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| author | Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> | 2008-03-24 12:29:47 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-03-24 19:22:19 -0700 |
| commit | fd3c36f8b527d13cf311d15e0702bc0390956970 (patch) | |
| tree | 7eb9426b914e21e92a7016a54ccc74cc132057ae /kernel/marker.c | |
| parent | 5a982cbc7b3fe6cf72266f319286f29963c71b9e (diff) | |
| download | lwn-fd3c36f8b527d13cf311d15e0702bc0390956970.tar.gz lwn-fd3c36f8b527d13cf311d15e0702bc0390956970.zip | |
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/marker.c')
| -rw-r--r-- | kernel/marker.c | 19 |
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 |