From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id 599C7532D for ; Mon, 9 Nov 2015 15:04:10 +0100 (CET) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP; 09 Nov 2015 06:04:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,266,1444719600"; d="scan'208";a="831715002" Received: from irsmsx107.ger.corp.intel.com ([163.33.3.99]) by fmsmga001.fm.intel.com with ESMTP; 09 Nov 2015 06:04:04 -0800 Received: from irsmsx155.ger.corp.intel.com (163.33.192.3) by IRSMSX107.ger.corp.intel.com (163.33.3.99) with Microsoft SMTP Server (TLS) id 14.3.248.2; Mon, 9 Nov 2015 14:02:29 +0000 Received: from irsmsx103.ger.corp.intel.com ([169.254.3.13]) by irsmsx155.ger.corp.intel.com ([169.254.14.150]) with mapi id 14.03.0248.002; Mon, 9 Nov 2015 14:02:29 +0000 From: "Richardson, Bruce" To: Adrien Mazarguil Thread-Topic: [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header Thread-Index: AQHRFi9frvNHb8RAG0uWI1YANX292Z6LEV0AgACYMACAAIp8gIABV3oAgAG0FoCAAANygIAEeJaAgAADEnA= Date: Mon, 9 Nov 2015 14:02:28 +0000 Message-ID: <59AF69C657FD0841A61C55336867B5B03598018B@IRSMSX103.ger.corp.intel.com> References: <1441811374-28984-1-git-send-email-bruce.richardson@intel.com> <1446552059-5446-1-git-send-email-bruce.richardson@intel.com> <1446552059-5446-3-git-send-email-bruce.richardson@intel.com> <4698587.GS9blBozDC@xps13> <20151104102418.GN3518@6wind.com> <20151104103957.4cabd090@xeon-e3> <20151105150918.GV3518@6wind.com> <20151106171007.GB19512@bricha3-MOBL3> <20151106172227.GC19512@bricha3-MOBL3> <20151109133905.GL4013@6wind.com> In-Reply-To: <20151109133905.GL4013@6wind.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.181] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Nov 2015 14:04:11 -0000 > -----Original Message----- > From: Adrien Mazarguil [mailto:adrien.mazarguil@6wind.com] > Sent: Monday, November 9, 2015 1:39 PM > To: Richardson, Bruce > Cc: Stephen Hemminger ; Thomas Monjalon > ; dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros > to header >=20 > On Fri, Nov 06, 2015 at 05:22:27PM +0000, Bruce Richardson wrote: > > On Fri, Nov 06, 2015 at 05:10:07PM +0000, Bruce Richardson wrote: > > > On Thu, Nov 05, 2015 at 04:09:18PM +0100, Adrien Mazarguil wrote: > > > > > > > > I won't argue against this as it's obviously more complex than the > original > > > > method, however note that users of the RTE_PMD_DEBUG_TRACE() macro > do not > > > > have to modify their code. They shouldn't care about the > implementation. > > > > > > > > Also note that we can do much cleaner code if we drop the all macro= s > > > > implementation using a (much easier to debug) static inline > function, > > > > only perhaps with a wrapper macro that provides __LINE__, __func__ > and > > > > __FILE__ as arguments. Nontrival code shouldn't be done in macros > anyway. > > > > > > > Getting something working with __FILE__ and probably __LINE__ would b= e > easy enough > > > with a helper macro, but __func__ is not so easy as it's not a > preprocessor symbol > > > [since the pre-processor has no idea what function you are in]. > > > > > > However, using func, here is the best I've come up with so far. It's > not that > > > pretty, but it's probably easier to work with than the macro version. > > > > > > #ifdef RTE_LIBRTE_ETHDEV_DEBUG > > > -#define RTE_PMD_DEBUG_TRACE(fmt, args...) \ > > > - RTE_LOG(ERR, PMD, "%s: " fmt, __func__, ## args) > > > +#define RTE_PMD_DEBUG_TRACE(...) \ > > > + rte_pmd_debug_trace(__func__, __VA_ARGS__) > > > + > > > +static inline void > > > +rte_pmd_debug_trace(const char *func_name, const char *fmt, ...) > > > +{ > > > + static __thread char buffer[128]; > > > + char *out_buf =3D buffer; > > > + unsigned count; > > > + va_list ap; > > > + > > > + count =3D snprintf(buffer, sizeof(buffer), "%s: %s", func_na= me, > fmt); > > > + if (count >=3D sizeof(buffer)) { // truncated output > > > + char *new_buf =3D malloc(count + 1); > > > + if (new_buf =3D=3D NULL) // no memory, just print 12= 8 > chars > > > + goto print_buffer; > > > + snprintf(new_buf, count + 1, "%s: %s", func_name, > fmt); > > > + va_start(ap, fmt); > > > + rte_vlog(RTE_LOG_ERR, RTE_LOGTYPE_PMD, buffer, ap); > > > + va_end(ap); > > > + free(new_buf); > > > + return; > > > + } > > > + > > > +print_buffer: > > > + va_start(ap, fmt); > > > + rte_vlog(RTE_LOG_ERR, RTE_LOGTYPE_PMD, out_buf, ap); > > > + va_end(ap); > > > +} > > > #else > > > #define RTE_PMD_DEBUG_TRACE(fmt, args...) > > > #endif > > > > > > Comments or improvements? >=20 > Such a function shouldn't malloc() anything. The entire line should fit o= n > the stack (crashing is fine if it does not, then it's probably a bug). We > did something in two passes along these lines in mlx5_defs.h (not pretty > but > quite useful): >=20 > /* Allocate a buffer on the stack and fill it with a printf format > string. */ > #define MKSTR(name, ...) \ > char name[snprintf(NULL, 0, __VA_ARGS__) + 1]; \ > \ > snprintf(name, sizeof(name), __VA_ARGS__) >=20 > Untested but I guess modifying that function accordingly would look like: >=20 > static inline void > rte_pmd_debug_trace(const char *func_name, const char *fmt, ...) > { > va_list ap; > va_start(ap, fmt); >=20 > static __thread char buffer[vsnprintf(NULL, 0, fmt, ap)]; >=20 > va_end(ap); > va_start(ap, fmt); > vsnprintf(buffer, sizeof(buffer), fmt, ap); > va_end(ap); > rte_log(RTE_LOG_ERR, RTE_LOGTYPE_PMD, "%s: %s", func_name, > buffer); > } >=20 Looks a much better option. >>From this, though, I assume then that we are only looking to support the -p= edantic flag in conjuction with c99 mode or above. Supporting -pedantic wit= h the pre-gcc-5 versions won't allow that to work though, as variably sized= arrays only came in with c99, and were gnu extensions before that. Regards, /Bruce