* Re: [PATCH 2/3] Virtio draft IV: the block driver
[not found] ` <200707050932.50110.borntraeger@de.ibm.com>
@ 2007-07-06 0:33 ` Rusty Russell
0 siblings, 0 replies; only message in thread
From: Rusty Russell @ 2007-07-06 0:33 UTC (permalink / raw)
To: Christian Borntraeger
Cc: virtualization, Andrew Morton, lkml - Kernel Mailing List, Ingo Molnar
On Thu, 2007-07-05 at 09:32 +0200, Christian Borntraeger wrote:
> Am Mittwoch, 4. Juli 2007 schrieb Rusty Russell:
> > + vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
> > + if (!vbr)
> > + goto stop;
> [...]
> > + BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg));
> > + vbr->req = req;
> > + if (!do_req(q, vblk, vbr))
> > + goto stop;
> [...]
> > +stop:
> > + /* Queue full? Wait. */
> > + blk_stop_queue(q);
> > + mempool_free(vbr, vblk->pool);
>
>
> Hmm, can mempool_free really handle NULL as its first argument? (first goto).
Good point. Any objections to fixing that?
Cheers,
Rusty.
===
Christian Borntraeger points out that mempool_free() doesn't noop when
handed NULL. This is inconsistent with the other free-like functions
in the kernel.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff -r a306f0a8de5e mm/mempool.c
--- a/mm/mempool.c Fri Jul 06 10:28:39 2007 +1000
+++ b/mm/mempool.c Fri Jul 06 10:29:40 2007 +1000
@@ -263,6 +263,9 @@ void mempool_free(void *element, mempool
{
unsigned long flags;
+ if (unlikely(element == NULL))
+ return;
+
smp_mb();
if (pool->curr_nr < pool->min_nr) {
spin_lock_irqsave(&pool->lock, flags);
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