From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: netdev@vger•kernel.org
Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Subject: [PATCH v2 8/9] ftgmac100: Fix potential ordering issue in NAPI poll
Date: Thu, 13 Apr 2017 14:39:15 +1000 [thread overview]
Message-ID: <20170413043916.7793-9-benh@kernel.crashing.org> (raw)
In-Reply-To: <20170413043916.7793-1-benh@kernel.crashing.org>
We need to ensure the loads from the descriptor are done after the
MMIO store clearing the interrupts has completed, otherwise we
might still miss work.
A read back from the MMIO register will "push" the posted store and
ioread32 has a barrier on weakly aordered architectures that will
order subsequent accesses.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel•crashing.org>
---
drivers/net/ethernet/faraday/ftgmac100.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
index 71763e4..9b7a24e 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -1347,6 +1347,13 @@ static int ftgmac100_poll(struct napi_struct *napi, int budget)
*/
iowrite32(FTGMAC100_INT_RXTX,
priv->base + FTGMAC100_OFFSET_ISR);
+
+ /* Push the above (and provides a barrier vs. subsequent
+ * reads of the descriptor).
+ */
+ ioread32(priv->base + FTGMAC100_OFFSET_ISR);
+
+ /* Check RX and TX descriptors for more work to do */
if (ftgmac100_check_rx(priv) ||
ftgmac100_tx_buf_cleanable(priv))
return budget;
--
2.9.3
next prev parent reply other threads:[~2017-04-13 4:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 4:39 [PATCH v2 0/9] ftgmac100: Rework batch 5 - Features Benjamin Herrenschmidt
2017-04-13 4:39 ` [PATCH v2 1/9] ftgmac100: Add ethtool n-way reset call Benjamin Herrenschmidt
2017-04-13 4:39 ` [PATCH v2 2/9] ftgmac100: Add pause frames configuration and support Benjamin Herrenschmidt
2017-04-13 4:39 ` [PATCH v2 3/9] ftgmac100: Add ndo_set_rx_mode() and support for multicast & promisc Benjamin Herrenschmidt
2017-04-13 4:39 ` [PATCH v2 4/9] ftgmac100: Add vlan HW offload Benjamin Herrenschmidt
2017-04-13 4:39 ` [PATCH v2 5/9] ftgmac100: Add netpoll support Benjamin Herrenschmidt
2017-04-13 4:39 ` [PATCH v2 6/9] ftgmac100: Allow configuration of phy interface via device-tree Benjamin Herrenschmidt
2017-04-13 4:39 ` [PATCH v2 7/9] ftgmac100: Display the discovered PHY device info Benjamin Herrenschmidt
2017-04-13 4:39 ` Benjamin Herrenschmidt [this message]
2017-04-13 4:39 ` [PATCH v2 9/9] ftgmac100: Document device-tree binding Benjamin Herrenschmidt
2017-04-17 15:11 ` [PATCH v2 0/9] ftgmac100: Rework batch 5 - Features David Miller
2017-04-17 20:44 ` Benjamin Herrenschmidt
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