Re: [PATCH RESEND net-next 0/5] WWAN debugfs tweaks

On Sun, Nov 28, 2021 at 03:55:17PM +0300, Sergey Ryazanov wrote:

Resend with proper target tree. Also I should mention that the series is
mostly compile-tested since I do not have IOSM supported device, so it
needs Ack from the IOSM developers.

This is a follow-up series to just applied IOSM (and WWAN) debugfs
interface support [1]. The series has two main goals:
1. move the driver-specific debugfs knobs to a subdirectory;
2. make the debugfs interface optional for both IOSM and for the WWAN
   core.

As for the first part, I must say that it was my mistake. I suggested to
place debugfs entries under a common per WWAN device directory. But I
missed the driver subdirectory in the example, so it become:

/sys/kernel/debugfs/wwan/wwan0/trace

Since the traces collection is a driver-specific feature, it is better
to keep it under the driver-specific subdirectory:

/sys/kernel/debugfs/wwan/wwan0/iosm/trace

It is desirable to be able to entirely disable the debugfs interface. It
can be disabled for several reasons, including security and consumed
storage space.

When such needs arise, the disable is done with CONFIG_DEBUGFS knob and
not with per-subsystem configs.

I personally see your CONFIG_*_DEBUGFS patches as a mistake, which
complicates code without any gain at all. Even an opposite is true,
by adding more knobs, you can find yourself with the system which
has CONFIG_DEBUGFS enabled but with your CONFIG_*_DEBUGFS disabled.

Thanks