| Message ID | 20220623165552.38645-1-logang@deltatee.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | md/raid5: Fix divide type in raid5_make_request() | expand |
On Thu, Jun 23, 2022 at 9:56 AM Logan Gunthorpe <logang@deltatee.com> wrote: > > 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? Thanks, Song > > Fixes: 681fb14a7100 ("md/raid5: Pivot raid5_make_request()") > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Logan Gunthorpe <logang@deltatee.com> > --- > drivers/md/raid5.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c > index 5723a497108a..9d25696b793d 100644 > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -6091,7 +6091,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) > bi->bi_next = NULL; > > bitmap_set(ctx.sectors_to_do, 0, > - DIV_ROUND_UP(ctx.last_sector - logical_sector, > + DIV_ROUND_UP((int)(ctx.last_sector - logical_sector), > RAID5_STRIPE_SECTORS(conf))); > > pr_debug("raid456: %s, logical %llu to %llu\n", __func__, > > base-commit: 57c19f921f8081c1a9444dc7f3f6b3ea43fe612e > -- > 2.30.2 >
On 2022-06-23 11:15, Song Liu wrote: > On Thu, Jun 23, 2022 at 9:56 AM Logan Gunthorpe <logang@deltatee.com> wrote: >> >> 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
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 5723a497108a..9d25696b793d 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -6091,7 +6091,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) bi->bi_next = NULL; bitmap_set(ctx.sectors_to_do, 0, - DIV_ROUND_UP(ctx.last_sector - logical_sector, + DIV_ROUND_UP((int)(ctx.last_sector - logical_sector), RAID5_STRIPE_SECTORS(conf))); pr_debug("raid456: %s, logical %llu to %llu\n", __func__,
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. Fixes: 681fb14a7100 ("md/raid5: Pivot raid5_make_request()") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Logan Gunthorpe <logang@deltatee.com> --- drivers/md/raid5.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) base-commit: 57c19f921f8081c1a9444dc7f3f6b3ea43fe612e