From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Matt Mullins <mmullins@mmlx.us>, Ingo Molnar <mingo@redhat.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Dmitry Vyukov <dvyukov@google.com>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>, netdev <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH] tracepoint: Do not fail unregistering a probe due to memory allocation
Date: Tue, 17 Nov 2020 14:21:45 -0500 [thread overview]
Message-ID: <20201117142145.43194f1a@gandalf.local.home> (raw)
In-Reply-To: <47463878.48157.1605640510560.JavaMail.zimbra@efficios.com>
On Tue, 17 Nov 2020 14:15:10 -0500 (EST)
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h
> index e7c2276be33e..e0351bb0b140 100644
> --- a/include/linux/tracepoint-defs.h
> +++ b/include/linux/tracepoint-defs.h
> @@ -38,6 +38,7 @@ struct tracepoint {
> int (*regfunc)(void);
> void (*unregfunc)(void);
> struct tracepoint_func __rcu *funcs;
> + void *stub_func;
> };
>
> #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 0f21617f1a66..b0b805de3779 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -287,6 +287,9 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
> #define DEFINE_TRACE_FN(_name, _reg, _unreg, proto, args) \
> static const char __tpstrtab_##_name[] \
> __section("__tracepoints_strings") = #_name; \
> + static void __cold __tracepoint_stub_func_##_name(void *__data, proto) \
> + { \
> + } \
The thing is, tracepoints are already bloated. I do not want to add
something like this that will unnecessarily add more text.
Since all tracepoints callbacks have at least one parameter (__data), we
could declare tp_stub_func as:
static void tp_stub_func(void *data, ...)
{
return;
}
And now C knows that tp_stub_func() can be called with one or more
parameters, and had better be able to deal with it!
-- Steve
> extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name); \
> int __traceiter_##_name(void *__data, proto); \
> struct tracepoint __tracepoint_##_name __used \
> @@ -298,7 +301,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
> .iterator = &__traceiter_##_name, \
> .regfunc = _reg, \
> .unregfunc = _unreg, \
> - .funcs = NULL }; \
> + .funcs = NULL, \
> + .stub_func = __tracepoint_stub_func_##_name, }; \
> __TRACEPOINT_ENTRY(_name); \
> int __traceiter_##_name(void *__data, proto) \
> { \
>
> Thanks,
>
> Mathieu
>
next prev parent reply other threads:[~2020-11-17 19:22 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 22:51 [PATCH] tracepoint: Do not fail unregistering a probe due to memory allocation Steven Rostedt
2020-11-16 23:16 ` Steven Rostedt
2020-11-17 19:15 ` Mathieu Desnoyers
2020-11-17 19:21 ` Steven Rostedt [this message]
2020-11-17 19:47 ` Mathieu Desnoyers
2020-11-17 20:34 ` Steven Rostedt
2020-11-17 20:58 ` Steven Rostedt
2020-11-17 21:22 ` Mathieu Desnoyers
2020-11-17 22:16 ` Steven Rostedt
2020-11-17 23:08 ` Mathieu Desnoyers
2020-11-18 1:11 ` Steven Rostedt
2020-11-17 21:08 ` Mathieu Desnoyers
2020-11-18 13:21 ` violating function pointer signature Peter Zijlstra
2020-11-18 13:59 ` Florian Weimer
2020-11-18 14:12 ` Peter Zijlstra
2020-11-18 14:18 ` Florian Weimer
2020-11-18 14:34 ` [PATCH v3] tracepoint: Do not fail unregistering a probe due to memory allocation Steven Rostedt
2020-11-24 5:59 ` Matt Mullins
2020-11-18 14:22 ` violating function pointer signature Steven Rostedt
2020-11-18 19:46 ` Alexei Starovoitov
2020-11-18 20:02 ` Steven Rostedt
2020-11-18 14:02 ` Steven Rostedt
2020-11-18 16:01 ` Mathieu Desnoyers
2020-11-18 16:19 ` David Laight
2020-11-18 16:50 ` Nick Desaulniers
2020-11-18 17:17 ` Steven Rostedt
2020-11-18 18:12 ` Segher Boessenkool
2020-11-18 18:31 ` Florian Weimer
2020-11-18 18:55 ` Segher Boessenkool
2020-11-18 18:58 ` Steven Rostedt
2020-11-18 18:59 ` Steven Rostedt
2020-11-18 19:11 ` Segher Boessenkool
2020-11-18 19:33 ` Steven Rostedt
2020-11-18 19:48 ` Segher Boessenkool
2020-11-18 20:44 ` Steven Rostedt
2020-11-19 8:21 ` Peter Zijlstra
2020-11-19 8:36 ` Peter Zijlstra
2020-11-19 14:37 ` Segher Boessenkool
2020-11-19 14:59 ` Steven Rostedt
2020-11-19 16:35 ` Segher Boessenkool
2020-11-19 17:42 ` David Laight
2020-11-19 19:27 ` Segher Boessenkool
2020-11-19 17:04 ` Alexei Starovoitov
2020-11-19 17:30 ` Steven Rostedt
2020-11-20 1:31 ` Nick Desaulniers
2020-11-17 21:33 ` [PATCH] tracepoint: Do not fail unregistering a probe due to memory allocation Kees Cook
2020-11-17 22:19 ` Steven Rostedt
2020-11-17 23:12 ` Mathieu Desnoyers
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