Hi Keith, On Thu, Aug 04, 2016 at 04:09:08PM -0600, Keith Busch wrote: > We can't initialize the list head on deletion as this causes the node > to point to itself, looping infinitely if the vmd IRQ handler happens > to be servicing that node. > > The list initialization supposed to fix a bug from multiple calls to > disable the same IRQ. We can fix this instead just checking if the > previous pointer indicates it was already deleted. > > Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx> > --- > arch/x86/pci/vmd.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/pci/vmd.c b/arch/x86/pci/vmd.c > index e88b417..2294907 100644 > --- a/arch/x86/pci/vmd.c > +++ b/arch/x86/pci/vmd.c > @@ -136,8 +136,8 @@ static void vmd_irq_disable(struct irq_data *data) > data->chip->irq_mask(data); > > raw_spin_lock_irqsave(&list_lock, flags); > - list_del_rcu(&vmdirq->node); > - INIT_LIST_HEAD_RCU(&vmdirq->node); > + if (vmdirq->node.prev != LIST_POISON2) > + list_del_rcu(&vmdirq->node); It doesn't seem quite right to test for LIST_POISON2. It seems like a little too much knowledge of list internals. There are no other similar tests in the kernel. Surely this isn't the only case where we need to remove from a list that another thread might be traversing. I would look for other similar situations and copy the way they handle it. I think I saw a Fixes: tag later, so I assume you'll pick that up for v2. Should this also be tagged for stable? Are there any bug reports we should reference? > raw_spin_unlock_irqrestore(&list_lock, flags); > } > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
