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Re: [PATCH 4/7] kprobes: Support probing module __exit function
- From: Andrew Morton <akpm at linux-foundation dot org>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: ananth at in dot ibm dot com, jkenisto at us dot ibm dot com, davem at davemloft dot net, rusty at rustcorp dot com dot au, linux-kernel at vger dot kernel dot org, systemtap at sources dot redhat dot com
- Date: Thu, 13 Nov 2008 16:27:39 -0800
- Subject: Re: [PATCH 4/7] kprobes: Support probing module __exit function
- References: <4919F19A.9050904@redhat.com>
On Tue, 11 Nov 2008 15:56:58 -0500
Masami Hiramatsu <mhiramat@redhat.com> wrote:
> @@ -69,9 +69,6 @@ struct kprobe {
> /* list of kprobes for multi-handler support */
> struct list_head list;
>
> - /* Indicates that the corresponding module has been ref counted */
> - unsigned int mod_refcounted;
> -
> /*count the number of times this probe was temporarily disarmed */
> unsigned long nmissed;
>
> @@ -103,8 +100,19 @@ struct kprobe {
>
> /* copy of the original instruction */
> struct arch_specific_insn ainsn;
> +
> + /* Indicates various status flags */
> + u32 flags;
> };
>
> +/* Kprobe status flags */
> +#define KPROBE_FLAG_GONE 1 /* breakpoint has already gone */
> +
> +static inline int kprobe_gone(struct kprobe *p)
> +{
> + return p->flags & KPROBE_FLAG_GONE;
> +}
If we're not going to use atomic bitops on kprobe.flags then
modifications to that member will require that the caller hold a lock.
The comment above that member should describe its locking protocol. It
seems that it is kprobe_mutex, so...
--- a/include/linux/kprobes.h~kprobes-support-probing-module-__exit-function-fix
+++ a/include/linux/kprobes.h
@@ -101,7 +101,7 @@ struct kprobe {
/* copy of the original instruction */
struct arch_specific_insn ainsn;
- /* Indicates various status flags */
+ /* Indicates various status flags. Protected by kprobe_mutex. */
u32 flags;
};
_
yes?