From: Steven Rostedt <rostedt@goodmis.org>
To: Filipe Brandenburger <filbranden@google.com>
Cc: Li Zefan <lizefan@huawei.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] tracing: correctly expand len expressions from __dynamic_array macro
Date: Mon, 3 Mar 2014 14:51:10 -0500 [thread overview]
Message-ID: <20140303145110.0c09709c@gandalf.local.home> (raw)
In-Reply-To: <1393651938-16418-2-git-send-email-filbranden@google.com>
On Fri, 28 Feb 2014 21:32:16 -0800
Filipe Brandenburger <filbranden@google.com> wrote:
> This fixes expansion of the len argument in __dynamic_array macros.
> The previous code from commit 7d536cb3f would not fully evaluate the
> expression before multiplying its result by the size of the type.
>
> This went unnoticed because the length stored in the high 16 bits of the
> offset (which is the one that was broken here) is only used by
> filter_pred_strloc which only acts on strings for which the size of the
> type is 1.
>
Was this visible in any of the tracepoints? Should this be marked for
stable? It's been in the kernel for a long time (2009). Or is a new
tracepoint showing a problem?
-- Steve
> Signed-off-by: Filipe Brandenburger <filbranden@google.com>
> ---
> include/trace/ftrace.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
> index 1a8b28d..82e8d89 100644
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -375,7 +375,7 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call) \
> #define __dynamic_array(type, item, len) \
> __data_offsets->item = __data_size + \
> offsetof(typeof(*entry), __data); \
> - __data_offsets->item |= (len * sizeof(type)) << 16; \
> + __data_offsets->item |= ((len) * sizeof(type)) << 16; \
> __data_size += (len) * sizeof(type);
>
> #undef __string
next prev parent reply other threads:[~2014-03-03 19:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-01 5:32 [PATCH 0/3] tracing: fix macro expansion and refactor some of dynamic_array support Filipe Brandenburger
2014-03-01 5:32 ` [PATCH 1/3] tracing: correctly expand len expressions from __dynamic_array macro Filipe Brandenburger
2014-03-03 19:51 ` Steven Rostedt [this message]
2014-03-03 19:57 ` Filipe Brandenburger
2014-03-01 5:32 ` [PATCH 2/3] tracing: evaluate len expression only once in " Filipe Brandenburger
2014-03-01 5:32 ` [PATCH 3/3] tracing: introduce a trace_data_offset struct to store array size Filipe Brandenburger
2014-03-03 20:48 ` Steven Rostedt
2014-03-03 20:59 ` Steven Rostedt
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