From: Catherine Sullivan Date: Mon, 17 May 2021 21:08:14 +0000 (-0700) Subject: gve: Upgrade memory barrier in poll routine X-Git-Tag: accepted/tizen/unified/20230118.172025~7163^2~46^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f81781835f0adfae8d701545386030d223efcd6f;p=platform%2Fkernel%2Flinux-rpi.git gve: Upgrade memory barrier in poll routine As currently written, if the driver checks for more work (via gve_tx_poll or gve_rx_poll) before the device posts work and the irq doorbell is not unmasked (via iowrite32be(GVE_IRQ_ACK | GVE_IRQ_EVENT, ...)) before the device attempts to raise an interrupt, an interrupt is lost and this could potentially lead to the traffic being completely halted. For example, if a tx queue has already been stopped, the driver won't get the chance to complete work and egress will be halted. We need a full memory barrier in the poll routine to ensure that the irq doorbell is unmasked before the driver checks for more work. Fixes: f5cedc84a30d ("gve: Add transmit and receive support") Signed-off-by: Catherine Sullivan Signed-off-by: David Awogbemila Acked-by: Willem de Brujin Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c index 21a5d05..bbc423e 100644 --- a/drivers/net/ethernet/google/gve/gve_main.c +++ b/drivers/net/ethernet/google/gve/gve_main.c @@ -180,7 +180,7 @@ static int gve_napi_poll(struct napi_struct *napi, int budget) /* Double check we have no extra work. * Ensure unmask synchronizes with checking for work. */ - dma_rmb(); + mb(); if (block->tx) reschedule |= gve_tx_poll(block, -1); if (block->rx)