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authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>2008-03-24 12:29:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-03-24 19:22:19 -0700
commitfd3c36f8b527d13cf311d15e0702bc0390956970 (patch)
tree7eb9426b914e21e92a7016a54ccc74cc132057ae /kernel
parent5a982cbc7b3fe6cf72266f319286f29963c71b9e (diff)
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 <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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/marker.c19
1 files changed, 8 insertions, 11 deletions
diff --git a/kernel/marker.c b/kernel/marker.c
index 48a4ea5afffd..ccae1d10e32f 100644
--- a/kernel/marker.c
+++ b/kernel/marker.c
@@ -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

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