Re: [PATCH v4] block: genhd: don't call probe function with major_names_lock held

On Wed, Aug 18, 2021 at 11:34:15PM +0900, Tetsuo Handa wrote:

On 2021/08/18 22:47, Christoph Hellwig wrote:

quoted

Hi Tetsuo,

I might sound like a broken record, but we need to reduce the locking
complexity, not make it worse and fall down the locking cliff.  I did
send a suggested series this morning, in which you found a bunch of
bugs.  I'd appreciate it if you could use your superior skills to
actually help explain the issue and arrive at a common solution that
actually simplifies things instead of steaming down the locking cliff
full speed.  Thank you very much.

I posted "[PATCH] loop: break loop_ctl_mutex into loop_idr_spinlock and loop_removal_mutex"
which reduces the locking complexity while fixing bugs, but you ignored it. Instead,
you decided to remove cryptoloop module (where userspace doing "modprobe cryptoloop"
will break). That is, you decided not to provide patches which can be backported.

Do not ever worry about backporting patches.  Worry about getting the
changes and code correct, stable work can come afterwards, if needed.

thanks,

greg k-h