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jump label: Fix error with preempt disable holding mutex

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Kprobes and jump label were having a race between mutexes that
was fixed by reordering the jump label. But this reordering
moved the jump label mutex into a preempt disable location.

This patch does a little fiddling to move the grabbing of
the jump label mutex from inside the preempt disable section
and still keep the order correct between the mutex and the
kprobes lock.

Reported-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2010-10-18 10:38:58 -04:00 committed by Steven Rostedt
parent 91bad2f8d3
commit de31c3ca81
1 changed files with 13 additions and 13 deletions
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26
kernel/kprobes.c
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@ -1145,17 +1145,13 @@ int __kprobes register_kprobe(struct kprobe *p)
if (ret)
return ret;
preempt_disable();
jump_label_lock();
preempt_disable();
if (!kernel_text_address((unsigned long) p->addr) ||
in_kprobes_functions((unsigned long) p->addr) ||
ftrace_text_reserved(p->addr, p->addr) ||
jump_label_text_reserved(p->addr, p->addr)) {
preempt_enable();
jump_label_unlock();
return -EINVAL;
}
jump_label_unlock();
jump_label_text_reserved(p->addr, p->addr))
goto fail_with_jump_label;
/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
p->flags &= KPROBE_FLAG_DISABLED;
@ -1169,10 +1165,9 @@ int __kprobes register_kprobe(struct kprobe *p)
* We must hold a refcount of the probed module while updating
* its code to prohibit unexpected unloading.
*/
if (unlikely(!try_module_get(probed_mod))) {
preempt_enable();
return -EINVAL;
}
if (unlikely(!try_module_get(probed_mod)))
goto fail_with_jump_label;
/*
* If the module freed .init.text, we couldn't insert
* kprobes in there.
@ -1180,11 +1175,11 @@ int __kprobes register_kprobe(struct kprobe *p)
if (within_module_init((unsigned long)p->addr, probed_mod) &&
probed_mod->state != MODULE_STATE_COMING) {
module_put(probed_mod);
preempt_enable();
return -EINVAL;
goto fail_with_jump_label;
}
}
preempt_enable();
jump_label_unlock();
p->nmissed = 0;
INIT_LIST_HEAD(&p->list);
@ -1226,6 +1221,11 @@ out:
module_put(probed_mod);
return ret;
fail_with_jump_label:
preempt_enable();
jump_label_unlock();
return -EINVAL;
}
EXPORT_SYMBOL_GPL(register_kprobe);