From: Dave Wysochanski <dwysocha@redhat.com>
Date: Fri, 05 Dec 2008 22:27:44 -0500
Subject: [PATCH] Make _init_rand() thread safe - use rand_r() instead of rand().
In-Reply-To: <20081206022653.GF26097@agk.fab.redhat.com>
References: <1228517565-28873-1-git-send-email-dwysocha@redhat.com>
	<20081206022653.GF26097@agk.fab.redhat.com>
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On Sat, 2008-12-06 at 02:26 +0000, Alasdair G Kergon wrote:
> On Fri, Dec 05, 2008 at 05:52:45PM -0500, Dave Wysochanski wrote:
> > This random code is for temp files.  Other code which uses
> > /dev/urandom is used for uuids.  Should we be using /dev/urandom
> > everywhere?
>  
> Well look what we are using it for - we are not relying on the randomness
> - if the filename is already in use, we just try another one - so it's
> nothing to worry about.
> 
> > +	if (!create_temp_name(temp_dir, temp_file, sizeof(temp_file), &fd,
> > +			      &vg->cmd->rand_seed)) {
> 
> Just pass 'cmd'? (as first arg)
> 

I originally did that but then thought it might be better to avoid
polluting lvm-file.c with includes just so I could dereference cmd.

> Does this patch do enough to ensure each thread will get a different value of
> 'seed'?
> 
Probably not.  A better seed might use /dev/urandom or gettimeofday()
with tv_usec granularity.