[PATCH 7/9] Task Watchers v2: Register lockdep task watcher

[Matt Helsley <matthltc@us.ibm.com>]

Register a task watcher for lockdep instead of hooking into copy_process().

Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
---
 kernel/fork.c    |    5 -----
 kernel/lockdep.c |    9 +++++++++
 2 files changed, 9 insertions(+), 5 deletions(-)

Benchmark results:
System: 4 1.7GHz ppc64 (Power 4+) processors, 30968600MB RAM, 2.6.19-rc2-mm2 kernel

Clone	Number of Children Cloned
	5000		7500		10000		12500		15000		17500
	---------------------------------------------------------------------------------------
Mean	17808.2 	18092.3 	18215.5 	18183.6 	18310.8 	18342.8
Dev	302.333 	317.786 	303.385 	280.608 	281.378 	294.009
Err (%)	1.69772 	1.75647 	1.66553 	1.5432	 	1.53668 	1.60285

Fork	Number of Children Forked
	5000		7500		10000		12500		15000		17500
	---------------------------------------------------------------------------------------
Mean	17821.8 	18025.1 	18112.5 	18226	 	18217.4 	18318
Dev	316.497 	310.195 	291.372 	297.166 	364.908 	293.89
Err (%)	1.7759 		1.7209 		1.60868 	1.63045 	2.00307 	1.60438

Kernbench:
Elapsed: 124.333s User: 439.787s System: 46.491s CPU: 390.7%
439.67user 46.42system 2:04.09elapsed 391%CPU (0avgtext+0avgdata 0maxresident)k
439.82user 46.46system 2:04.17elapsed 391%CPU (0avgtext+0avgdata 0maxresident)k
439.75user 46.65system 2:04.24elapsed 391%CPU (0avgtext+0avgdata 0maxresident)k
439.79user 46.43system 2:04.54elapsed 390%CPU (0avgtext+0avgdata 0maxresident)k
439.71user 46.43system 2:04.56elapsed 390%CPU (0avgtext+0avgdata 0maxresident)k
439.71user 46.51system 2:04.45elapsed 390%CPU (0avgtext+0avgdata 0maxresident)k
439.86user 46.64system 2:04.69elapsed 390%CPU (0avgtext+0avgdata 0maxresident)k
439.87user 46.44system 2:04.05elapsed 392%CPU (0avgtext+0avgdata 0maxresident)k
439.87user 46.48system 2:04.63elapsed 390%CPU (0avgtext+0avgdata 0maxresident)k
439.82user 46.45system 2:03.91elapsed 392%CPU (0avgtext+0avgdata 0maxresident)k

Index: linux-2.6.19-rc2-mm2/kernel/fork.c
===================================================================
--- linux-2.6.19-rc2-mm2.orig/kernel/fork.c
+++ linux-2.6.19-rc2-mm2/kernel/fork.c
@@ -1052,15 +1052,10 @@ static struct task_struct *copy_process(
 		p->tgid = current->tgid;
 
 	retval = notify_task_watchers(WATCH_TASK_INIT, clone_flags, p);
 	if (retval < 0)
 		goto bad_fork_cleanup_delays_binfmt;
-#ifdef CONFIG_LOCKDEP
-	p->lockdep_depth = 0; /* no locks held yet */
-	p->curr_chain_key = 0;
-	p->lockdep_recursion = 0;
-#endif
 
 #ifdef CONFIG_DEBUG_MUTEXES
 	p->blocked_on = NULL; /* not blocked yet */
 #endif
 
Index: linux-2.6.19-rc2-mm2/kernel/lockdep.c
===================================================================
--- linux-2.6.19-rc2-mm2.orig/kernel/lockdep.c
+++ linux-2.6.19-rc2-mm2/kernel/lockdep.c
@@ -2556,10 +2556,19 @@ void __init lockdep_init(void)
 		INIT_LIST_HEAD(chainhash_table + i);
 
 	lockdep_initialized = 1;
 }
 
+static int init_task_lockdep(unsigned long clone_flags, struct task_struct *p)
+{
+	p->lockdep_depth = 0; /* no locks held yet */
+	p->curr_chain_key = 0;
+	p->lockdep_recursion = 0;
+	return 0;
+}
+task_watcher_func(init, init_task_lockdep);
+
 void __init lockdep_info(void)
 {
 	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
 
 	printk("... MAX_LOCKDEP_SUBCLASSES:    %lu\n", MAX_LOCKDEP_SUBCLASSES);

--
-
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