kprobes: Disable booster when CONFIG_PREEMPT=y
Disable kprobe booster when CONFIG_PREEMPT=y at this time,
because it can't ensure that all kernel threads preempted on
kprobe's boosted slot run out from the slot even using
freeze_processes().
The booster on preemptive kernel will be resumed if
synchronize_tasks() or something like that is introduced.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100202214904.4694.24330.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index b7df302..9907a03 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -124,30 +124,6 @@
static int kprobe_garbage_slots;
static int collect_garbage_slots(void);
-static int __kprobes check_safety(void)
-{
- int ret = 0;
-#if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER)
- ret = freeze_processes();
- if (ret == 0) {
- struct task_struct *p, *q;
- do_each_thread(p, q) {
- if (p != current && p->state == TASK_RUNNING &&
- p->pid != 0) {
- printk("Check failed: %s is running\n",p->comm);
- ret = -1;
- goto loop_end;
- }
- } while_each_thread(p, q);
- }
-loop_end:
- thaw_processes();
-#else
- synchronize_sched();
-#endif
- return ret;
-}
-
/**
* __get_insn_slot() - Find a slot on an executable page for an instruction.
* We allocate an executable page if there's no room on existing ones.
@@ -235,9 +211,8 @@
{
struct kprobe_insn_page *kip, *next;
- /* Ensure no-one is preepmted on the garbages */
- if (check_safety())
- return -EAGAIN;
+ /* Ensure no-one is interrupted on the garbages */
+ synchronize_sched();
list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) {
int i;