From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id +EXOIitUpmDWVgAAWB0awg (envelope-from ) for ; Thu, 20 May 2021 08:20:59 -0400 Received: by simark.ca (Postfix, from userid 112) id 8194F1F11C; Thu, 20 May 2021 08:20:59 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_REPLYTO_END_DIGIT,MAILING_LIST_MULTI, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Received: from lists.lttng.org (lists.lttng.org [167.114.26.123]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id D87DA1E54D for ; Thu, 20 May 2021 08:20:58 -0400 (EDT) Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4Fm83G2qWqz1rFh; Thu, 20 May 2021 08:20:58 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1621513258; bh=sYzQKi+6dkpDcpwOyHXwLoFSs1JfEho9MCg/rDr+240=; h=References:In-Reply-To:Date:To:Cc:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=t/yi/SYuStDwycI63zmgnKi3L4Xb7xzYItHTX+zYDwnIKFcwmbUHKtI5OhxIcpXeA rsRkzPSnv4Ipt51SgfP9vJEpHSVv9Z50ENqeyJKm+5n9+unz3Y6ui/AnINkHDCt8OJ Tf5+plqKZ0+GEnQq38VrFJOQZudAVWiNNjwO6mn0Wd8HW0D0V6lXa3Bn6Cxb2eSLWC rFN9pwiIp9vhVgeeAn/DA39ZQjFTP0ESLfUnK/OoirBjy1A1fnhn8FpA6yrpn4nPKC 4GUUYnVyvhJn9BMbVI1BYZvAu0t2lohJTRmVl7yFLMIHZwhO2TYbYoqUvYrFknxQGQ YACynB1143tNg== Received: from mail-oi1-x235.google.com (mail-oi1-x235.google.com [IPv6:2607:f8b0:4864:20::235]) by lists.lttng.org (Postfix) with ESMTPS id 4Fm83F4PqPz1rJP for ; Thu, 20 May 2021 08:20:57 -0400 (EDT) Received: by mail-oi1-x235.google.com with SMTP id c196so8007852oib.9 for ; Thu, 20 May 2021 05:20:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=B8zrmsYFe1n75kQjFWWRjkkLZ6NzgYWsnfDx1B88/p4=; b=Wbdl6S3sUyySk6FCWlfmvflzKORNQJUofJ2HZmMh6zKXsi+1WNQSu2IKTVY2geURfV OVRm6Nkl7qSr/9znTlBCNZftW7vECXhUqWiUUBGHnojm4TrNISAaNdeK/7a+Yd62jk1S mTPJLcdUvMEg1HK+obJiRI3HrFtKlc+9TOeJ7bjeZwBjT8IN1io4mkmZ1JMAiLd5S9A1 PKA6xKPKzBGCQ2bWoSGYMK7F/MGsKz84UkIM5fm4i87/7EGsoUNiQDF2EZvEXmxCIh40 goTYJiyGwbs8NBxlNJUTbVxg4OoLZBqC5mJa5GYnQK14cuCwNiCx0VAHdwx7JOxlEwry vobA== X-Gm-Message-State: AOAM530C/Kk2HKkBPDp+hcsw8odya+iRvruvAufD9zEF+eX9lpRGiSPk iX/R8Ka0zYxX86q2ojPFaQjqXJWz63lFVRJCti8= X-Google-Smtp-Source: ABdhPJwrhtpzT6el0aZE/KfhIvab39b2c3YR6cVj4q3sUEbELd4mv/SjLtY3gTeuJGDutmm7v4u3deZG8FYMLnWBl5s= X-Received: by 2002:aca:acc7:: with SMTP id v190mr3133041oie.28.1621513256899; Thu, 20 May 2021 05:20:56 -0700 (PDT) MIME-Version: 1.0 References: <20210519165648.792939-1-nolange79@gmail.com> <1498635684.51674.1621450841774.JavaMail.zimbra@efficios.com> In-Reply-To: <1498635684.51674.1621450841774.JavaMail.zimbra@efficios.com> Date: Thu, 20 May 2021 14:20:46 +0200 Message-ID: To: Mathieu Desnoyers Cc: lttng-dev Subject: Re: [lttng-dev] [PATCH] Avoid using the heap for small strings with tracef/tracelog X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Norbert Lange via lttng-dev Reply-To: Norbert Lange Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" Am Mi., 19. Mai 2021 um 21:00 Uhr schrieb Mathieu Desnoyers : > > ----- On May 19, 2021, at 12:56 PM, lttng-dev lttng-dev@lists.lttng.org wrote: > > > Try to use vsnprintf with a 512 Byte buffer on the Stack, > > if that fails allocate a larger one. > > I agree with the approach. > > Can we move the hardcoded "512" to a #define within src/common/tracer.h ? > > Thanks, > > Mathieu > > > > > Signed-off-by: Norbert Lange > > --- > > liblttng-ust/tracef.c | 13 ++++++++++--- > > liblttng-ust/tracelog.c | 12 +++++++++--- > > 2 files changed, 19 insertions(+), 6 deletions(-) > > > > diff --git a/liblttng-ust/tracef.c b/liblttng-ust/tracef.c > > index ea98e43e..18c29e25 100644 > > --- a/liblttng-ust/tracef.c > > +++ b/liblttng-ust/tracef.c > > @@ -32,17 +32,24 @@ > > void _lttng_ust_tracef(const char *fmt, ...) > > { > > va_list ap; > > - char *msg; > > + char local_buf[512]; > > + char *msg = local_buf; > > int len; > > > > va_start(ap, fmt); > > - len = vasprintf(&msg, fmt, ap); > > + len = vsnprintf(local_buf, sizeof(local_buf), fmt, ap); > > + if (len >= sizeof(local_buf)) { > > + msg = (char *)malloc(len + 1); > > + len = msg ? vsnprintf(msg, len + 1, fmt, ap) : -1; > > + } > > + > > /* len does not include the final \0 */ > > if (len < 0) > > goto end; > > __tracepoint_cb_lttng_ust_tracef___event(msg, len, > > LTTNG_UST_CALLER_IP()); > > - free(msg); > > end: > > + if (msg != local_buf) > > + free(msg); > > va_end(ap); > > } > > diff --git a/liblttng-ust/tracelog.c b/liblttng-ust/tracelog.c > > index 65fc87ed..a5d110fa 100644 > > --- a/liblttng-ust/tracelog.c > > +++ b/liblttng-ust/tracelog.c > > @@ -35,19 +35,25 @@ > > const char *fmt, ...) \ > > { \ > > va_list ap; \ > > - char *msg; \ > > + char local_buf[512]; \ > > + char *msg = local_buf; \ > > int len; \ > > \ > > va_start(ap, fmt); \ > > - len = vasprintf(&msg, fmt, ap); \ > > + len = vsnprintf(local_buf, sizeof(local_buf), fmt, ap); \ > > + if (len >= sizeof(local_buf)) { \ > > + msg = (char *)malloc(len + 1); \ > > + len = msg ? vsnprintf(msg, len + 1, fmt, ap) : -1; \ > > + } \ > > /* len does not include the final \0 */ \ > > if (len < 0) \ > > goto end; \ > > __tracepoint_cb_lttng_ust_tracelog___##level(file, \ > > line, func, msg, len, \ > > LTTNG_UST_CALLER_IP()); \ > > - free(msg); \ > > end: \ > > + if (msg != local_buf) \ > > + free(msg); \ > > va_end(ap); \ > > } > > > > -- > > 2.30.2 > > > > _______________________________________________ > > lttng-dev mailing list > > lttng-dev@lists.lttng.org > > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com This patch was intended for 2.12, no src/common/tracer.h there. Also this patch is brocken, as a va_list cant be iterated twice. _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev