From de31c3ca8179d7c21def7ecb56e4fec0c8659d36 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 18 Oct 2010 10:38:58 -0400 Subject: [PATCH] jump label: Fix error with preempt disable holding mutex 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 Acked-by: Masami Hiramatsu Cc: Jason Baron Signed-off-by: Steven Rostedt --- kernel/kprobes.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 9437e14f36bd..9737a76e106f 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -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);