On Tue, 2014-04-22 at 16:40 -0400, Tejun Heo wrote: > Hello, > > On Tue, Apr 22, 2014 at 10:29:37AM +0800, Li Zhong wrote: > > The probe/release files are attribute files for cpu subsys, looks like > > following in sysfs dirs > > > > $ cd /sys/devices/system/cpu/ > > $ ls -l > > total 0 > > drwxr-xr-x. 7 root root 0 Apr 17 19:00 cpu0 > > drwxr-xr-x. 4 root root 0 Apr 17 19:00 cpu1 > > drwxr-xr-x. 4 root root 0 Apr 17 19:00 cpu10 > > ...... > > drwxr-xr-x. 3 root root 0 Apr 20 08:00 cpufreq > > drwxr-xr-x. 2 root root 0 Apr 20 08:00 cpuidle > > -rw-------. 1 root root 65536 Apr 21 00:28 dscr_default > > -r--r--r--. 1 root root 65536 Apr 21 00:28 kernel_max > > -r--r--r--. 1 root root 65536 Apr 21 00:28 offline > > -r--r--r--. 1 root root 65536 Sep 4 2014 online > > -r--r--r--. 1 root root 65536 Apr 21 00:28 possible > > drwxr-xr-x. 2 root root 0 Apr 20 08:00 power > > -r--r--r--. 1 root root 65536 Apr 17 20:46 present > > --w-------. 1 root root 65536 Apr 21 00:28 probe <----- > > --w-------. 1 root root 65536 Apr 21 00:28 release <----- > > -rw-------. 1 root root 65536 Apr 21 00:28 subcores_per_core > > -rw-r--r--. 1 root root 65536 Apr 21 00:28 uevent > > > > From the code, it seems cpu subsys won't be unregistered, and it doesn't > > make sense to remove all the cpus in the system. > > I don't think I'm following you. Are you saying that no files which > are protected under the hotplug lock that cpu subsys uses are removed > during offlining?
Sorry, Maybe I didn't say it clearly. There are files under cpu#, e.g. $ cd /sys/devices/system/cpu/cpu0 $ ls cache dscr node1 pmc1 pmc5 smt_snooze_delay uevent cpuidle mmcr0 online pmc2 pmc6 spurr crash_notes mmcr1 physical_id pmc3 power subsystem crash_notes_size mmcra pir pmc4 purr topology If you remove cpu0, then the cpu0 directory will be removed, together with the "online" file in the directory, while some other process might be writing 0 or 1 to it. But here, for the probe/release, take "release" for example, if user writes something that stands for cpu0 to it, the cpu0 will be removed, and the cpu0 directory and the files under it will be removed. But "release" itself is not removed. They are attributes of cpu_subsys, not of some specific cpus. Hopes the above makes things a bit clearer. Thanks, Zhong > > Thanks. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/