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ftrace: Use synchronize_rcu_tasks_rude() instead of ftrace_sync()

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This commit replaces the schedule_on_each_cpu(ftrace_sync) instances
with synchronize_rcu_tasks_rude().

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
[ paulmck: Make Kconfig adjustments noted by kbuild test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney
2020-04-03 12:10:28 -07:00
parent 25246fc831
commit e5a971d76d
2 changed files with 4 additions and 14 deletions
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1
kernel/trace/Kconfig
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@@ -158,6 +158,7 @@ config FUNCTION_TRACER
select CONTEXT_SWITCH_TRACER select CONTEXT_SWITCH_TRACER
select GLOB select GLOB
select TASKS_RCU if PREEMPTION select TASKS_RCU if PREEMPTION
select TASKS_RUDE_RCU
help help
Enable the kernel to trace every kernel function. This is done Enable the kernel to trace every kernel function. This is done
by using a compiler feature to insert a small, 5-byte No-Operation by using a compiler feature to insert a small, 5-byte No-Operation

17
kernel/trace/ftrace.c
View File

@@ -160,17 +160,6 @@ static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
op->saved_func(ip, parent_ip, op, regs); op->saved_func(ip, parent_ip, op, regs);
} }
static void ftrace_sync(struct work_struct *work)
{
/*
* This function is just a stub to implement a hard force
* of synchronize_rcu(). This requires synchronizing
* tasks even in userspace and idle.
*
* Yes, function tracing is rude.
*/
}
static void ftrace_sync_ipi(void *data) static void ftrace_sync_ipi(void *data)
{ {
/* Probably not needed, but do it anyway */ /* Probably not needed, but do it anyway */
@@ -256,7 +245,7 @@ static void update_ftrace_function(void)
* Make sure all CPUs see this. Yes this is slow, but static * Make sure all CPUs see this. Yes this is slow, but static
* tracing is slow and nasty to have enabled. * tracing is slow and nasty to have enabled.
*/ */
schedule_on_each_cpu(ftrace_sync); synchronize_rcu_tasks_rude();
/* Now all cpus are using the list ops. */ /* Now all cpus are using the list ops. */
function_trace_op = set_function_trace_op; function_trace_op = set_function_trace_op;
/* Make sure the function_trace_op is visible on all CPUs */ /* Make sure the function_trace_op is visible on all CPUs */
@@ -2932,7 +2921,7 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command)
* infrastructure to do the synchronization, thus we must do it * infrastructure to do the synchronization, thus we must do it
* ourselves. * ourselves.
*/ */
schedule_on_each_cpu(ftrace_sync); synchronize_rcu_tasks_rude();
/* /*
* When the kernel is preeptive, tasks can be preempted * When the kernel is preeptive, tasks can be preempted
@@ -5887,7 +5876,7 @@ ftrace_graph_release(struct inode *inode, struct file *file)
* infrastructure to do the synchronization, thus we must do it * infrastructure to do the synchronization, thus we must do it
* ourselves. * ourselves.
*/ */
schedule_on_each_cpu(ftrace_sync); synchronize_rcu_tasks_rude();
free_ftrace_hash(old_hash); free_ftrace_hash(old_hash);
} }