Messages in this thread Patch in this message | | | Subject | Re: [PATCH 4/9] jump label: Fix deadlock b/w jump_label_mutex vs. text_mutex | From | Steven Rostedt <> | Date | Fri, 15 Oct 2010 22:25:49 -0400 |
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On Fri, 2010-10-15 at 22:55 +0200, Peter Zijlstra wrote: > On Fri, 2010-10-15 at 16:09 -0400, Steven Rostedt wrote: > > +void jump_label_lock(void) > > +{ > > + mutex_lock(&jump_label_mutex); > > +} > > + > > > +++ b/kernel/kprobes.c > > @@ -1145,13 +1145,16 @@ int __kprobes register_kprobe(struct kprobe *p) > > return ret; > > > > preempt_disable(); > > + jump_label_lock(); > > How exactly does that work? >
This patch should fix it (compiled tested only). If all agree, I'll add it to the series.
-- Steve
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index d45d72e..0dbd328 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1144,17 +1144,13 @@ 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; @@ -1168,10 +1164,9 @@ 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. @@ -1179,11 +1174,11 @@ 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); @@ -1225,6 +1220,11 @@ out: module_put(probed_mod); return ret; + +fail_with_jump_label: + preempt_enable(); + jump_label_unlock(); + return -EINVAL; } EXPORT_SYMBOL_GPL(register_kprobe);
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