From: Declan Doherty <declan.doherty@intel.com>
To: "Richardson, Bruce" <bruce.richardson@intel.com>,
Adrien Mazarguil <adrien.mazarguil@6wind.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header
Date: Tue, 10 Nov 2015 10:31:17 +0000 [thread overview]
Message-ID: <5641C775.5050006@intel.com> (raw)
In-Reply-To: <59AF69C657FD0841A61C55336867B5B03598018B@IRSMSX103.ger.corp.intel.com>
On 09/11/15 14:02, Richardson, Bruce wrote:
>
>
>> -----Original Message-----
>> From: Adrien Mazarguil [mailto:adrien.mazarguil@6wind.com]
>> Sent: Monday, November 9, 2015 1:39 PM
>> To: Richardson, Bruce <bruce.richardson@intel.com>
>> Cc: Stephen Hemminger <stephen@networkplumber.org>; Thomas Monjalon
>> <thomas.monjalon@6wind.com>; dev@dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros
>> to header
>>
>> 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 macros
>>>>> 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 be
>> 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 = buffer;
>>>> + unsigned count;
>>>> + va_list ap;
>>>> +
>>>> + count = snprintf(buffer, sizeof(buffer), "%s: %s", func_name,
>> fmt);
>>>> + if (count >= sizeof(buffer)) { // truncated output
>>>> + char *new_buf = malloc(count + 1);
>>>> + if (new_buf == NULL) // no memory, just print 128
>> 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?
>>
>> Such a function shouldn't malloc() anything. The entire line should fit on
>> 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):
>>
>> /* 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__)
>>
>> Untested but I guess modifying that function accordingly would look like:
>>
>> static inline void
>> rte_pmd_debug_trace(const char *func_name, const char *fmt, ...)
>> {
>> va_list ap;
>> va_start(ap, fmt);
>>
>> static __thread char buffer[vsnprintf(NULL, 0, fmt, ap)];
>>
>> 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);
>> }
>>
>
> Looks a much better option.
>
> From this, though, I assume then that we are only looking to support the -pedantic flag in conjuction with c99 mode or above. Supporting -pedantic with 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
>
I had made some similar changes in the cryptodev patch set to allow
these macros to be shared between the ethdev and cryptodev, but I wasn't
aware of the -pedantic build issues. I've incorporate the changes from
patch 1 & 2 discussed here into the cryptodev patch set. See patch 2/10
(http://dpdk.org/ml/archives/dev/2015-November/027888.html) for the
implementation of the rte_pmf_debug_trace function. Any comments or
ack's are welcome :)
Declan
next prev parent reply other threads:[~2015-11-10 10:26 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-12 11:28 [dpdk-dev] [PATCH 0/4] ethdev: Add checks for function support in driver Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 1/4] ethdev: rename macros to have RTE_ETH prefix Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 2/4] ethdev: move RTE_ETH_FPTR_OR_ERR macros to header Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 3/4] ethdev: remove duplicated debug functions Bruce Richardson
2015-06-12 11:28 ` [dpdk-dev] [PATCH 4/4] ethdev: check support for rx_queue_count and descriptor_done fns Bruce Richardson
2015-06-12 17:32 ` Roger B. Melton
2015-06-15 10:14 ` Bruce Richardson
2015-07-06 15:11 ` Thomas Monjalon
2015-07-26 20:44 ` Thomas Monjalon
2015-09-09 15:09 ` [dpdk-dev] [PATCH v2 0/4] ethdev: minor cleanup Bruce Richardson
2015-09-09 15:09 ` [dpdk-dev] [PATCH v2 1/4] ethdev: rename macros to have RTE_ETH prefix Bruce Richardson
2015-09-09 15:09 ` [dpdk-dev] [PATCH v2 2/4] ethdev: move error checking macros to header Bruce Richardson
2015-09-09 15:09 ` [dpdk-dev] [PATCH v2 3/4] ethdev: remove duplicated debug functions Bruce Richardson
2015-09-09 15:09 ` [dpdk-dev] [PATCH v2 4/4] ethdev: check driver support for functions Bruce Richardson
2015-09-28 10:23 ` [dpdk-dev] [PATCH v2 0/4] ethdev: minor cleanup Bruce Richardson
2015-11-03 1:11 ` Thomas Monjalon
2015-11-03 10:06 ` Bruce Richardson
2015-11-03 12:00 ` [dpdk-dev] [PATCH v3 " Bruce Richardson
2015-11-03 12:00 ` [dpdk-dev] [PATCH v3 1/4] ethdev: rename macros to have RTE_ETH prefix Bruce Richardson
2015-11-03 12:00 ` [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header Bruce Richardson
2015-11-04 1:19 ` Thomas Monjalon
2015-11-04 10:24 ` Adrien Mazarguil
2015-11-04 14:10 ` Bruce Richardson
2015-11-04 15:25 ` Adrien Mazarguil
2015-11-04 18:39 ` Stephen Hemminger
2015-11-05 15:09 ` Adrien Mazarguil
2015-11-05 15:17 ` Bruce Richardson
2015-11-06 11:49 ` Bruce Richardson
2015-11-06 17:10 ` Bruce Richardson
2015-11-06 17:22 ` Bruce Richardson
2015-11-09 13:39 ` Adrien Mazarguil
2015-11-09 13:50 ` Adrien Mazarguil
2015-11-09 14:02 ` Richardson, Bruce
2015-11-10 10:31 ` Declan Doherty [this message]
2015-11-10 16:08 ` Adrien Mazarguil
2015-11-10 16:21 ` Richardson, Bruce
2015-11-10 17:12 ` Adrien Mazarguil
2015-11-11 10:51 ` Bruce Richardson
2015-11-03 12:00 ` [dpdk-dev] [PATCH v3 3/4] ethdev: remove duplicated debug functions Bruce Richardson
2015-11-03 12:00 ` [dpdk-dev] [PATCH v3 4/4] ethdev: check driver support for functions Bruce Richardson
2015-11-03 22:00 ` Stephen Hemminger
2015-11-04 14:15 ` Bruce Richardson
2015-11-17 12:21 ` [dpdk-dev] [PATCH v4 0/2] ethdev: debug code cleanup Bruce Richardson
2015-11-17 12:21 ` [dpdk-dev] [PATCH v4 1/2] ethdev: remove duplicated debug functions Bruce Richardson
2015-11-17 12:21 ` [dpdk-dev] [PATCH v4 2/2] ethdev: add sanity checks to functions Bruce Richardson
2015-11-17 15:53 ` Stephen Hemminger
2015-11-24 14:56 ` Bruce Richardson
2015-11-24 15:29 ` Thomas Monjalon
2015-11-24 15:45 ` Bruce Richardson
2015-11-24 15:48 ` Thomas Monjalon
2015-11-24 17:37 ` [dpdk-dev] [PATCH v5 0/2] ethdev: debug code cleanup Bruce Richardson
2015-11-24 17:37 ` [dpdk-dev] [PATCH v5 1/2] ethdev: remove duplicated debug functions Bruce Richardson
2015-11-25 18:14 ` Thomas Monjalon
2015-11-24 17:37 ` [dpdk-dev] [PATCH v5 2/2] ethdev: add sanity checks to functions Bruce Richardson
2015-11-25 18:21 ` [dpdk-dev] [PATCH v5 0/2] ethdev: debug code cleanup Thomas Monjalon
2015-11-06 11:52 [dpdk-dev] [PATCH v3 2/4] ethdev: move error checking macros to header Bruce Richardson
2015-11-06 12:25 ` Adrien Mazarguil
2015-11-06 14:39 ` Richardson, Bruce
2015-11-06 14:54 ` Adrien Mazarguil
2015-11-06 15:30 ` Richardson, Bruce
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