Re: [linux-usb-devel] [PATCH 7/9] USB usbfs: destroy submitted urbs only on the disconnected interface

[Duncan Sands]

> > Hi Oliver, I thought you meant that CONFIG_EMBEDDED made WARN_ON go away
> > (or something like that).  If you just mean that it is easy to redefine
> > WARN_ON by hand, then all I can say is: it is also easy to redefine warn
> > by hand!  Anyway, I made you the following patch:
>
> Yes, but I don't trust gcc to optimise away the 'if' if you redefine
> warn().

The "if" cannot be optimized away for the case in point, because it
does something (clears the bit) if it passes the test.  If I used WARN_ON
then it would have to be WARN_ON(1) in the else branch of the if.

> But there is another point. The embedded people deserve a single switch
> to remove assertion checks. The purpose of macros like WARN_ON() is
> easy and _central_ choice of debugging output vs. kernel size.

This is not an argument against using USB's warn, it is an argument for
building warn on top of a centralized macro like WARN_ON or a friend.

All the best,

Duncan.
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