| Message ID | 1386759436-46737-3-git-send-email-paul.durrant@citrix.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 83b4e5b..fb512a9 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1381,7 +1381,7 @@ static unsigned xenvif_tx_build_gops(struct xenvif *vif, int budget) continue; } - RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do); + work_to_do = RING_HAS_UNCONSUMED_REQUESTS(&vif->tx); if (!work_to_do) break;
This patch changes the RING_FINAL_CHECK_FOR_REQUESTS in xenvif_build_tx_gops to a check for RING_HAS_UNCONSUMED_REQUESTS as the former call has the side effect of advancing the ring event pointer and therefore inviting another interrupt from the frontend before the napi poll has actually finished, thereby defeating the point of napi. The event pointer is updated by RING_FINAL_CHECK_FOR_REQUESTS in xenvif_poll, the napi poll function, if the work done is less than the budget i.e. when actually transitioning back to interrupt mode. Reported-by: Malcolm Crossley <malcolm.crossley@citrix.com> Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Cc: Wei Liu <wei.liu2@citrix.com> Cc: Ian Campbell <ian.campbell@citrix.com> Cc: David Vrabel <david.vrabel@citrix.com> --- drivers/net/xen-netback/netback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)