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SubjectRe: [PATCH] blkio-throttle: Fix linux-next compilation failure on i386
On 09/28/10 12:34, Vivek Goyal wrote:
> Hi Jens,
>
> One more fix for throttling logic. After this fix I realized that there is
> potential for integer overflow in my calculations. I need to figure out
> how to take care of these overflow situations and will post a patch for
> that later.
>
> Thanks
> Vivek
>
> o Randy Dunlap reported following linux-next failure. This patch fixes it.
>
> on i386:
>
> blk-throttle.c:(.text+0x1abb8): undefined reference to `__udivdi3'
> blk-throttle.c:(.text+0x1b1dc): undefined reference to `__udivdi3'
>
> o bytes_per_second interface is 64bit and I was continuing to do 64 bit
> division even on 32bit platform without help of special macros/functions
> hence the failure.
>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>

Acked-by: Randy Dunlap <randy.dunlap@oracle.com>

Thanks.

> ---
> block/blk-throttle.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> Index: linux-2.6-block/block/blk-throttle.c
> ===================================================================
> --- linux-2.6-block.orig/block/blk-throttle.c 2010-09-28 12:42:51.000000000 -0400
> +++ linux-2.6-block/block/blk-throttle.c 2010-09-28 14:16:05.000000000 -0400
> @@ -378,7 +378,8 @@ throtl_slice_used(struct throtl_data *td
> static inline void
> throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
> {
> - unsigned long nr_slices, bytes_trim, time_elapsed, io_trim;
> + unsigned long nr_slices, time_elapsed, io_trim;
> + u64 bytes_trim, tmp;
>
> BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
>
> @@ -396,8 +397,10 @@ throtl_trim_slice(struct throtl_data *td
>
> if (!nr_slices)
> return;
> + tmp = tg->bps[rw] * throtl_slice * nr_slices;
> + do_div(tmp, HZ);
> + bytes_trim = tmp;
>
> - bytes_trim = (tg->bps[rw] * throtl_slice * nr_slices)/HZ;
> io_trim = (tg->iops[rw] * throtl_slice * nr_slices)/HZ;
>
> if (!bytes_trim && !io_trim)
> @@ -415,7 +418,7 @@ throtl_trim_slice(struct throtl_data *td
>
> tg->slice_start[rw] += nr_slices * throtl_slice;
>
> - throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%lu io=%lu"
> + throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
> " start=%lu end=%lu jiffies=%lu",
> rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
> tg->slice_start[rw], tg->slice_end[rw], jiffies);
> @@ -462,7 +465,7 @@ static bool tg_with_in_bps_limit(struct
> struct bio *bio, unsigned long *wait)
> {
> bool rw = bio_data_dir(bio);
> - u64 bytes_allowed, extra_bytes;
> + u64 bytes_allowed, extra_bytes, tmp;
> unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
>
> jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
> @@ -473,8 +476,9 @@ static bool tg_with_in_bps_limit(struct
>
> jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
>
> - bytes_allowed = (tg->bps[rw] * jiffies_to_msecs(jiffy_elapsed_rnd))
> - / MSEC_PER_SEC;
> + tmp = tg->bps[rw] * jiffies_to_msecs(jiffy_elapsed_rnd);
> + do_div(tmp, MSEC_PER_SEC);
> + bytes_allowed = tmp;
>
> if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) {
> if (wait)


--
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***


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