Re: [PATCH] staging: goldfish: use div64_s64 instead of do_div

[One Thousand Gnomes]

On Mon, 01 Feb 2016 11:33 +0100
Arnd Bergmann <arnd@xxxxxxxx> wrote:

> The goldfish nand driver divides a signed 64-bit number (loff_t)
> in multiple places using the do_div() function. This has always
> been unreliable but now produces a compiler warning (since 4.5-rc1):
> 
> goldfish/goldfish_nand.c: In function 'goldfish_nand_erase':
> goldfish/goldfish_nand.c:107:91: error: comparison of distinct pointer types lacks a cast [-Werror]
> goldfish/goldfish_nand.c: In function 'goldfish_nand_read_oob':
> goldfish/goldfish_nand.c:145:91: error: comparison of distinct pointer types lacks a cast [-Werror]
> 
> This changes the code to the equivalent div_s64{,_rem} that
> works correctly for negative numbers (which we should never
> get here).

We can't get negatives as you say so surely the right fix is a cast or to
fix mtd->writesize ?