From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Wed, 10 Apr 2013 17:05:21 +0200 Subject: [PATCH 05/18] cpuidle: make a single register function for all In-Reply-To: <51657E61.9010701@gmail.com> References: <1365603743-5618-1-git-send-email-daniel.lezcano@linaro.org> <1365603743-5618-6-git-send-email-daniel.lezcano@linaro.org> <51657E61.9010701@gmail.com> Message-ID: <51657FB1.6030209@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 04/10/2013 04:59 PM, Rob Herring wrote: > On 04/10/2013 09:22 AM, Daniel Lezcano wrote: >> The usual scheme to initialize a cpuidle driver on a SMP is: >> >> cpuidle_register_driver(drv); >> for_each_possible_cpu(cpu) { >> device = &per_cpu(cpuidle_dev, cpu); >> cpuidle_register_device(device); >> } >> >> This code is duplicated in each cpuidle driver. >> >> On UP systems, it is done this way: >> >> cpuidle_register_driver(drv); >> device = &per_cpu(cpuidle_dev, cpu); >> cpuidle_register_device(device); >> >> On UP, the macro 'for_each_cpu' does one iteration: >> >> #define for_each_cpu(cpu, mask) \ >> for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask) >> >> Hence, the initialization loop is the same for UP than SMP. >> >> Beside, we saw different bugs / mis-initialization / return code unchecked in >> the different drivers, the code is duplicated including bugs. After fixing all >> these ones, it appears the initialization pattern is the same for everyone. >> >> Let's add a wrapper function doing this initialization with a cpumask parameter >> for the coupled idle states and use it for all the drivers. >> >> That will save a lot of LOC, consolidate the code, and the modifications in the >> future could be done in a single place. Another benefit is the consolidation of >> the cpuidle_device variable which is now in the cpuidle framework and no longer >> spread accross the different arch specific drivers. >> >> Signed-off-by: Daniel Lezcano >> --- > > Perhaps my ack was too quick... > >> +int cpuidle_register(struct cpuidle_driver *drv, >> + const struct cpumask *const coupled_cpus) >> +{ >> + int ret, cpu; >> + struct cpuidle_device *device; >> + >> + ret = cpuidle_register_driver(drv); >> + if (ret) { >> + printk(KERN_ERR "failed to register cpuidle driver\n"); >> + return ret; >> + } >> + >> + for_each_possible_cpu(cpu) { >> + device = &per_cpu(cpuidle_dev, cpu); >> + device->cpu = cpu; >> +#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED >> + device->coupled_cpus = *coupled_cpus; > > This needs a NULL check. CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED is most > likely going to be enabled with multi-platform kernels and this will crash. Good point, I will fix it. > Also, I think typically struct copies have a note that it is copy. > > Rob > -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog