Re: [PATCH] arch: mips: sibyte: Return -EFAULT if copy_to_user() fails

[Maciej W. Rozycki]

On Mon, 1 Mar 2021, Sergei Shtylyov wrote:

> > The copy_to_user() function returns the number of bytes remaining to be
> > copied, but we want to return -EFAULT if the copy doesn't complete.
> 
>    Then 'err' is hardly a good name for that variable. :-)

 Something like `left' might be better, especially as it's the sole use.  
Also it's been like this from the beginning, so:

Fixes: bb9b813bb665 ("[MIPS] Sibyte: Fix ZBbus profiler")

or maybe:

Fixes: d619f38fdacb ("[MIPS] Add bcm1480 ZBus trace support, fix wait related bugs")

(since the file was renamed from a different name with the latter commit) 
would I think be helpful for backports too.  It looks like potentially 
quite a nasty bug to me if someone actually uses this piece (I haven't).

  Maciej