drivers/target/target_core_transport.c breakage on i386

drivers/target/target_core_transport.c breakage on i386

[Al Viro]

In commit ec98f7825c6eaa4a9afb0eb518826efc8a2ed4a2
Author: Andy Grover <agrover@redhat.com>
Date:   Wed Jul 20 19:28:46 2011 +0000

    target: Eliminate usage of struct se_mem

we got
+       task_count = DIV_ROUND_UP(sectors, dev_max_sectors);
and that's sector_t/sector_t.  64bit division on i386 is no-no in
the kernel - it emits __udivdi3 call and it's not there.  Can
sectors really reach 2^32 here?

Re: drivers/target/target_core_transport.c breakage on i386

[Nicholas A. Bellinger]

On Mon, 2011-08-08 at 01:10 +0100, Al Viro wrote:
> In commit ec98f7825c6eaa4a9afb0eb518826efc8a2ed4a2
> Author: Andy Grover <agrover@redhat.com>
> Date:   Wed Jul 20 19:28:46 2011 +0000
> 
>     target: Eliminate usage of struct se_mem
> 
> we got
> +       task_count = DIV_ROUND_UP(sectors, dev_max_sectors);
> and that's sector_t/sector_t.  64bit division on i386 is no-no in
> the kernel - it emits __udivdi3 call and it's not there.  Can
> sectors really reach 2^32 here?
> 

Hi Al,

Just a heads up that this was caught this before -rc1, and we ended up
adding DIV_ROUND_UP_ULL using do_div() for the 32-bit case here, and
another DIV_ROUND_UP_SECTOR_T macro that target_core_transport.c is now
using to address this for i386.

kernel.h: Add DIV_ROUND_UP_ULL and DIV_ROUND_UP_SECTOR_T macro usage
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=36a26c69b4c70396ef569c3452690fba0c1dec08

Thanks,

--nab