[PATCH net] bnxt: do not busy-poll when link is down

When busy polling while a link is down (during a link-flap test), TX
timeouts were observed as well as the following messages in the ring
buffer:

bnxt_en 0008:01:00.2 enP8p1s0f2d2: Resp cmpl intr err msg: 0x51
bnxt_en 0008:01:00.2 enP8p1s0f2d2: hwrm_ring_free tx failed. rc:-1
bnxt_en 0008:01:00.2 enP8p1s0f2d2: Resp cmpl intr err msg: 0x51
bnxt_en 0008:01:00.2 enP8p1s0f2d2: hwrm_ring_free rx failed. rc:-1

These were resolved by checking for link status and returning if link
was not up.

Signed-off-by: Andy Gospodarek <redacted>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Tested-by: Rob Miller <redacted>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index e18635b..013e373 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -1811,6 +1811,9 @@ static int bnxt_busy_poll(struct napi_struct *napi)
 	if (atomic_read(&bp->intr_sem) != 0)
 		return LL_FLUSH_FAILED;
 
+	if (!bp->link_info.link_up)
+		return LL_FLUSH_FAILED;
+
 	if (!bnxt_lock_poll(bnapi))
 		return LL_FLUSH_BUSY;
 

-- 
2.1.0

On Tue, 2016-11-22 at 13:14 -0500, Andy Gospodarek wrote:

Any plans removing this busy polling stuff, now it is done in core
networking stack ?

This would remove bnxt_lock_napi() extra overhead in normal path ( napi
poll )

I could do this but I do not have the hardware to do the tests.

On Tue, Nov 22, 2016 at 10:38 AM, Eric Dumazet [off-list ref] wrote:

On Tue, 2016-11-22 at 13:14 -0500, Andy Gospodarek wrote:

quoted

When busy polling while a link is down (during a link-flap test), TX
timeouts were observed as well as the following messages in the ring
buffer:

bnxt_en 0008:01:00.2 enP8p1s0f2d2: Resp cmpl intr err msg: 0x51
bnxt_en 0008:01:00.2 enP8p1s0f2d2: hwrm_ring_free tx failed. rc:-1
bnxt_en 0008:01:00.2 enP8p1s0f2d2: Resp cmpl intr err msg: 0x51
bnxt_en 0008:01:00.2 enP8p1s0f2d2: hwrm_ring_free rx failed. rc:-1

These were resolved by checking for link status and returning if link
was not up.

Signed-off-by: Andy Gospodarek <redacted>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Tested-by: Rob Miller <redacted>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index e18635b..013e373 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -1811,6 +1811,9 @@ static int bnxt_busy_poll(struct napi_struct *napi)
      if (atomic_read(&bp->intr_sem) != 0)
              return LL_FLUSH_FAILED;

+     if (!bp->link_info.link_up)
+             return LL_FLUSH_FAILED;
+
      if (!bnxt_lock_poll(bnapi))
              return LL_FLUSH_BUSY;

Any plans removing this busy polling stuff, now it is done in core
networking stack ?

This would remove bnxt_lock_napi() extra overhead in normal path ( napi
poll )

I could do this but I do not have the hardware to do the tests.

It's on my list of many TODO things.  Probably in the next few weeks.

On Tue, 2016-11-22 at 10:55 -0800, Michael Chan wrote:

On Tue, Nov 22, 2016 at 10:38 AM, Eric Dumazet [off-list ref] wrote:

quoted

Any plans removing this busy polling stuff, now it is done in core
networking stack ?

This would remove bnxt_lock_napi() extra overhead in normal path ( napi
poll )

I could do this but I do not have the hardware to do the tests.

It's on my list of many TODO things.  Probably in the next few weeks.

Awesome, thanks !

From: Andy Gospodarek <redacted>
Date: Tue, 22 Nov 2016 13:14:08 -0500

When busy polling while a link is down (during a link-flap test), TX
timeouts were observed as well as the following messages in the ring
buffer:

bnxt_en 0008:01:00.2 enP8p1s0f2d2: Resp cmpl intr err msg: 0x51
bnxt_en 0008:01:00.2 enP8p1s0f2d2: hwrm_ring_free tx failed. rc:-1
bnxt_en 0008:01:00.2 enP8p1s0f2d2: Resp cmpl intr err msg: 0x51
bnxt_en 0008:01:00.2 enP8p1s0f2d2: hwrm_ring_free rx failed. rc:-1

These were resolved by checking for link status and returning if link
was not up.

Signed-off-by: Andy Gospodarek <redacted>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Tested-by: Rob Miller <redacted>

Applied.