Re: [PATCH v2] macvtap: rcu_dereference outside read-lock section
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2012-08-12 08:48:39
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On Sun, Aug 12, 2012 at 10:26:31AM +0400, Denis Efremov wrote:
quoted hunk ↗ jump to hunk
rcu_dereference occurs in update section. Replacement by rcu_dereference_protected in order to prevent lockdep complaint. Found by Linux Driver Verification project (linuxtesting.org) Signed-off-by: Denis Efremov <redacted> --- drivers/net/macvtap.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 0737bd4..0f0f9ce 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c@@ -94,7 +94,8 @@ static int get_slot(struct macvlan_dev *vlan, struct macvtap_queue *q) int i; for (i = 0; i < MAX_MACVTAP_QUEUES; i++) { - if (rcu_dereference(vlan->taps[i]) == q) + if (rcu_dereference_protected(vlan->taps[i], + lockdep_is_held(&macvtap_lock)) == q)
And now it's too long. Maybe a temporary would be better? struct macvtap_queue *t; t = rcu_dereference_protected(vlan->taps[i], lockdep_is_held(&macvtap_lock)); if (t == q) return i; ? Anyway - Acked-by: Michael S. Tsirkin <mst@redhat.com>
return i; } -- 1.7.7