ftgmac100: return error in ftgmac100_alloc_rx_buf

Message ID 20170725004901.13406-1-joel@jms.id.au
State New
Headers show

Commit Message

Joel Stanley July 25, 2017, 12:49 a.m.
The error paths set err, but it's not returned.

I wondered if we should fix all of the callers to check the returned
value, but Ben explains why the code is this way:

> Most call sites ignore it on purpose. There's nothing we can do if

> we fail to get a buffer at interrupt time, so we point the buffer to

> the scratch page so the HW doesn't DMA into lalaland and lose the

> packet.

>

> The one call site that tests and can fail is the one used when brining

> the interface up. If we fail to allocate at that point, we fail the

> ifup. But as you noticed, I do have a bug not returning the error.


Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: Joel Stanley <joel@jms.id.au>

---
 drivers/net/ethernet/faraday/ftgmac100.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.13.3

Comments

David Miller July 26, 2017, 4:22 a.m. | #1
From: Joel Stanley <joel@jms.id.au>

Date: Tue, 25 Jul 2017 10:19:01 +0930

> The error paths set err, but it's not returned.

> 

> I wondered if we should fix all of the callers to check the returned

> value, but Ben explains why the code is this way:

> 

>> Most call sites ignore it on purpose. There's nothing we can do if

>> we fail to get a buffer at interrupt time, so we point the buffer to

>> the scratch page so the HW doesn't DMA into lalaland and lose the

>> packet.

>>

>> The one call site that tests and can fail is the one used when brining

>> the interface up. If we fail to allocate at that point, we fail the

>> ifup. But as you noticed, I do have a bug not returning the error.

> 

> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

> Signed-off-by: Joel Stanley <joel@jms.id.au>


Applied, thanks.

Patch

diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c
index fce0aa4f78b7..33b5c8eb9961 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -392,7 +392,7 @@  static int ftgmac100_alloc_rx_buf(struct ftgmac100 *priv, unsigned int entry,
 	struct net_device *netdev = priv->netdev;
 	struct sk_buff *skb;
 	dma_addr_t map;
-	int err;
+	int err = 0;
 
 	skb = netdev_alloc_skb_ip_align(netdev, RX_BUF_SIZE);
 	if (unlikely(!skb)) {
@@ -428,7 +428,7 @@  static int ftgmac100_alloc_rx_buf(struct ftgmac100 *priv, unsigned int entry,
 	else
 		rxdes->rxdes0 = 0;
 
-	return 0;
+	return err;
 }
 
 static unsigned int ftgmac100_next_rx_pointer(struct ftgmac100 *priv,