2015-11-20 16:42:50

by Arnd Bergmann

Subject: [PATCH] IB/iser: use sector_div instead of do_div

do_div is the wrong way to divide a sector_t, as it is less
efficient when sector_t is 32-bit wide. With the upcoming
do_div optimizations, the kernel starts warning about this:

drivers/infiniband/ulp/iser/iser_verbs.c:1296:4: note: in expansion of macro 'do_div'
include/asm-generic/div64.h:224:22: warning: passing argument 1 of '__div64_32' from incompatible pointer type

This changes the code to use sector_div instead, which always
produces optimal code.

Signed-off-by: Arnd Bergmann <[email protected]>

diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c
index a93070210109..42f4da620f2e 100644
--- a/drivers/infiniband/ulp/iser/iser_verbs.c
+++ b/drivers/infiniband/ulp/iser/iser_verbs.c
@@ -1293,7 +1293,7 @@ u8 iser_check_task_pi_status(struct iscsi_iser_task *iser_task,
if (mr_status.fail_status & IB_MR_CHECK_SIG_STATUS) {
sector_t sector_off = mr_status.sig_err.sig_err_offset;

- do_div(sector_off, sector_size + 8);
+ sector_div(sector_off, sector_size + 8);
*sector = scsi_get_lba(iser_task->sc) + sector_off;

pr_err("PI error found type %d at sector %llx "

2015-11-21 02:18:22

by Sagi Grimberg

Subject: Re: [PATCH] IB/iser: use sector_div instead of do_div

> do_div is the wrong way to divide a sector_t, as it is less
> efficient when sector_t is 32-bit wide. With the upcoming
> do_div optimizations, the kernel starts warning about this:
>
> drivers/infiniband/ulp/iser/iser_verbs.c:1296:4: note: in expansion of macro 'do_div'
> include/asm-generic/div64.h:224:22: warning: passing argument 1 of '__div64_32' from incompatible pointer type
>
> This changes the code to use sector_div instead, which always
> produces optimal code.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Thanks Arnd,

Reviewed-by: Sagi Grimberg <[email protected]>