On 07/24/2013 05:51 PM, Viresh Kumar wrote:
On 24 July 2013 14:16, Chanwoo Choi cw00.choi@samsung.com wrote:
In case that all CPUs share same cpufreq policy. Each debugfs dentry of CPU[1-3] except for CPU0 has symbolic link to CPU0's debugfs directory as following.
-sh-4.1# ls -al /sys/kernel/debug/cpufreq/ total 0 drwxr-xr-x 3 root root 0 Jan 1 09:00 . drwx------ 28 root root 0 Jan 1 09:00 .. drwxr-xr-x 2 root root 0 Jan 1 09:00 cpu0 (policy->cpu is 0) lrwxrwxrwx 1 root root 0 Jan 1 09:00 cpu1 -> ./cpu0 lrwxrwxrwx 1 root root 0 Jan 1 09:00 cpu2 -> ./cpu0 lrwxrwxrwx 1 root root 0 Jan 1 09:00 cpu3 -> ./cpu0
If turn off CPU0 state, I have to move debugfs directory data from cpu0 to cpu1 and again create link to cpu1's debugfs directory for CPU[2-3] debugfs directory. So, I removed dentry link of CPU[1-3] before creating link again.
cpu1 cpu2 -> ./cpu1 cpu3 -> ./cpu1
But I can rewrite new link of CPU[2-3] to previous dentry link(policy->cpu_debugfs[2] or policy->cpu_debugfs[3]) for reducing unnecessary code without revmoval sequence.
Because we aren't freeing the debugfs node at all (just renaming it), the links might still be good after renaming.. But please check if it is true.
So, according to me you need to do this:
- Remove symlink for new policy->cpu, i..e cpu1 in your example
- rename debugfs entry to give it to cpu1 instead of cpu0.
- Set cpu0 pointer to NULL.
Probably that's it.
And, I add additional step on below:
- Remove symlink for new policy->cpu, i..e cpu1 in your example
- rename debugfs entry to give it to cpu1 instead of cpu0.
- Store renamed cpu0 pointer to cpu1 pointer - Create new link for CPU[2-3] to CPU1's debugfs directory because debugfs use string path to create symbolic link. It isn't automatically connected with new CPU1 debugfs directory.
- Set cpu0 pointer to NULL.
Thanks, Chanwoo Choi