should "get_user_pages()" really be phased out?

[Robert P. J. Day]

  poking around mm/gup.c at "get_user_pages()" and related routines,
and noticed this:

 * get_user_pages should be phased out in favor of
 * get_user_pages_locked|unlocked or get_user_pages_fast. Nothing
 * should use get_user_pages because it cannot pass
 * FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.

so does that mean what it seems to mean ... that nothing outside of
memory management should call get_user_pages() directly? i can see
that some of those other routines are implemented in terms of
get_user_pages() -- does that mean that get_user_pages() should be
made static so that only those routines are allowed to call it, and
everyone else should invoke one of the other routines?

  just trying to understand the eventual desired fate of
get_user_pages().

rday

-- 


Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca

Twitter:   http://twitter.com/rpjday
LinkedIn:   http://ca.linkedin.com/in/rpjday



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RE: skb_clone related query

[Jeff Haran]

> -Original Message-
> From: kernelnewbies-boun...@kernelnewbies.org [mailto:kernelnewbies-
> boun...@kernelnewbies.org] On Behalf Of pavi1729
> Sent: Monday, December 28, 2015 6:16 AM
> To: kernelnewbies@kernelnewbies.org
> Subject: skb_clone related query
> 
> Hi,
>   Just out of curisity, I was looking at Kernel 3.14, skb_clone function in
> f_ncm.c
> 
> http://lxr.free-
> electrons.com/source/drivers/usb/gadget/f_ncm.c?v=3.14#L1063
> 
> 
> QUERY : Shouldn't a kfree_skb(skb2); happen before goto err @1070 ?
>   Is this not a memleak ?
> 
> 
> 1068   if (!skb_pull(skb2, index)) {
> 1069 ret = -EOVERFLOW;
> 1070 goto err;
> 1071   }
> 
> 
> Thanks,
> Pavi

Looks like an skb leak to me. Though the fix would need to consider the case 
where skb2 was set equal to skb at line 1061 instead of being cloned.

Jeff Haran


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