[PATCH net v4 1/4] tg3: Limit minimum tx queue wakeup threshold

[PATCH net v4 1/4] tg3: Limit minimum tx queue wakeup threshold

[Benjamin Poirier]

tx_pending may be set by the user (via ethtool -G) to a low enough value that
TG3_TX_WAKEUP_THRESH becomes smaller than MAX_SKB_FRAGS + 1. This may cause
the tx queue to be waked when there are in fact not enough descriptors to
handle an skb with max frags. This in turn causes tg3_start_xmit() to return
NETDEV_TX_BUSY and print error messages. Fix the problem by putting a limit to
how low TG3_TX_WAKEUP_THRESH can go.

Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
---

I noticed the problem in a 3.0 kernel when setting `ethtool eth0 -G tx 50` and
running a netperf TCP_STREAM test. The console fills up with
[10597.596155] tg3 0000:06:00.0: eth0: BUG! Tx Ring full when queue awake!
The problem in tg3 remains in current kernels though it does not reproduce as
easily since "5640f76 net: use a per task frag allocator (v3.7-rc1)". I
reproduced on current kernels by using the fail_page_alloc fault injection
mechanism to force the creation of skbs with many order-0 frags. Note that the
following script may also trigger another bug (NETDEV WATCHDOG), which is
fixed in the next patch.

$ cat /tmp/doit.sh

F="/sys/kernel/debug/fail_page_alloc"

echo -1 > "$F/times"
echo 0 > "$F/verbose"
echo 0 > "$F/ignore-gfp-wait"
echo 1 > "$F/task-filter"
echo 100 > "$F/probability"

netperf -H 192.168.9.30 -l100 -t omni -- -d send &

n=$!

sleep 0.3
echo 1 > "/proc/$n/make-it-fail"
sleep 10

kill "$n"
---
 drivers/net/ethernet/broadcom/tg3.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 3ac5d23..b11c0fd 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -202,7 +202,8 @@ static inline void _tg3_flag_clear(enum TG3_FLAGS flag, unsigned long *bits)
 #endif
 
 /* minimum number of free TX descriptors required to wake up TX process */
-#define TG3_TX_WAKEUP_THRESH(tnapi)		((tnapi)->tx_pending / 4)
+#define TG3_TX_WAKEUP_THRESH(tnapi)	max_t(u32, (tnapi)->tx_pending / 4, \
+					      MAX_SKB_FRAGS + 1)
 #define TG3_TX_BD_DMA_MAX_2K		2048
 #define TG3_TX_BD_DMA_MAX_4K		4096
 
-- 
1.8.4.5

[PATCH net v4 2/4] tg3: Fix tx_pending check for MAX_SKB_FRAGS

[Benjamin Poirier]

The rest of the driver assumes at least one free descriptor in the tx ring.
Therefore, since an skb with max frags takes up (MAX_SKB_FRAGS + 1)
descriptors, tx_pending must be > (MAX_SKB_FRAGS + 1).

Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
---

Changes v1->v2
Moved ahead in the series from 3/3 to 2/3, no functionnal change

I reproduced this bug using the same approach explained in patch 1.
The bug reproduces with tx_pending = 18
---
 drivers/net/ethernet/broadcom/tg3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index b11c0fd..0cecd6d 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -12319,7 +12319,7 @@ static int tg3_set_ringparam(struct net_device *dev, struct ethtool_ringparam *e
 	if ((ering->rx_pending > tp->rx_std_ring_mask) ||
 	    (ering->rx_jumbo_pending > tp->rx_jmb_ring_mask) ||
 	    (ering->tx_pending > TG3_TX_RING_SIZE - 1) ||
-	    (ering->tx_pending <= MAX_SKB_FRAGS) ||
+	    (ering->tx_pending <= MAX_SKB_FRAGS + 1) ||
 	    (tg3_flag(tp, TSO_BUG) &&
 	     (ering->tx_pending <= (MAX_SKB_FRAGS * 3))))
 		return -EINVAL;
-- 
1.8.4.5

[PATCH net v4 3/4] tg3: Move tx queue stop logic to its own function

[Benjamin Poirier]

It is duplicated. Also, the first instance in tg3_start_xmit() is racy.
Consider:

tg3_start_xmit()
	if budget <= ...
				tg3_tx()
					(free up the entire ring)
					tx_cons =
					smp_mb
					if queue_stopped and tx_avail, NO
		if !queue_stopped
			stop queue
		return NETDEV_TX_BUSY

... tx queue stopped forever

Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
---
Changes v2->v3
* new patch to avoid repeatedly open coding this block in the next patch.

Changes v3->v4
* added a comment to clarify the return value, as suggested
* replaced the BUG_ON with netdev_err(). No need to be so dramatic, this
  situation will trigger a netdev watchdog anyways.
---
 drivers/net/ethernet/broadcom/tg3.c | 75 ++++++++++++++++++++-----------------
 1 file changed, 40 insertions(+), 35 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 0cecd6d..f706a1e 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -7831,6 +7831,35 @@ static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
 
 static netdev_tx_t tg3_start_xmit(struct sk_buff *, struct net_device *);
 
+/* Returns true if the queue has been stopped. Note that it may have been
+ * restarted since.
+ */
+static inline bool tg3_maybe_stop_txq(struct tg3_napi *tnapi,
+				      struct netdev_queue *txq,
+				      u32 stop_thresh, u32 wakeup_thresh)
+{
+	bool stopped = false;
+
+	if (unlikely(tg3_tx_avail(tnapi) <= stop_thresh)) {
+		if (!netif_tx_queue_stopped(txq)) {
+			stopped = true;
+			netif_tx_stop_queue(txq);
+			if (wakeup_thresh >= tnapi->tx_pending)
+				netdev_err(tnapi->tp->dev,
+					   "BUG! wakeup_thresh too large (%u >= %u)\n",
+					   wakeup_thresh, tnapi->tx_pending);
+		}
+		/* netif_tx_stop_queue() must be done before checking tx index
+		 * in tg3_tx_avail(), because in tg3_tx(), we update tx index
+		 * before checking for netif_tx_queue_stopped().
+		 */
+		smp_mb();
+		if (tg3_tx_avail(tnapi) > wakeup_thresh)
+			netif_tx_wake_queue(txq);
+	}
+	return stopped;
+}
+
 /* Use GSO to workaround all TSO packets that meet HW bug conditions
  * indicated in tg3_tx_frag_set()
  */
@@ -7841,20 +7870,9 @@ static int tg3_tso_bug(struct tg3 *tp, struct tg3_napi *tnapi,
 	u32 frag_cnt_est = skb_shinfo(skb)->gso_segs * 3;
 
 	/* Estimate the number of fragments in the worst case */
-	if (unlikely(tg3_tx_avail(tnapi) <= frag_cnt_est)) {
-		netif_tx_stop_queue(txq);
-
-		/* netif_tx_stop_queue() must be done before checking
-		 * checking tx index in tg3_tx_avail() below, because in
-		 * tg3_tx(), we update tx index before checking for
-		 * netif_tx_queue_stopped().
-		 */
-		smp_mb();
-		if (tg3_tx_avail(tnapi) <= frag_cnt_est)
-			return NETDEV_TX_BUSY;
-
-		netif_tx_wake_queue(txq);
-	}
+	tg3_maybe_stop_txq(tnapi, txq, frag_cnt_est, frag_cnt_est);
+	if (netif_tx_queue_stopped(txq))
+		return NETDEV_TX_BUSY;
 
 	segs = skb_gso_segment(skb, tp->dev->features &
 				    ~(NETIF_F_TSO | NETIF_F_TSO6));
@@ -7902,16 +7920,13 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * interrupt.  Furthermore, IRQ processing runs lockless so we have
 	 * no IRQ context deadlocks to worry about either.  Rejoice!
 	 */
-	if (unlikely(budget <= (skb_shinfo(skb)->nr_frags + 1))) {
-		if (!netif_tx_queue_stopped(txq)) {
-			netif_tx_stop_queue(txq);
-
-			/* This is a hard error, log it. */
-			netdev_err(dev,
-				   "BUG! Tx Ring full when queue awake!\n");
-		}
-		return NETDEV_TX_BUSY;
+	if (tg3_maybe_stop_txq(tnapi, txq, skb_shinfo(skb)->nr_frags + 1,
+			       TG3_TX_WAKEUP_THRESH(tnapi))) {
+		/* This is a hard error, log it. */
+		netdev_err(dev, "BUG! Tx Ring full when queue awake!\n");
 	}
+	if (netif_tx_queue_stopped(txq))
+		return NETDEV_TX_BUSY;
 
 	entry = tnapi->tx_prod;
 	base_flags = 0;
@@ -8087,18 +8102,8 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	tw32_tx_mbox(tnapi->prodmbox, entry);
 
 	tnapi->tx_prod = entry;
-	if (unlikely(tg3_tx_avail(tnapi) <= (MAX_SKB_FRAGS + 1))) {
-		netif_tx_stop_queue(txq);
-
-		/* netif_tx_stop_queue() must be done before checking
-		 * checking tx index in tg3_tx_avail() below, because in
-		 * tg3_tx(), we update tx index before checking for
-		 * netif_tx_queue_stopped().
-		 */
-		smp_mb();
-		if (tg3_tx_avail(tnapi) > TG3_TX_WAKEUP_THRESH(tnapi))
-			netif_tx_wake_queue(txq);
-	}
+	tg3_maybe_stop_txq(tnapi, txq, MAX_SKB_FRAGS + 1,
+			   TG3_TX_WAKEUP_THRESH(tnapi));
 
 	mmiowb();
 	return NETDEV_TX_OK;
-- 
1.8.4.5

[PATCH net v4 4/4] tg3: Fix tx_pending checks for tg3_tso_bug

[Benjamin Poirier]

In tg3_set_ringparam(), the tx_pending test to cover the cases where
tg3_tso_bug() is entered has two problems
1) the check is only done for certain hardware whereas the workaround
is now used more broadly. IOW, the check may not be performed when it
is needed.
2) the check is too optimistic.

For example, with a 5761 (SHORT_DMA_BUG), tg3_set_ringparam() skips over the
"tx_pending <= (MAX_SKB_FRAGS * 3)" check because TSO_BUG is false. Even if it
did do the check, with a full sized skb, frag_cnt_est = 135 but the check is
for <= MAX_SKB_FRAGS * 3 (= 17 * 3 = 51). So the check is insufficient. This
leads to the following situation: by setting, ex. tx_pending = 100, there can
be an skb that triggers tg3_tso_bug() and that is large enough to cause
tg3_tso_bug() to stop the queue even when it is empty. We then end up with a
netdev watchdog transmit timeout.

Given that 1) some of the conditions tested for in tg3_tx_frag_set() apply
regardless of the chipset flags and that 2) it is difficult to estimate ahead
of time the max possible number of frames that a large skb may be split into
by gso, we instead take the approach of adjusting dev->gso_max_segs according
to the requested tx_pending size.

This puts us in the exceptional situation that a single skb that triggers
tg3_tso_bug() may require the entire tx ring. Usually the tx queue is woken up
when at least a quarter of it is available (TG3_TX_WAKEUP_THRESH) but that
would be insufficient now. To avoid useless wakeups, the tx queue wake up
threshold is made dynamic. Likewise, usually the tx queue is stopped as soon
as an skb with max frags may overrun it. Since the skbs submitted from
tg3_tso_bug() use a controlled number of descriptors, the tx queue stop
threshold may be lowered.

Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
---

Changes v1->v2
* in tg3_set_ringparam(), reduce gso_max_segs further to budget 3 descriptors
  per gso seg instead of only 1 as in v1
* in tg3_tso_bug(), check that this estimation (3 desc/seg) holds, otherwise
  linearize some skbs as needed
* in tg3_start_xmit(), make the queue stop threshold a parameter, for the
  reason explained in the commit description

Changes v2->v3
* use tg3_maybe_stop_txq() instead of repeatedly open coding it
* add the requested tp->tx_dropped++ stat increase in tg3_tso_bug() if
  skb_linearize() fails and we must abort
* in the same code block, add an additional check to stop the queue with the
  default threshold. Otherwise, the netdev_err message at the start of
  __tg3_start_xmit() could be triggered when the next frame is transmitted.
  That is because the previous calls to __tg3_start_xmit() in tg3_tso_bug()
  may have been using a stop_thresh=segs_remaining that is < MAX_SKB_FRAGS +
  1.

Changes v3->v4
* in tg3_set_ringparam(), make sure that wakeup_thresh does not end up being
  >= tx_pending. Identified by Prashant.

I reproduced this bug using the same approach explained in patch 1.
The bug reproduces with tx_pending <= 135
---
 drivers/net/ethernet/broadcom/tg3.c | 70 +++++++++++++++++++++++++++++--------
 drivers/net/ethernet/broadcom/tg3.h |  1 +
 2 files changed, 57 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index f706a1e..05cb940 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -204,6 +204,10 @@ static inline void _tg3_flag_clear(enum TG3_FLAGS flag, unsigned long *bits)
 /* minimum number of free TX descriptors required to wake up TX process */
 #define TG3_TX_WAKEUP_THRESH(tnapi)	max_t(u32, (tnapi)->tx_pending / 4, \
 					      MAX_SKB_FRAGS + 1)
+/* estimate a certain number of descriptors per gso segment */
+#define TG3_TX_DESC_PER_SEG(seg_nb)	((seg_nb) * 3)
+#define TG3_TX_SEG_PER_DESC(desc_nb)	((desc_nb) / 3)
+
 #define TG3_TX_BD_DMA_MAX_2K		2048
 #define TG3_TX_BD_DMA_MAX_4K		4096
 
@@ -6609,10 +6613,10 @@ static void tg3_tx(struct tg3_napi *tnapi)
 	smp_mb();
 
 	if (unlikely(netif_tx_queue_stopped(txq) &&
-		     (tg3_tx_avail(tnapi) > TG3_TX_WAKEUP_THRESH(tnapi)))) {
+		     (tg3_tx_avail(tnapi) > tnapi->wakeup_thresh))) {
 		__netif_tx_lock(txq, smp_processor_id());
 		if (netif_tx_queue_stopped(txq) &&
-		    (tg3_tx_avail(tnapi) > TG3_TX_WAKEUP_THRESH(tnapi)))
+		    (tg3_tx_avail(tnapi) > tnapi->wakeup_thresh))
 			netif_tx_wake_queue(txq);
 		__netif_tx_unlock(txq);
 	}
@@ -7830,6 +7834,8 @@ static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
 }
 
 static netdev_tx_t tg3_start_xmit(struct sk_buff *, struct net_device *);
+static netdev_tx_t __tg3_start_xmit(struct sk_buff *, struct net_device *,
+				    u32);
 
 /* Returns true if the queue has been stopped. Note that it may have been
  * restarted since.
@@ -7844,6 +7850,7 @@ static inline bool tg3_maybe_stop_txq(struct tg3_napi *tnapi,
 		if (!netif_tx_queue_stopped(txq)) {
 			stopped = true;
 			netif_tx_stop_queue(txq);
+			tnapi->wakeup_thresh = wakeup_thresh;
 			if (wakeup_thresh >= tnapi->tx_pending)
 				netdev_err(tnapi->tp->dev,
 					   "BUG! wakeup_thresh too large (%u >= %u)\n",
@@ -7851,10 +7858,11 @@ static inline bool tg3_maybe_stop_txq(struct tg3_napi *tnapi,
 		}
 		/* netif_tx_stop_queue() must be done before checking tx index
 		 * in tg3_tx_avail(), because in tg3_tx(), we update tx index
-		 * before checking for netif_tx_queue_stopped().
+		 * before checking for netif_tx_queue_stopped(). The memory
+		 * barrier also synchronizes wakeup_thresh changes.
 		 */
 		smp_mb();
-		if (tg3_tx_avail(tnapi) > wakeup_thresh)
+		if (tg3_tx_avail(tnapi) > tnapi->wakeup_thresh)
 			netif_tx_wake_queue(txq);
 	}
 	return stopped;
@@ -7867,10 +7875,10 @@ static int tg3_tso_bug(struct tg3 *tp, struct tg3_napi *tnapi,
 		       struct netdev_queue *txq, struct sk_buff *skb)
 {
 	struct sk_buff *segs, *nskb;
-	u32 frag_cnt_est = skb_shinfo(skb)->gso_segs * 3;
+	unsigned int segs_remaining = skb_shinfo(skb)->gso_segs;
+	u32 desc_cnt_est = TG3_TX_DESC_PER_SEG(segs_remaining);
 
-	/* Estimate the number of fragments in the worst case */
-	tg3_maybe_stop_txq(tnapi, txq, frag_cnt_est, frag_cnt_est);
+	tg3_maybe_stop_txq(tnapi, txq, desc_cnt_est, desc_cnt_est);
 	if (netif_tx_queue_stopped(txq))
 		return NETDEV_TX_BUSY;
 
@@ -7880,10 +7888,32 @@ static int tg3_tso_bug(struct tg3 *tp, struct tg3_napi *tnapi,
 		goto tg3_tso_bug_end;
 
 	do {
+		unsigned int desc_cnt = skb_shinfo(segs)->nr_frags + 1;
+
 		nskb = segs;
 		segs = segs->next;
 		nskb->next = NULL;
-		tg3_start_xmit(nskb, tp->dev);
+
+		if (tg3_tx_avail(tnapi) <= segs_remaining - 1 + desc_cnt &&
+		    skb_linearize(nskb)) {
+			tp->tx_dropped++;
+			nskb->next = segs;
+			segs = nskb;
+			do {
+				nskb = segs->next;
+
+				dev_kfree_skb_any(segs);
+				segs = nskb;
+			} while (segs);
+			tg3_maybe_stop_txq(tnapi, txq, MAX_SKB_FRAGS + 1,
+					   TG3_TX_WAKEUP_THRESH(tnapi));
+			goto tg3_tso_bug_end;
+		}
+		segs_remaining--;
+		if (segs_remaining)
+			__tg3_start_xmit(nskb, tp->dev, segs_remaining);
+		else
+			tg3_start_xmit(nskb, tp->dev);
 	} while (segs);
 
 tg3_tso_bug_end:
@@ -7895,6 +7925,12 @@ tg3_tso_bug_end:
 /* hard_start_xmit for all devices */
 static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
+	return __tg3_start_xmit(skb, dev, MAX_SKB_FRAGS + 1);
+}
+
+static netdev_tx_t __tg3_start_xmit(struct sk_buff *skb,
+				    struct net_device *dev, u32 stop_thresh)
+{
 	struct tg3 *tp = netdev_priv(dev);
 	u32 len, entry, base_flags, mss, vlan = 0;
 	u32 budget;
@@ -8102,7 +8138,7 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	tw32_tx_mbox(tnapi->prodmbox, entry);
 
 	tnapi->tx_prod = entry;
-	tg3_maybe_stop_txq(tnapi, txq, MAX_SKB_FRAGS + 1,
+	tg3_maybe_stop_txq(tnapi, txq, stop_thresh,
 			   TG3_TX_WAKEUP_THRESH(tnapi));
 
 	mmiowb();
@@ -12324,9 +12360,7 @@ static int tg3_set_ringparam(struct net_device *dev, struct ethtool_ringparam *e
 	if ((ering->rx_pending > tp->rx_std_ring_mask) ||
 	    (ering->rx_jumbo_pending > tp->rx_jmb_ring_mask) ||
 	    (ering->tx_pending > TG3_TX_RING_SIZE - 1) ||
-	    (ering->tx_pending <= MAX_SKB_FRAGS + 1) ||
-	    (tg3_flag(tp, TSO_BUG) &&
-	     (ering->tx_pending <= (MAX_SKB_FRAGS * 3))))
+	    (ering->tx_pending <= MAX_SKB_FRAGS + 1))
 		return -EINVAL;
 
 	if (netif_running(dev)) {
@@ -12346,8 +12380,15 @@ static int tg3_set_ringparam(struct net_device *dev, struct ethtool_ringparam *e
 	if (tg3_flag(tp, JUMBO_RING_ENABLE))
 		tp->rx_jumbo_pending = ering->rx_jumbo_pending;
 
-	for (i = 0; i < tp->irq_max; i++)
-		tp->napi[i].tx_pending = ering->tx_pending;
+	dev->gso_max_segs = TG3_TX_SEG_PER_DESC(ering->tx_pending - 1);
+	for (i = 0; i < tp->irq_max; i++) {
+		struct tg3_napi *tnapi = &tp->napi[i];
+
+		tnapi->tx_pending = ering->tx_pending;
+		if (netif_tx_queue_stopped(netdev_get_tx_queue(dev, i)) &&
+		    tnapi->wakeup_thresh >= ering->tx_pending)
+			tnapi->wakeup_thresh = MAX_SKB_FRAGS + 1;
+	}
 
 	if (netif_running(dev)) {
 		tg3_halt(tp, RESET_KIND_SHUTDOWN, 1);
@@ -17822,6 +17863,7 @@ static int tg3_init_one(struct pci_dev *pdev,
 		else
 			sndmbx += 0xc;
 	}
+	dev->gso_max_segs = TG3_TX_SEG_PER_DESC(TG3_DEF_TX_RING_PENDING - 1);
 
 	tg3_init_coal(tp);
 
diff --git a/drivers/net/ethernet/broadcom/tg3.h b/drivers/net/ethernet/broadcom/tg3.h
index 461acca..6a7e13d 100644
--- a/drivers/net/ethernet/broadcom/tg3.h
+++ b/drivers/net/ethernet/broadcom/tg3.h
@@ -3006,6 +3006,7 @@ struct tg3_napi {
 	u32				tx_pending;
 	u32				last_tx_cons;
 	u32				prodmbox;
+	u32				wakeup_thresh;
 	struct tg3_tx_buffer_desc	*tx_ring;
 	struct tg3_tx_ring_info		*tx_buffers;
 
-- 
1.8.4.5

Re: [PATCH net v4 4/4] tg3: Fix tx_pending checks for tg3_tso_bug

[Prashant Sreedharan]

>  	if (netif_running(dev)) {
> @@ -12346,8 +12380,15 @@ static int tg3_set_ringparam(struct net_device *dev, struct ethtool_ringparam *e
>  	if (tg3_flag(tp, JUMBO_RING_ENABLE))
>  		tp->rx_jumbo_pending = ering->rx_jumbo_pending;
>  
> -	for (i = 0; i < tp->irq_max; i++)
> -		tp->napi[i].tx_pending = ering->tx_pending;
> +	dev->gso_max_segs = TG3_TX_SEG_PER_DESC(ering->tx_pending - 1);
> +	for (i = 0; i < tp->irq_max; i++) {
> +		struct tg3_napi *tnapi = &tp->napi[i];
> +
> +		tnapi->tx_pending = ering->tx_pending;
> +		if (netif_tx_queue_stopped(netdev_get_tx_queue(dev, i)) &&
> +		    tnapi->wakeup_thresh >= ering->tx_pending)
> +			tnapi->wakeup_thresh = MAX_SKB_FRAGS + 1;

To maintain consistency wakeup_thresh can be set to TG3_TX_WAKEUP_THRESH
similar to other parts of the code, except the special handling of
tg3_tso_bug() estimate.
 
> +	}
>  
>  	if (netif_running(dev)) {
>  		tg3_halt(tp, RESET_KIND_SHUTDOWN, 1);
> @@ -17822,6 +17863,7 @@ static int tg3_init_one(struct pci_dev *pdev,
>  		else
>  			sndmbx += 0xc;
>  	}

Re: [PATCH net v4 4/4] tg3: Fix tx_pending checks for tg3_tso_bug

[Prashant Sreedharan]

>  
> -	for (i = 0; i < tp->irq_max; i++)
> -		tp->napi[i].tx_pending = ering->tx_pending;
> +	dev->gso_max_segs = TG3_TX_SEG_PER_DESC(ering->tx_pending - 1);
> +	for (i = 0; i < tp->irq_max; i++) {
> +		struct tg3_napi *tnapi = &tp->napi[i];
> +
> +		tnapi->tx_pending = ering->tx_pending;
> +		if (netif_tx_queue_stopped(netdev_get_tx_queue(dev, i)) &&

Need to limit the number of TX queues to tp->txq_cnt instead of
tp->irq_max as txq_cnt can be less than irq_max.

netif_set_real_num_tx_queues(tp->dev, tp->txq_cnt);

> +		    tnapi->wakeup_thresh >= ering->tx_pending)
> +			tnapi->wakeup_thresh = MAX_SKB_FRAGS + 1;
> +	}
>  

Re: [PATCH net v4 4/4] tg3: Fix tx_pending checks for tg3_tso_bug

[Benjamin Poirier]

On 2014/08/28 20:24, Prashant Sreedharan wrote:
> >  
> > -	for (i = 0; i < tp->irq_max; i++)
> > -		tp->napi[i].tx_pending = ering->tx_pending;
> > +	dev->gso_max_segs = TG3_TX_SEG_PER_DESC(ering->tx_pending - 1);
> > +	for (i = 0; i < tp->irq_max; i++) {
> > +		struct tg3_napi *tnapi = &tp->napi[i];
> > +
> > +		tnapi->tx_pending = ering->tx_pending;
> > +		if (netif_tx_queue_stopped(netdev_get_tx_queue(dev, i)) &&
> 
> Need to limit the number of TX queues to tp->txq_cnt instead of
> tp->irq_max as txq_cnt can be less than irq_max.
> 
> netif_set_real_num_tx_queues(tp->dev, tp->txq_cnt);

Thanks for your careful review, I'll resubmit shortly.

> 
> > +		    tnapi->wakeup_thresh >= ering->tx_pending)
> > +			tnapi->wakeup_thresh = MAX_SKB_FRAGS + 1;
> > +	}
> >  
> 
> 
>