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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/ia64
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/ia64')
-rw-r--r--arch/ia64/kernel/kprobes.c37
1 files changed, 20 insertions, 17 deletions
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index fddbac32d44a..96736a119c91 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -389,11 +389,11 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
spin_unlock_irqrestore(&kretprobe_lock, flags);
preempt_enable_no_resched();
- /*
- * By returning a non-zero value, we are telling
- * kprobe_handler() that we have handled unlocking
- * and re-enabling preemption
- */
+ /*
+ * By returning a non-zero value, we are telling
+ * kprobe_handler() that we don't want the post_handler
+ * to run (and have re-enabled preemption)
+ */
return 1;
}
@@ -604,7 +604,14 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
int ret = 0;
struct pt_regs *regs = args->regs;
kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
- 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();
/* Handle recursion cases */
if (kprobe_running()) {
@@ -659,11 +666,6 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
goto no_kprobe;
}
- /*
- * This preempt_disable() matches the preempt_enable_no_resched()
- * in post_kprobes_handler()
- */
- preempt_disable();
set_current_kprobe(p, kcb);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
@@ -681,6 +683,7 @@ ss_probe:
return 1;
no_kprobe:
+ preempt_enable_no_resched();
return ret;
}
@@ -716,9 +719,6 @@ static int __kprobes kprobes_fault_handler(struct pt_regs *regs, int trapnr)
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
- if (!cur)
- return 0;
-
if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
return 1;
@@ -737,7 +737,6 @@ 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_BREAK:
if (pre_kprobes_handler(args))
@@ -748,12 +747,15 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
ret = NOTIFY_STOP;
break;
case DIE_PAGE_FAULT:
- if (kprobes_fault_handler(args->regs, args->trapnr))
+ /* kprobe_running() needs smp_processor_id() */
+ preempt_disable();
+ if (kprobe_running() &&
+ kprobes_fault_handler(args->regs, args->trapnr))
ret = NOTIFY_STOP;
+ preempt_enable();
default:
break;
}
- rcu_read_unlock();
return ret;
}
@@ -785,6 +787,7 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
*regs = kcb->jprobe_saved_regs;
+ preempt_enable_no_resched();
return 1;
}