Re: [PATCH][RFC/v1][8/12] Add IPoIB (IP-over-InfiniBand) driver

[Roland Dreier <roland@topspin.com>]

    Greg> What's wrong with using the dev_printk() and friends instead
    Greg> of your own?

dev_printk expects a struct device, not a net_device.

    Greg> And why cast a pointer in a macro, don't you know the type
    Greg> of it anyway?

this lets us pass in the return value of netdev_priv() directly
without having to have the cast in the code that uses the macro.

    Greg> You're using a separate filesystem to export debug data?
    Greg> I'm all for new virtual filesystems, but why not just use
    Greg> sysfs for this?  What are you doing in here that you can't
    Greg> do with another mechanism (netlink, sysfs, sockets, relayfs,
    Greg> etc.)?

For each multicast group, we want to export the GID, how long it's
been around, whether our join has completed and whether it's
send-only.  It wouldn't be too bad to create a kobject with all those
attributes but getting the info from so many little files is a little
bit of a pain, and so is dealing with kobject lifetime rules.  It's
even worse with netlink since then a new tool is required.  (AFAIK
relayfs isn't in Linus's kernel).

It's nice to be able to tell someone to just mount ipoib_debugfs and
send the contents of debugfs/ib0_mcg.

The actual filesystem stuff is pretty trivial using everything libfs
provides for us now...

    Greg> Why not just use 2 different debug variables for this?

No real reason... I'll fix it up.

    >> + +int mcast_debug_level;

    Greg> Global?

Good point, I'll move it into ipoib_multicast.c.

 - R.