[PATCH 3.10 05/50] alx: fix alx_poll()

Greg Kroah-Hartman
2015-01-25T19:34:01Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 7a05dc64e2e4c611d89007b125b20c0d2a4d31a5 ]

Commit d75b1ade567f ("net: less interrupt masking in NAPI") uncovered
wrong alx_poll() behavior.

A NAPI poll() handler is supposed to return exactly the budget when/if
napi_complete() has not been called.

It is also supposed to return number of frames that were received, so
that netdev_budget can have a meaning.

Also, in case of TX pressure, we still have to dequeue received
packets : alx_clean_rx_irq() has to be called even if
alx_clean_tx_irq(alx) returns false, otherwise device is half duplex.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: d75b1ade567f ("net: less interrupt masking in NAPI")
Reported-by: Oded Gabbay <oded.gabbay@amd.com>
Bisected-by: Oded Gabbay <oded.gabbay@amd.com>
Tested-by: Oded Gabbay <oded.gabbay@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/atheros/alx/main.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

--- a/drivers/net/ethernet/atheros/alx/main.c
+++ b/drivers/net/ethernet/atheros/alx/main.c
@@ -184,15 +184,16 @@ static void alx_schedule_reset(struct al
schedule_work(&alx->reset_wk);
}

-static bool alx_clean_rx_irq(struct alx_priv *alx, int budget)
+static int alx_clean_rx_irq(struct alx_priv *alx, int budget)
{
struct alx_rx_queue *rxq = &alx->rxq;
struct alx_rrd *rrd;
struct alx_buffer *rxb;
struct sk_buff *skb;
u16 length, rfd_cleaned = 0;
+ int work = 0;

- while (budget > 0) {
+ while (work < budget) {
rrd = &rxq->rrd[rxq->rrd_read_idx];
if (!(rrd->word3 & cpu_to_le32(1 << RRD_UPDATED_SHIFT)))
break;
@@ -203,7 +204,7 @@ static bool alx_clean_rx_irq(struct alx_
ALX_GET_FIELD(le32_to_cpu(rrd->word0),
RRD_NOR) != 1) {
alx_schedule_reset(alx);
- return 0;
+ return work;
}

rxb = &rxq->bufs[rxq->read_idx];
@@ -243,7 +244,7 @@ static bool alx_clean_rx_irq(struct alx_
}

napi_gro_receive(&alx->napi, skb);
- budget--;
+ work++;

next_pkt:
if (++rxq->read_idx == alx->rx_ringsz)
@@ -258,21 +259,22 @@ next_pkt:
if (rfd_cleaned)
alx_refill_rx_ring(alx, GFP_ATOMIC);

- return budget > 0;
+ return work;
}

static int alx_poll(struct napi_struct *napi, int budget)
{
struct alx_priv *alx = container_of(napi, struct alx_priv, napi);
struct alx_hw *hw = &alx->hw;
- bool complete = true;
unsigned long flags;
+ bool tx_complete;
+ int work;

- complete = alx_clean_tx_irq(alx) &&
- alx_clean_rx_irq(alx, budget);
+ tx_complete = alx_clean_tx_irq(alx);
+ work = alx_clean_rx_irq(alx, budget);

- if (!complete)
- return 1;
+ if (!tx_complete || work == budget)
+ return budget;

napi_complete(&alx->napi);

@@ -284,7 +286,7 @@ static int alx_poll(struct napi_struct *

alx_post_write(hw);

- return 0;
+ return work;
}

static irqreturn_t alx_intr_handle(struct alx_priv *alx, u32 intr)