From mboxrd@z Thu Jan 1 00:00:00 1970 From: s.hauer@pengutronix.de (Sascha Hauer) Date: Wed, 2 May 2012 22:21:01 +0200 Subject: [PATCH v2 1/3] ARM: imx: Add common imx cpuidle init functionality. In-Reply-To: References: <1335924760-796-1-git-send-email-rob.lee@linaro.org> <1335924760-796-2-git-send-email-rob.lee@linaro.org> <20120502072701.GR4141@pengutronix.de> Message-ID: <20120502202101.GA16535@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, May 02, 2012 at 02:16:36PM -0500, Rob Lee wrote: > Sascha, > > >> +int __init imx_cpuidle_init(struct cpuidle_driver *drv) > >> +{ > >> + ? ? struct cpuidle_device *dev; > >> + ? ? int cpu_id, ret; > >> + > >> + ? ? if (!drv || drv->state_count > CPUIDLE_STATE_MAX) { > > > > Please don't check for !drv here. When someone calls this function with > > a NULL pointer he should get a nive stack trace allowing him to figure > > out what went wrong. > > > > Ok, I will change this in v3. Given your statement, my understanding > is that I should avoid adding checks to make sure a valid driver > object was given as the stack trace information is all the handling > that is needed. If there is any further logic needed in that rule, > could you elaborate so that I don't make this mistake in the future, > or so that I don't add a check on a driver object in a case that I > should? Here we have the case that only a Kernel developer will add a call to this function. For a kernel developer a stack trace is more useful than a pr_err. Of course this is different when not testing for a NULL pointer causes subtle bugs in unrelated code. > > > > You should only unregister the cpuidle devices you successfully > > registered. Unregistering not yet registered cpuidle devices probably > > has unwanted side effects. > > > > I did not add in this handling because the cpuidle_unregister_device() > call already has a "registered" check so extra handling seemed > unnecessary. But if you still think it is needed just let me know. > It's ok then. I didn't check cpuidle_unregister_device. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |