[LTP] [PATCH v4 2/4] zram/zram_lib.sh: adapt the situation that zram device is being used

[Petr Vorel]

> Hi Petr
> > Hi Xu,

> >>>> If zram-generator package is installed and works, then we can not remove zram module
> >>>> because zram swap is being used. This case needs a clean zram environment, change this
> >>>> test by using hot_add/hot_remove interface[1]. So even zram device is being used, we
> >>>> still can add zram device and remove them in cleanup.

> >>> BTW this was added in v4.2-rc1 (6 years ago, 6566d1a32bf7 ("zram: add dynamic
> >>> device add/remove functionality")). Hopefully anybody still supporting older
> >>> kernels is using old LTP for it.
> >> Oh, I don't realize it before. I tested it on centos7 then I think this
> >> control interface maybe introduced long time ago.

> >> To be honst, I don't want to make this case more complex. How about
> >> adding  /sys/class/zram-control check after load zram module. If not,
> >> just report  case needs to use hot_add/hot_remove interface .

> > Would it work something like this?
> I don't want to use kernel version check because the hot_add/hot_remove 
> interface is easy to backport. I will send a v5
> 1) new kernel and not load zram kernel module, then modprobe and rmmod 
> is enough, doesn't need to use hot_add/hot_remove
> 2) new kernel and load zram kernel module or built in kernel, use 
> hot_add/hot_remove
> 3) old kernel and can be modprobe and rmmod, work as 1)
> 4)old kernel but is being used or built in kernel, then skip this case 
> like patch v3 does
Sure, make sense (although you didn't avoid more complexity).
Thanks working on this!

Kind regards,
Petr