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SubjectRe: [PATCH] zcache: Use div_u64 for 64-bit division
On Thu,  4 Aug 2011 19:00:33 -0300 Thadeu Lima de Souza Cascardo wrote:

> xv_get_total_size_bytes returns a u64 value and it's used in a division.
> This causes build failures in 32-bit architectures, as reported by Randy
> Dunlap.
>
> Reported-by: Randy Dunlap <rdunlap@xenotime.net>
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
> Cc: Stephen Rothwell <sfr@canb.auug.org.au>
> Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
> Cc: Nitin Gupta <ngupta@vflare.org>
> Cc: Greg KH <greg@kroah.com>
> Cc: driverdevel <devel@driverdev.osuosl.org>
> Cc: linux-next@vger.kernel.org
> Cc: LKML <linux-kernel@vger.kernel.org>

Acked-by: Randy Dunlap <rdunlap@xenotime.net>

Thanks.

> ---
> drivers/staging/zcache/zcache-main.c | 7 +++++--
> 1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
> index 66469ac..2c41c44 100644
> --- a/drivers/staging/zcache/zcache-main.c
> +++ b/drivers/staging/zcache/zcache-main.c
> @@ -28,6 +28,7 @@
> #include <linux/spinlock.h>
> #include <linux/types.h>
> #include <linux/atomic.h>
> +#include <linux/math64.h>
> #include "tmem.h"
>
> #include "../zram/xvmalloc.h" /* if built in drivers/staging */
> @@ -1162,6 +1163,7 @@ static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph,
> uint16_t client_id = get_client_id_from_client(cli);
> unsigned long zv_mean_zsize;
> unsigned long curr_pers_pampd_count;
> + u64 total_zsize;
>
> if (eph) {
> ret = zcache_compress(page, &cdata, &clen);
> @@ -1194,8 +1196,9 @@ static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph,
> }
> /* reject if mean compression is too poor */
> if ((clen > zv_max_mean_zsize) && (curr_pers_pampd_count > 0)) {
> - zv_mean_zsize = xv_get_total_size_bytes(cli->xvpool) /
> - curr_pers_pampd_count;
> + total_zsize = xv_get_total_size_bytes(cli->xvpool);
> + zv_mean_zsize = div_u64(total_zsize,
> + curr_pers_pampd_count);
> if (zv_mean_zsize > zv_max_mean_zsize) {
> zcache_mean_compress_poor++;
> goto out;
> --


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


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