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[109.190.92.136]) by mx.google.com with ESMTPSA id kv6sm11402263wjb.9.2014.11.27.08.32.53 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Nov 2014 08:32:54 -0800 (PST) From: Thomas Monjalon To: "Wiles, Roger Keith" Date: Thu, 27 Nov 2014 17:32:32 +0100 Message-ID: <4973216.sSJ7srTIKP@xps13> Organization: 6WIND User-Agent: KMail/4.14.3 (Linux/3.17.4-1-ARCH; KDE/4.14.3; x86_64; ; ) In-Reply-To: <20141002113720.GA4900@hmsreliant.think-freely.org> References: <2861812.mN4X60CA8c@xps13> <20141002113720.GA4900@hmsreliant.think-freely.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH v2] rte_mempool_dump() crashes with NULL rte_mempool pointer. 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: Thu, 27 Nov 2014 16:32:55 -0000 2014-10-02 07:37, Neil Horman: > On Thu, Oct 02, 2014 at 09:47:19AM +0200, Thomas Monjalon wrote: > > 2014-10-01 17:05, Bruce Richardson: > > > On Wed, Oct 01, 2014 at 12:01:10PM -0400, Neil Horman wrote: > > > > On Wed, Oct 01, 2014 at 04:43:10PM +0100, Bruce Richardson wrote: > > > > > On Wed, Oct 01, 2014 at 11:02:27AM -0400, Neil Horman wrote: > > > > > > On Wed, Oct 01, 2014 at 03:36:45PM +0200, Thomas Monjalon wrote: > > > > > > > 2014-09-28 08:27, Neil Horman: > > > > > > > > On Sun, Sep 28, 2014 at 05:28:44AM +0000, Wiles, Roger Keith wrote: > > > > > > > > > Check the FILE *f and rte_mempool *mp pointers for NULL and > > > > > > > > > return plus print out a message if RTE_LIBRTE_MEMPOOL_DEBUG is enabled. > > > > > > > > > > > > > > > > > > Signed-off-by: Keith Wiles > > > > > > > > > > > > > > > > I'm fine with this, as I think passing in a NULL mempool is clearly a bug here, > > > > > > > > thats worth panicing over, though I wouldnt mind if we did a RTE_VERIFY_WARN > > > > > > > > macro here instead using what I suggested in my other note > > > > > > > > > > > > > > Passing a NULL mempool to rte_mempool_dump() is a bug in the application. > > > > > > > If you look elsewhere in the DPDK code, you'll see that it's not common to do > > > > > > > such check on input parameters. > > > > > > > A similar discussion already happened few months ago: > > > > > > > http://dpdk.org/ml/archives/dev/2014-June/003900.html > > > > > > > > > > > > > Not sure what your point is here Thomas. I think we're all in agreement that > > > > > > NULL is a bad value to pass in here. Are you asserting that we shouldn't bother > > > > > > with a NULL check at all and just accept the crash as it is? > > > > > > > > > > > > > > > > In the general case: > > > > > * Code in the datapath should not have things like NULL checks > > > > > * However, datapath code should generally have a debug option which turns > > > > > these checks on to help debugging if needed. > > > > > * Code not in the datapath probably should have these checks. > > > > > > > > > Ok, I can understand that, but I would hope that rte_mempool_dump isn't in the > > > > datapath, its rather by definition a debug function, isn't it? > > > > Neil > > > > > > Yes, agreed. [So it probably should have the NULL check]. > > > > I have many arguments to not do this check: > > 1) If it was a coding rule to do this kind of check, it should be done in > > almost every functions. > Only if NULL is an invalid value, and we spot check for NULL all the time (see > eal_parse_coremask as an example from a quick search). > > > 2) It's quite common to not do this check, e.g. what happen with memcpy(NULL,NULL)? > Its also quite common to do the check. I think this is more about if it makes > sense to do it here (i.e. is it a common error to pass a NULL pointer into > mempool_dump?). If so, an extra check with its own specific panic might be > nice. > > > 3) Why check only NULL value? 1 and 2 are also some invalid values... > > > Because NULL is the common case. > Neil Argumentation accepted and patch applied. -- Thomas