net: fec: fix fec_enet_get_free_txdesc_num

tkisky · davem330 · commit 93c595f7b8c5 · 2016-02-11T06:14:51.000-05:00
When first initialized, cur_tx points to the 1st
entry in the queue, and dirty_tx points to the last.
At this point, fec_enet_get_free_txdesc_num will
return tx_ring_size -2. If tx_ring_size -2 entries
are now queued, then fec_enet_get_free_txdesc_num
should return 0, but it returns tx_ring_size instead.

Signed-off-by: Troy Kisky &lt;troy.kisky@boundarydevices.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
@@ -296,7 +296,7 @@ static int fec_enet_get_free_txdesc_num(struct fec_enet_private *fep,
 	entries = ((const char *)txq->dirty_tx -
 			(const char *)txq->cur_tx) / fep->bufdesc_size - 1;
 
-	return entries > 0 ? entries : entries + txq->tx_ring_size;
+	return entries >= 0 ? entries : entries + txq->tx_ring_size;
 }
 
 static void swap_buffer(void *bufaddr, int len)

Original file line number	Diff line number	Diff line change
`@@ -296,7 +296,7 @@ static int fec_enet_get_free_txdesc_num(struct fec_enet_private *fep,`
`296`	`296`	`entries = ((const char *)txq->dirty_tx -`
`297`	`297`	`(const char *)txq->cur_tx) / fep->bufdesc_size - 1;`
`298`	`298`
`299`		`- return entries > 0 ? entries : entries + txq->tx_ring_size;`
	`299`	`+ return entries >= 0 ? entries : entries + txq->tx_ring_size;`
`300`	`300`	`}`
`301`	`301`
`302`	`302`	`static void swap_buffer(void *bufaddr, int len)`