From patchwork Thu Feb 22 19:51:13 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13568053 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3BFDD6E5F0; Thu, 22 Feb 2024 19:50:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708631415; cv=none; b=BXZemLbkIiEN9uFhw3/qhECgVgshDzpmiE/I7y3rzWjpiHy83uwAdDh4ZGwLWf3jK/Zk0TB37CuoPqbxdJzlbDqmo50eq3yPee7qakDqcdt62NtPzYrfg2jN7heLPD6AVPszU1Zyvx/nYp/v2x8bP8Eax41squd28KVvtbl4IPE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708631415; c=relaxed/simple; bh=DN/mPR/MulUxISIwqdVAZ+Dv5KqrCmA0c9BnouZcZQI=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=dGvxEd5cYFtv2BFOwEFoR9yDBy/5fGm398a7fM8I2K6Pzq4m4B95xu7YGK50FNZ8hjymplp6hDG0Q0L3AwxK1w9+41Ind2x7Af0O0QVdt9y3hMxjKDVtsxwe4jqYZeklbvKl62wHU6jQTLiqQIiHBJ+XdeqkEdwAHszy/6XsAdk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1BFAC433A6; Thu, 22 Feb 2024 19:50:14 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rdF70-00000006fYj-0CcN; Thu, 22 Feb 2024 14:52:06 -0500 Message-ID: <20240222195205.909016488@goodmis.org> User-Agent: quilt/0.67 Date: Thu, 22 Feb 2024 14:51:13 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= , Rodrigo Vivi , Chuck Lever Subject: [PATCH 2/2] tracing: Do not calculate strlen() twice for __string() fields References: <20240222195111.139824528@goodmis.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Steven Rostedt (Google)" The TRACE_EVENT() macro handles dynamic strings by having: TP_PROTO(struct some_struct *s), TP_ARGS(s), TP_STRUCT__entry( __string(my_string, s->string) ), TP_fast_assign( __assign_str(my_string, s->string); ) TP_printk("%s", __get_str(my_string)) There's even some code that may call a function helper to find the s->string value. The problem with the above is that the work to get the length of s->string is done twice. Once at the __string() and again in the __assign_str(). The length of the string is calculated via a strlen(), not once, but twice (via strcpy() in __assign_str()). Once during the __string() macro and again in __assign_str(). But the length is actually already recorded in the data location and there's no reason to call strlen() again. Just use the saved length that was saved in the __string() code for the __assign_str() code. Signed-off-by: Steven Rostedt (Google) --- include/trace/stages/stage6_event_callback.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/include/trace/stages/stage6_event_callback.h b/include/trace/stages/stage6_event_callback.h index e09e3d019dcc..d389725937e9 100644 --- a/include/trace/stages/stage6_event_callback.h +++ b/include/trace/stages/stage6_event_callback.h @@ -32,8 +32,9 @@ #undef __assign_str #define __assign_str(dst, src) \ - strcpy(__get_str(dst), __data_offsets.dst##_ptr_ ? \ - __data_offsets.dst##_ptr_ : "(null)") + memcpy(__get_str(dst), __data_offsets.dst##_ptr_ ? \ + __data_offsets.dst##_ptr_ : "(null)", \ + __get_dynamic_array_len(dst)) #undef __assign_str_len #define __assign_str_len(dst, src, len) \ @@ -94,8 +95,9 @@ #undef __assign_rel_str #define __assign_rel_str(dst, src) \ - strcpy(__get_rel_str(dst), __data_offsets.dst##_ptr_ ? \ - __data_offsets.dst##_ptr_ : "(null)") + memcpy(__get_rel_str(dst), __data_offsets.dst##_ptr_ ? \ + __data_offsets.dst##_ptr_ : "(null)", \ + __get_rel_dynamic_array_len(dst)) #undef __assign_rel_str_len #define __assign_rel_str_len(dst, src, len) \