On 2022-06-23 11:15, Song Liu wrote:

On Thu, Jun 23, 2022 at 9:56 AM Logan Gunthorpe [off-list ref] wrote:

quoted

0day reports a build failure on the hexagon architecture:

  ld.lld: error: undefined symbol: __hexagon_udivdi3
     referenced by raid5.c
        md/raid5.o:(raid5_make_request) in archive drivers/built-in.a
     referenced by raid5.c
        md/raid5.o:(raid5_make_request) in archive drivers/built-in.a
     did you mean: __hexagon_udivsi3
        defined in: arch/hexagon/built-in.a(lib/udivsi3.o)

This is caused by using DIV_ROUND_UP on a sector_t type.

The actual value is known to be less than 256 so a wide 64bit divide
here is not desirable. Thus cast the argument to an int to ensure it
uses a 32bit divide.

I force pushed an update that uses DIV_ROUND_UP_SECTOR_T instead.
I guess that should also work?

Ah, yes, that'll also fix the bug. I chose to cast to minimize the
performance impact of an unnecessarily wide divide. But I don't have any
strong basis to suggest the performance will be worse with the wider
division. So fix it whichever way you think is best.

Logan