| Message ID | 20210202070938.7863-1-jgross@suse.com |
|---|---|
| State | New |
| Headers | show |
| Series | xen/netback: avoid race in xenvif_rx_ring_slots_available() | expand |
On 02/02/2021 07:09, Juergen Gross wrote: > Since commit 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") > xenvif_rx_ring_slots_available() is no longer called only from the rx > queue kernel thread, so it needs to access the rx queue with the > associated queue held. > > Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com> > Fixes: 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") > Cc: stable@vger.kernel.org > Signed-off-by: Juergen Gross <jgross@suse.com> Appreciate a quick fix! Is this the only place that sort of race could happen now? Igor
On Tue, 2 Feb 2021 08:09:38 +0100 Juergen Gross wrote: > Since commit 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") > xenvif_rx_ring_slots_available() is no longer called only from the rx > queue kernel thread, so it needs to access the rx queue with the > associated queue held. > > Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com> > Fixes: 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") > Cc: stable@vger.kernel.org > Signed-off-by: Juergen Gross <jgross@suse.com> Should we route this change via networking trees? I see the bug did not go through networking :)
On 04.02.21 00:48, Jakub Kicinski wrote: > On Tue, 2 Feb 2021 08:09:38 +0100 Juergen Gross wrote: >> Since commit 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") >> xenvif_rx_ring_slots_available() is no longer called only from the rx >> queue kernel thread, so it needs to access the rx queue with the >> associated queue held. >> >> Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com> >> Fixes: 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") >> Cc: stable@vger.kernel.org >> Signed-off-by: Juergen Gross <jgross@suse.com> > > Should we route this change via networking trees? I see the bug did not > go through networking :) > I'm fine with either networking or the Xen tree. It should be included in 5.11, though. So if you are willing to take it, please do so. Juergen
diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c index b8febe1d1bfd..accc991d153f 100644 --- a/drivers/net/xen-netback/rx.c +++ b/drivers/net/xen-netback/rx.c @@ -38,10 +38,15 @@ static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue) RING_IDX prod, cons; struct sk_buff *skb; int needed; + unsigned long flags; + + spin_lock_irqsave(&queue->rx_queue.lock, flags); skb = skb_peek(&queue->rx_queue); - if (!skb) + if (!skb) { + spin_unlock_irqrestore(&queue->rx_queue.lock, flags); return false; + } needed = DIV_ROUND_UP(skb->len, XEN_PAGE_SIZE); if (skb_is_gso(skb)) @@ -49,6 +54,8 @@ static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue) if (skb->sw_hash) needed++; + spin_unlock_irqrestore(&queue->rx_queue.lock, flags); + do { prod = queue->rx.sring->req_prod; cons = queue->rx.req_cons;
Since commit 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") xenvif_rx_ring_slots_available() is no longer called only from the rx queue kernel thread, so it needs to access the rx queue with the associated queue held. Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com> Fixes: 23025393dbeb3b8b3 ("xen/netback: use lateeoi irq binding") Cc: stable@vger.kernel.org Signed-off-by: Juergen Gross <jgross@suse.com> --- drivers/net/xen-netback/rx.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)