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

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?