Re: Libxenstore memory leak on static compile

[Roger Pau Monne <roger.pau@citrix.com>]

Ian Campbell wrote:
> On Wed, 2012-09-12 at 14:44 +0100, Andres Lagar-Cavilla wrote:
>> When statically compiling libxenstore.a, the USE_PTHREAD define is not
>> applied. This results in cleanup_{pus/pop} being no-ops. cleanup_p*
>> are used throughout xs.c:read_message to free malloc'ed objects.
>>
>> In short, libxenstore.a will leak memory when reading xenstore
>> messages. OOM killer awaits.
>>
>> This could be solved by either turning on USE_PTHREAD for .a
>> compilation (which, N.B. will not actually link libpthread but instead
>> produce an object archive that needs to be eventually linked to
>> libpthread.so), or by replacing cleanup_p* by proper free calls.
> 
> The reason for the non-pthreads static library was so that you could
> build tiny statically linked xenstore clients against tiny libcs (like
> uclibc) to have things small enough to fit in e.g. your installer initrd
> or in your "guest tools" package.
> 
> It used to be that uclibc didn't have a pthreads library.  Maybe this
> has changed though (Roger, CCd, would know).

Yes, uclibc added a pthread library back in 2002:

http://mailman.uclinux.org/pipermail/uclinux-dev/2002-March/007613.html

> We don't seem to use pthread_cleanup_push/pop very extensively, so I
> think using proper free calls is probably the way to go?
> 
> Using that pthread facility as a cheap and nasty GC seems a bit wrong to
> me anyhow.
> 
> Ian.
>