[PATCH v2] drivers: net: xgene: Rewrite loop in xgene_enet_ecc_init()

drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c: In function ‘xgene_enet_ecc_init’:
drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c:126: warning: ‘data’ may be used uninitialized in this function

Depending on the arbitrary value on the stack, the loop may terminate
too early, and cause a bogus -ENODEV failure.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2: Rewrite the loop instead of pre-initializing data.

 drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c b/drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c
index e6d24c2101982444..2a497b38ed420495 100644
--- a/drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c
+++ b/drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c

@@ -127,17 +127,15 @@ static int xgene_enet_ecc_init(struct xgene_enet_pdata *p)
 	int i;
 
 	xgene_enet_wr_diag_csr(p, ENET_CFG_MEM_RAM_SHUTDOWN_ADDR, 0);
-	for (i = 0; i < 10 && data != ~0U ; i++) {
+	for (i = 0; i < 10; i++) {
 		usleep_range(100, 110);
 		data = xgene_enet_rd_diag_csr(p, ENET_BLOCK_MEM_RDY_ADDR);
+		if (data == ~0U)
+			return 0;
 	}
 
-	if (data != ~0U) {
-		netdev_err(ndev, "Failed to release memory from shutdown\n");
-		return -ENODEV;
-	}
-
-	return 0;
+	netdev_err(ndev, "Failed to release memory from shutdown\n");
+	return -ENODEV;
 }
 
 static void xgene_enet_config_ring_if_assoc(struct xgene_enet_pdata *p)

-- 
1.9.1

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 09:39:41 +0200

drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c: In function ‘xgene_enet_ecc_init’:
drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c:126: warning: ‘data’ may be used uninitialized in this function

Depending on the arbitrary value on the stack, the loop may terminate
too early, and cause a bogus -ENODEV failure.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2: Rewrite the loop instead of pre-initializing data.

I hate to be a pest, but like the other patch of your's I think
a do { } while() works best here because the intent is clearly
to run the loop at least once, right?

On Wed, Oct 22, 2014 at 9:34 PM, David Miller [off-list ref] wrote:

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 09:39:41 +0200

quoted

drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c: In function ‘xgene_enet_ecc_init’:
drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c:126: warning: ‘data’ may be used uninitialized in this function

Depending on the arbitrary value on the stack, the loop may terminate
too early, and cause a bogus -ENODEV failure.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2: Rewrite the loop instead of pre-initializing data.

I hate to be a pest, but like the other patch of your's I think
a do { } while() works best here because the intent is clearly
to run the loop at least once, right?

I wanted to avoid checking for "data != ~0U" twice: once to abort the loop,
and once to check if a timeout happened.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 21:50:06 +0200

On Wed, Oct 22, 2014 at 9:34 PM, David Miller [off-list ref] wrote:

quoted

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 09:39:41 +0200

quoted

drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c: In function ‘xgene_enet_ecc_init’:
drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c:126: warning: ‘data’ may be used uninitialized in this function

Depending on the arbitrary value on the stack, the loop may terminate
too early, and cause a bogus -ENODEV failure.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2: Rewrite the loop instead of pre-initializing data.

I hate to be a pest, but like the other patch of your's I think
a do { } while() works best here because the intent is clearly
to run the loop at least once, right?

I wanted to avoid checking for "data != ~0U" twice: once to abort the loop,
and once to check if a timeout happened.

Hmmm:

	do {
		usleep_range(...);
		data = ...();
		if (data == ~0)
			return 0;
	} while (++i < 10);

	netdev_err(...);
	return -ENODEV;

Why would you have to check data twice?

On Wed, Oct 22, 2014 at 10:12 PM, David Miller [off-list ref] wrote:

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 21:50:06 +0200

quoted

On Wed, Oct 22, 2014 at 9:34 PM, David Miller [off-list ref] wrote:

quoted

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 09:39:41 +0200

quoted

drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c: In function ‘xgene_enet_ecc_init’:
drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c:126: warning: ‘data’ may be used uninitialized in this function

Depending on the arbitrary value on the stack, the loop may terminate
too early, and cause a bogus -ENODEV failure.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2: Rewrite the loop instead of pre-initializing data.

I hate to be a pest, but like the other patch of your's I think
a do { } while() works best here because the intent is clearly
to run the loop at least once, right?

I wanted to avoid checking for "data != ~0U" twice: once to abort the loop,
and once to check if a timeout happened.

Hmmm:

        do {
                usleep_range(...);
                data = ...();
                if (data == ~0)
                        return 0;
        } while (++i < 10);

        netdev_err(...);
        return -ENODEV;

Why would you have to check data twice?

-- 
Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

On Wed, Oct 22, 2014 at 10:12 PM, David Miller [off-list ref] wrote:

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 21:50:06 +0200

quoted

On Wed, Oct 22, 2014 at 9:34 PM, David Miller [off-list ref] wrote:

quoted

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed, 22 Oct 2014 09:39:41 +0200

quoted

drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c: In function ‘xgene_enet_ecc_init’:
drivers/net/ethernet/apm/xgene/xgene_enet_sgmac.c:126: warning: ‘data’ may be used uninitialized in this function

Depending on the arbitrary value on the stack, the loop may terminate
too early, and cause a bogus -ENODEV failure.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
v2: Rewrite the loop instead of pre-initializing data.

I hate to be a pest, but like the other patch of your's I think
a do { } while() works best here because the intent is clearly
to run the loop at least once, right?

I wanted to avoid checking for "data != ~0U" twice: once to abort the loop,
and once to check if a timeout happened.

Hmmm:

        do {
                usleep_range(...);
                data = ...();
                if (data == ~0)
                        return 0;
        } while (++i < 10);

        netdev_err(...);
        return -ENODEV;

Why would you have to check data twice?

Yes, that would work to.

Feel free to do s/for (i = 0; i < 10; i++)/do/ and s/}/} while (++i < 10);/

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds