From mboxrd@z Thu Jan 1 00:00:00 1970 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 22CE214276; Fri, 15 Mar 2024 20:34:55 +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=1710534896; cv=none; b=a94iZ+CgUldr6Ah9yC8UqcNZ1vCaNKJXA9Y7jK9lVwh55NF4Njy2otU2X9TJNIiJuCD8FNITyJxJRWS34glRZgWSBELQwqhGraPsMn23zaPE90BMm/qfQNI5A8gBNRY9qEgWt/GM2A0/KBVG63MwpdXABLWZv/h2Kerwrz5wqsw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710534896; c=relaxed/simple; bh=rh2iM9s2togfh5y0cSe3SpL6yIxMRvA4Gyyt4FOwUMI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DlBNYPOjs9kk1alW8Q1ekh3krZktlIWHWzbjnb4FxYlHvPXrl5kW66JB3DNjZt0RZ+25HEc1x553+B5ccEcBcN83yfQ/Mtn5DZy17QgmMx5ZOss5mMvecVAOErMdA9vbWCFmuXiCqiRAYH2zEx5U7JancaUHO6o5x9oR3tWLe3c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HODH+jWW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HODH+jWW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48292C43390; Fri, 15 Mar 2024 20:34:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710534895; bh=rh2iM9s2togfh5y0cSe3SpL6yIxMRvA4Gyyt4FOwUMI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HODH+jWWdk34xiEmT+fzoojQWvB+c/Lzx4QEVJnabiBRQHWgmWJM2LtLfbwsE/4TA BrxnRh4KEVRC/OJZko4ulsRrgsgYPoNnin5lR7S9lbMA7HE/fwABQqaBXteUGgUBOW mvGUvYsINIcLhKVVrRy+J9Ik4IEaVzYLFbUplJCpeC/xTFRn37I67F0uQp5IrEoGEU ByPaehaGCnFoLTdK45gx2+i/hsKJwXBC/HkqQ5UTbz8Ckky92iPBZzceVygXgx+z5p srOwc74gz2C+5w/vkRYJnwUOkSpcc0/vvtiUsXF3v3zAOn80gav1zf/SnmueIY1jiT 02m5lGBaws6GQ== Date: Fri, 15 Mar 2024 17:34:52 -0300 From: Arnaldo Carvalho de Melo To: Chaitanya S Prakash Cc: Ian Rogers , linux-perf-users@vger.kernel.org, anshuman.khandual@arm.com, Linux Kernel Mailing List Subject: Re: [PATCH 2/3] perf tools: Only treat files as map files when they have the extension .map Message-ID: References: <20240220042957.2022391-1-ChaitanyaS.Prakash@arm.com> <20240220042957.2022391-3-ChaitanyaS.Prakash@arm.com> <0fa391c6-fd9e-42fe-b535-17e7725280e5@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0fa391c6-fd9e-42fe-b535-17e7725280e5@arm.com> On Fri, Feb 23, 2024 at 05:40:02PM +0530, Chaitanya S Prakash wrote: > I'll make the changes, thanks for the review. Have you submitted a new series? Thanks, - Arnaldo > On 2/21/24 20:28, Arnaldo Carvalho de Melo wrote: > > On Tue, Feb 20, 2024 at 06:40:47AM -0800, Ian Rogers wrote: > > > On Mon, Feb 19, 2024 at 8:30 PM Chaitanya S Prakash wrote: > > > > +++ b/tools/perf/util/string2.h > > > > @@ -40,5 +40,6 @@ char *strdup_esc(const char *str); > > > > > > > > unsigned int hex(char c); > > > > char *strreplace_chars(char needle, const char *haystack, const char *replace); > > > > +const char *ends_with(const char *str, const char *suffix); > > > nit: string2.h is an extension of linux's string.h. The tools copy of > > > that is missing functions in the kernel version: > > > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/include/linux/string.h?h=perf-tools-next > > > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/include/linux/string.h?h=perf-tools-next#n398 > > > specifically str_has_prefix. > > > > > > The naming ends_with makes sense but there is also strstarts and > > > str_has_prefix, perhaps str_has_suffix would be the most consistent > > > and intention revealing name? > > > > > > Also, we have strtailcmp which behaves like a reverse strcmp that > > > doesn't compare the lengths of the strings. It seems all uses of > > > strtailcmp are just for a "str_has_suffix". It would make sense to me > > > to remove that function and switch to a common str_has_suffix function > > > which I think is a more intention revealing way of naming what the > > > code is doing. > > So far in perf we try to just reuse whatever function the kernel has for > > the purpose at hand, right now the kernel has: > > > > /** > > * strstarts - does @str start with @prefix? > > * @str: string to examine > > * @prefix: prefix to look for. > > */ > > static inline bool strstarts(const char *str, const char *prefix) > > { > > return strncmp(str, prefix, strlen(prefix)) == 0; > > } > > > > And: > > > > /** > > * str_has_prefix - Test if a string has a given prefix > > * @str: The string to test > > * @prefix: The string to see if @str starts with > > * > > * A common way to test a prefix of a string is to do: > > * strncmp(str, prefix, sizeof(prefix) - 1) > > * > > * But this can lead to bugs due to typos, or if prefix is a pointer > > * and not a constant. Instead use str_has_prefix(). > > * > > * Returns: > > * * strlen(@prefix) if @str starts with @prefix > > * * 0 if @str does not start with @prefix > > */ > > static __always_inline size_t str_has_prefix(const char *str, const char *prefix) > > { > > size_t len = strlen(prefix); > > return strncmp(str, prefix, len) == 0 ? len : 0; > > } > > > > The later seems to give more bang for the buck, so to say, returning the > > prefix lenght. > > > > It is a new addition: > > > > 72921427d46bf9731 (Steven Rostedt (VMware) 2018-12-21 18:10:14 -0500 398) static __always_inline size_t str_has_prefix(const char *str, const char *prefix) > > > > While: > > > > 66f92cf9d415e96a5 (Rusty Russell 2009-03-31 13:05:36 -0600 249) * strstarts - does @str start with @prefix? > > > > ⬢[acme@toolbox linux]$ git grep str_has_prefix| wc -l > > 94 > > ⬢[acme@toolbox linux]$ git grep strstarts| wc -l > > 177 > > ⬢[acme@toolbox linux]$ > > > > Some places use it: > > > > kernel/printk/printk.c: len = str_has_prefix(str, "on"); > > kernel/printk/printk.c: len = str_has_prefix(str, "off"); > > kernel/printk/printk.c: len = str_has_prefix(str, "ratelimit"); > > > > > > static int __control_devkmsg(char *str) > > { > > size_t len; > > > > if (!str) > > return -EINVAL; > > > > len = str_has_prefix(str, "on"); > > if (len) { > > devkmsg_log = DEVKMSG_LOG_MASK_ON; > > return len; > > } > > > > len = str_has_prefix(str, "off"); > > if (len) { > > devkmsg_log = DEVKMSG_LOG_MASK_OFF; > > return len; > > } > > > > len = str_has_prefix(str, "ratelimit"); > > if (len) { > > devkmsg_log = DEVKMSG_LOG_MASK_DEFAULT; > > return len; > > } > > > > return -EINVAL; > > } > > > > > > err = __control_devkmsg(devkmsg_log_str); > > /* > > * Do not accept an unknown string OR a known string with > > * trailing crap... > > */ > > if (err < 0 || (err + 1 != *lenp)) { > > > > /* ... and restore old setting. */ > > devkmsg_log = old; > > strncpy(devkmsg_log_str, old_str, DEVKMSG_STR_MAX_SIZE); > > > > return -EINVAL; > > } > > > > > > So yeah, I agree with Ian that it is more intention revealing, has this > > bonus of returning the strlen for the above use cases, is in the kernel > > sources, so I'm in favour of grabbing a copy of it and replacing the > > strstarts() usage with it, drop strstarts(), then also introduce > > str_has_suffix(), the kernel will get it when it needs, possibly from > > tools/lib/ :-) > > > > - Arnaldo