Commit e5a971d7 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

ftrace: Use synchronize_rcu_tasks_rude() instead of ftrace_sync() 



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

Suggested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
[ paulmck: Make Kconfig adjustments noted by kbuild test robot. ]
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 25246fc8

kernel/trace/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -158,6 +158,7 @@ config FUNCTION_TRACER 
	select CONTEXT_SWITCH_TRACER

	select GLOB

	select TASKS_RCU if PREEMPTION

	select TASKS_RUDE_RCU

	help

	  Enable the kernel to trace every kernel function. This is done

	  by using a compiler feature to insert a small, 5-byte No-Operation

kernel/trace/ftrace.c

+3 −14
Original line number Diff line number Diff line
@@ -160,17 +160,6 @@ static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip, 
	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)

{

	/* 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

	 * 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. */

	function_trace_op = set_function_trace_op;

	/* 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

		 * ourselves.

		 */

		schedule_on_each_cpu(ftrace_sync);

		synchronize_rcu_tasks_rude();



		/*

		 * 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

		 * ourselves.

		 */

		schedule_on_each_cpu(ftrace_sync);

		synchronize_rcu_tasks_rude();



		free_ftrace_hash(old_hash);

	}