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Commit fd3c36f8 authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Linus Torvalds
Browse files

markers: update preempt_disable. call_rcu, rcu_barrier comments 



Add comments requested by Andrew.

Updated comments about synchronize_sched().  Since we use call_rcu and
rcu_barrier now, these comments were out of sync with the code.

Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Mike Mason <mmlnx@us.ibm.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: David Smith <dsmith@redhat.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Adrian Bunk <adrian.bunk@movial.fi>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5a982cbc

kernel/marker.c

+8 −11
Original line number Diff line number Diff line
@@ -104,9 +104,9 @@ void marker_probe_cb(const struct marker *mdata, void *call_private, 
	char ptype;



	/*

	 * disabling preemption to make sure the teardown of the callbacks can

	 * be done correctly when they are in modules and they insure RCU read

	 * coherency.

	 * preempt_disable does two things : disabling preemption to make sure

	 * the teardown of the callbacks can be done correctly when they are in

	 * modules and they insure RCU read coherency.

	 */

	preempt_disable();

	ptype = ACCESS_ONCE(mdata->ptype);
@@ -551,9 +551,9 @@ static int set_marker(struct marker_entry **entry, struct marker *elem, 


/*

 * Disable a marker and its probe callback.

 * Note: only after a synchronize_sched() issued after setting elem->call to the

 * empty function insures that the original callback is not used anymore. This

 * insured by preemption disabling around the call site.

 * Note: only waiting an RCU period after setting elem->call to the empty

 * function insures that the original callback is not used anymore. This insured

 * by preempt_disable around the call site.

 */

static void disable_marker(struct marker *elem)

{
@@ -565,8 +565,8 @@ static void disable_marker(struct marker *elem) 
	elem->ptype = 0;	/* single probe */

	/*

	 * Leave the private data and id there, because removal is racy and

	 * should be done only after a synchronize_sched(). These are never used

	 * until the next initialization anyway.

	 * should be done only after an RCU period. These are never used until

	 * the next initialization anyway.

	 */

}
@@ -601,9 +601,6 @@ void marker_update_probe_range(struct marker *begin, 


/*

 * Update probes, removing the faulty probes.

 * Issues a synchronize_sched() when no reference to the module passed

 * as parameter is found in the probes so the probe module can be

 * safely unloaded from now on.

 *

 * Internal callback only changed before the first probe is connected to it.

 * Single probe private data can only be changed on 0 -> 1 and 2 -> 1