[PATCH] dpaa_eth: avoid uninitialized variable false-positive warning

[PATCH] dpaa_eth: avoid uninitialized variable false-positive warning

[Arnd Bergmann]

We can now build this driver on ARM, so I ran into a randconfig build
warning that presumably had existed on powerpc already.

drivers/net/ethernet/freescale/dpaa/dpaa_eth.c: In function 'sg_fd_to_skb':
drivers/net/ethernet/freescale/dpaa/dpaa_eth.c:1712:18: error: 'skb' may be used uninitialized in this function [-Werror=maybe-uninitialized]

I'm slightly changing the logic here, to make it obvious to the
compiler that 'skb' is always initialized.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
index 969f6b12952e..ebc55b6a6349 100644
--- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
@@ -1721,6 +1721,7 @@ static struct sk_buff *sg_fd_to_skb(const struct dpaa_priv *priv,
 
 	/* Iterate through the SGT entries and add data buffers to the skb */
 	sgt = vaddr + fd_off;
+	skb = NULL;
 	for (i = 0; i < DPAA_SGT_MAX_ENTRIES; i++) {
 		/* Extension bit is not supported */
 		WARN_ON(qm_sg_entry_is_ext(&sgt[i]));
@@ -1738,7 +1739,7 @@ static struct sk_buff *sg_fd_to_skb(const struct dpaa_priv *priv,
 		count_ptr = this_cpu_ptr(dpaa_bp->percpu_count);
 		dma_unmap_single(dpaa_bp->dev, sg_addr, dpaa_bp->size,
 				 DMA_FROM_DEVICE);
-		if (i == 0) {
+		if (!skb) {
 			sz = dpaa_bp->size +
 				SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 			skb = build_skb(sg_vaddr, sz);
-- 
2.9.0

Re: [PATCH] dpaa_eth: avoid uninitialized variable false-positive warning

[David Miller]

From: Arnd Bergmann <arnd@arndb.de>
Date: Fri,  3 Nov 2017 13:52:24 +0100

> We can now build this driver on ARM, so I ran into a randconfig build
> warning that presumably had existed on powerpc already.
> 
> drivers/net/ethernet/freescale/dpaa/dpaa_eth.c: In function 'sg_fd_to_skb':
> drivers/net/ethernet/freescale/dpaa/dpaa_eth.c:1712:18: error: 'skb' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> I'm slightly changing the logic here, to make it obvious to the
> compiler that 'skb' is always initialized.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Applied, thanks.