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authorAnanth N Mavinakayanahalli <ananth@in.ibm.com>2005-11-07 01:00:14 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-07 07:53:46 -0800
commitd217d5450f11d8c907c0458d175b0dc999b4d06d (patch)
treeebd68eb9e0b632049d22240a3589887ca27077a5 /arch/ppc64/kernel
parent991a51d83a3d9bebfafdd1e692cf310899d60791 (diff)
[PATCH] Kprobes: preempt_disable/enable() simplification
Reorganize the preempt_disable/enable calls to eliminate the extra preempt depth. Changes based on Paul McKenney's review suggestions for the kprobes RCU changeset. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/ppc64/kernel')
-rw-r--r--arch/ppc64/kernel/kprobes.c25
1 files changed, 15 insertions, 10 deletions
diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c
index e0a25b35437..511af54e623 100644
--- a/arch/ppc64/kernel/kprobes.c
+++ b/arch/ppc64/kernel/kprobes.c
@@ -148,7 +148,14 @@ static inline int kprobe_handler(struct pt_regs *regs)
struct kprobe *p;
int ret = 0;
unsigned int *addr = (unsigned int *)regs->nip;
- struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ struct kprobe_ctlblk *kcb;
+
+ /*
+ * We don't want to be preempted for the entire
+ * duration of kprobe processing
+ */
+ preempt_disable();
+ kcb = get_kprobe_ctlblk();
/* Check we're not actually recursing */
if (kprobe_running()) {
@@ -207,11 +214,6 @@ static inline int kprobe_handler(struct pt_regs *regs)
goto no_kprobe;
}
- /*
- * This preempt_disable() matches the preempt_enable_no_resched()
- * in post_kprobe_handler().
- */
- preempt_disable();
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
set_current_kprobe(p, regs, kcb);
if (p->pre_handler && p->pre_handler(p, regs))
@@ -224,6 +226,7 @@ ss_probe:
return 1;
no_kprobe:
+ preempt_enable_no_resched();
return ret;
}
@@ -296,8 +299,8 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
/*
* By returning a non-zero value, we are telling
- * kprobe_handler() that we have handled unlocking
- * and re-enabling preemption.
+ * kprobe_handler() that we don't want the post_handler
+ * to run (and have re-enabled preemption)
*/
return 1;
}
@@ -385,7 +388,6 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
- rcu_read_lock();
switch (val) {
case DIE_BPT:
if (kprobe_handler(args->regs))
@@ -396,14 +398,16 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
ret = NOTIFY_STOP;
break;
case DIE_PAGE_FAULT:
+ /* kprobe_running() needs smp_processor_id() */
+ preempt_disable();
if (kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
ret = NOTIFY_STOP;
+ preempt_enable();
break;
default:
break;
}
- rcu_read_unlock();
return ret;
}
@@ -440,6 +444,7 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
* saved regs...
*/
memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
+ preempt_enable_no_resched();
return 1;
}