it twice and oops.
- Add cond_resched() to the tracing_iter_reset() loop.
The latency tracers keep writing to the ring buffer without resetting
when it issues a new "start" event (like interrupts being disabled).
When reading the buffer with an iterator, the tracing_iter_reset()
sets its pointer to that start event by walking through all the events
in the buffer until it gets to the time stamp of the start event.
In the case of a very large buffer, the loop that looks for the start
event has been reported taking a very long time with a non preempt kernel
that it can trigger a soft lock up warning. Add a cond_resched() into
that loop to make sure that doesn't happen.
- Use list_del_rcu() for eventfs ei->list variable
It was reported that running loops of creating and deleting kprobe events
could cause a crash due to the eventfs list iteration hitting a LIST_POISON
variable. This is because the list is protected by SRCU but when an item is
deleted from the list, it was using list_del() which poisons the "next"
pointer. This is what list_del_rcu() was to prevent.
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Merge tag 'trace-v6.11-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Fix adding a new fgraph callback after function graph tracing has
already started.
If the new caller does not initialize its hash before registering the
fgraph_ops, it can cause a NULL pointer dereference. Fix this by
adding a new parameter to ftrace_graph_enable_direct() passing in the
newly added gops directly and not rely on using the fgraph_array[],
as entries in the fgraph_array[] must be initialized.
Assign the new gops to the fgraph_array[] after it goes through
ftrace_startup_subops() as that will properly initialize the
gops->ops and initialize its hashes.
- Fix a memory leak in fgraph storage memory test.
If the "multiple fgraph storage on a function" boot up selftest fails
in the registering of the function graph tracer, it will not free the
memory it allocated for the filter. Break the loop up into two where
it allocates the filters first and then registers the functions where
any errors will do the appropriate clean ups.
- Only clear the timerlat timers if it has an associated kthread.
In the rtla tool that uses timerlat, if it was killed just as it was
shutting down, the signals can free the kthread and the timer. But
the closing of the timerlat files could cause the hrtimer_cancel() to
be called on the already freed timer. As the kthread variable is is
set to NULL when the kthreads are stopped and the timers are freed it
can be used to know not to call hrtimer_cancel() on the timer if the
kthread variable is NULL.
- Use a cpumask to keep track of osnoise/timerlat kthreads
The timerlat tracer can use user space threads for its analysis. With
the killing of the rtla tool, the kernel can get confused between if
it is using a user space thread to analyze or one of its own kernel
threads. When this confusion happens, kthread_stop() can be called on
a user space thread and bad things happen. As the kernel threads are
per-cpu, a bitmask can be used to know when a kernel thread is used
or when a user space thread is used.
- Add missing interface_lock to osnoise/timerlat stop_kthread()
The stop_kthread() function in osnoise/timerlat clears the osnoise
kthread variable, and if it was a user space thread does a put_task
on it. But this can race with the closing of the timerlat files that
also does a put_task on the kthread, and if the race happens the task
will have put_task called on it twice and oops.
- Add cond_resched() to the tracing_iter_reset() loop.
The latency tracers keep writing to the ring buffer without resetting
when it issues a new "start" event (like interrupts being disabled).
When reading the buffer with an iterator, the tracing_iter_reset()
sets its pointer to that start event by walking through all the
events in the buffer until it gets to the time stamp of the start
event. In the case of a very large buffer, the loop that looks for
the start event has been reported taking a very long time with a non
preempt kernel that it can trigger a soft lock up warning. Add a
cond_resched() into that loop to make sure that doesn't happen.
- Use list_del_rcu() for eventfs ei->list variable
It was reported that running loops of creating and deleting kprobe
events could cause a crash due to the eventfs list iteration hitting
a LIST_POISON variable. This is because the list is protected by SRCU
but when an item is deleted from the list, it was using list_del()
which poisons the "next" pointer. This is what list_del_rcu() was to
prevent.
* tag 'trace-v6.11-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing/timerlat: Add interface_lock around clearing of kthread in stop_kthread()
tracing/timerlat: Only clear timer if a kthread exists
tracing/osnoise: Use a cpumask to know what threads are kthreads
eventfs: Use list_del_rcu() for SRCU protected list variable
tracing: Avoid possible softlockup in tracing_iter_reset()
tracing: Fix memory leak in fgraph storage selftest
tracing: fgraph: Fix to add new fgraph_ops to array after ftrace_startup_subops()
e4b42053b7