|author||Mathieu Desnoyers <firstname.lastname@example.org>||2008-03-24 12:29:47 -0700|
|committer||Linus Torvalds <email@example.com>||2008-03-24 19:22:19 -0700|
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: Mathieu Desnoyers <firstname.lastname@example.org> Cc: Christoph Hellwig <email@example.com> Cc: Mike Mason <firstname.lastname@example.org> Cc: Dipankar Sarma <email@example.com> Cc: David Smith <firstname.lastname@example.org> Cc: "Paul E. McKenney" <email@example.com> Cc: Steven Rostedt <firstname.lastname@example.org> Cc: Adrian Bunk <email@example.com> Signed-off-by: Andrew Morton <firstname.lastname@example.org> Signed-off-by: Linus Torvalds <email@example.com>
1 files changed, 8 insertions, 11 deletions
diff --git a/kernel/marker.c b/kernel/marker.c
index 48a4ea5afffd..ccae1d10e32f 100644
@@ -104,9 +104,9 @@ void marker_probe_cb(const struct marker *mdata, void *call_private,
- * 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.
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