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Date: Mon, 30 Jul 2012 18:17:17 +0100
From: Ben Hutchings <bhutchings@...arflare.com>
To: David Miller <davem@...emloft.net>
CC: <netdev@...r.kernel.org>, <linux-net-drivers@...arflare.com>
Subject: [PATCH net 2/2] sfc: Correct the minimum TX queue size
Currently an skb requiring TSO may not fit within a minimum-size TX
queue. The TX queue selected for the skb may stall and trigger the TX
watchdog repeatedly (since the problem skb will be retried after the
TX reset). This issue is designated as CVE-2012-3412.
The preceding change 'tcp: Limit number of segments generated by GSO
per skb' fixed this for the default queue size. Increase the minimum
to allow for 2 worst-case skbs, such that there will definitely be
space to add an skb after we wake a queue.
To avoid invalidating existing configurations, change
efx_ethtool_set_ringparam() to fix up values that are too small rather
than returning -EINVAL.
Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
---
drivers/net/ethernet/sfc/efx.c | 5 +++++
drivers/net/ethernet/sfc/efx.h | 11 +++++++----
drivers/net/ethernet/sfc/ethtool.c | 16 +++++++++++-----
drivers/net/ethernet/sfc/tx.c | 20 ++++++++++++++++++++
4 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 70554a1..a5b5a75 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1503,6 +1503,11 @@ static int efx_probe_all(struct efx_nic *efx)
goto fail2;
}
+ BUILD_BUG_ON(EFX_DEFAULT_DMAQ_SIZE < EFX_RXQ_MIN_ENT);
+ if (WARN_ON(EFX_DEFAULT_DMAQ_SIZE < EFX_TXQ_MIN_ENT(efx))) {
+ rc = -EINVAL;
+ goto fail3;
+ }
efx->rxq_entries = efx->txq_entries = EFX_DEFAULT_DMAQ_SIZE;
rc = efx_probe_filters(efx);
diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
index be8f915..d95309c 100644
--- a/drivers/net/ethernet/sfc/efx.h
+++ b/drivers/net/ethernet/sfc/efx.h
@@ -30,6 +30,7 @@ extern netdev_tx_t
efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb);
extern void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index);
extern int efx_setup_tc(struct net_device *net_dev, u8 num_tc);
+extern unsigned int efx_tx_max_skb_descs(struct efx_nic *efx);
/* RX */
extern int efx_probe_rx_queue(struct efx_rx_queue *rx_queue);
@@ -52,10 +53,12 @@ extern void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue);
#define EFX_MAX_EVQ_SIZE 16384UL
#define EFX_MIN_EVQ_SIZE 512UL
-/* The smallest [rt]xq_entries that the driver supports. Callers of
- * efx_wake_queue() assume that they can subsequently send at least one
- * skb. Falcon/A1 may require up to three descriptors per skb_frag. */
-#define EFX_MIN_RING_SIZE (roundup_pow_of_two(2 * 3 * MAX_SKB_FRAGS))
+/* The smallest [rt]xq_entries that the driver supports. RX minimum
+ * is a bit arbitrary. For TX, we must have space for at least 2
+ * TSO skbs.
+ */
+#define EFX_RXQ_MIN_ENT 128U
+#define EFX_TXQ_MIN_ENT(efx) (2 * efx_tx_max_skb_descs(efx))
/* Filters */
extern int efx_probe_filters(struct efx_nic *efx);
diff --git a/drivers/net/ethernet/sfc/ethtool.c b/drivers/net/ethernet/sfc/ethtool.c
index 10536f9..8cba2df 100644
--- a/drivers/net/ethernet/sfc/ethtool.c
+++ b/drivers/net/ethernet/sfc/ethtool.c
@@ -680,21 +680,27 @@ static int efx_ethtool_set_ringparam(struct net_device *net_dev,
struct ethtool_ringparam *ring)
{
struct efx_nic *efx = netdev_priv(net_dev);
+ u32 txq_entries;
if (ring->rx_mini_pending || ring->rx_jumbo_pending ||
ring->rx_pending > EFX_MAX_DMAQ_SIZE ||
ring->tx_pending > EFX_MAX_DMAQ_SIZE)
return -EINVAL;
- if (ring->rx_pending < EFX_MIN_RING_SIZE ||
- ring->tx_pending < EFX_MIN_RING_SIZE) {
+ if (ring->rx_pending < EFX_RXQ_MIN_ENT) {
netif_err(efx, drv, efx->net_dev,
- "TX and RX queues cannot be smaller than %ld\n",
- EFX_MIN_RING_SIZE);
+ "RX queues cannot be smaller than %u\n",
+ EFX_RXQ_MIN_ENT);
return -EINVAL;
}
- return efx_realloc_channels(efx, ring->rx_pending, ring->tx_pending);
+ txq_entries = max(ring->tx_pending, EFX_TXQ_MIN_ENT(efx));
+ if (txq_entries != ring->tx_pending)
+ netif_warn(efx, drv, efx->net_dev,
+ "increasing TX queue size to minimum of %u\n",
+ txq_entries);
+
+ return efx_realloc_channels(efx, ring->rx_pending, txq_entries);
}
static int efx_ethtool_set_pauseparam(struct net_device *net_dev,
diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 9b225a7..814bd17 100644
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -15,6 +15,7 @@
#include <linux/ipv6.h>
#include <linux/slab.h>
#include <net/ipv6.h>
+#include <net/tcp.h>
#include <linux/if_ether.h>
#include <linux/highmem.h>
#include "net_driver.h"
@@ -119,6 +120,25 @@ efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr)
return len;
}
+unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
+{
+ /* Header and payload descriptor for each output segment, plus
+ * one for every input fragment boundary within a segment
+ */
+ unsigned int max_descs = TCP_MAX_GSO_SEGS * 2 + MAX_SKB_FRAGS;
+
+ /* Possibly one more per segment for the alignment workaround */
+ if (EFX_WORKAROUND_5391(efx))
+ max_descs += TCP_MAX_GSO_SEGS;
+
+ /* Possibly more for PCIe page boundaries within input fragments */
+ if (PAGE_SIZE > EFX_PAGE_SIZE)
+ max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
+ DIV_ROUND_UP(GSO_MAX_SIZE, EFX_PAGE_SIZE));
+
+ return max_descs;
+}
+
/*
* Add a socket buffer to a TX queue
*
--
1.7.7.6
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
--
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