Re: BUG in shared_policy_replace() ?

[Hugh Dickins <hugh@veritas.com>]

On Tue, 18 Jan 2005, Steve Longerbeam wrote:
> 
> Why free the shared policy created to split up an old
> policy that spans the whole new range? Ie, see patch.

I think you're misreading it.  That code comes from when I changed it
over from sp->sem to sp->lock.  If it finds that it needs to split an
existing range, so needs to allocate a new2, then it has to drop and
reacquire the spinlock around that.  It's conceivable that a racing
task could change the tree while the spinlock is dropped, in such a
way that this split is no longer necessary once we reacquire the
spinlock.  The code you're looking at frees up new2 in that case;
whereas in the normal case, where it is still needed, there's a
new2 = NULL after inserting it, so that it won't be freed below.

Hugh

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