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authorArnd Bergmann <arnd@arndb.de>2015-11-25 16:16:55 +0100
committerTejun Heo <tj@kernel.org>2015-11-25 14:00:05 -0500
commitd2b4365809060b256330a99289de9797a5dd6967 (patch)
tree9365cd0791b20332059ec044962314f152ff4c46 /kernel/cpuset.c
parent6c2920926b10e8303378408e3c2b8952071d4344 (diff)
downloadlwn-d2b4365809060b256330a99289de9797a5dd6967.tar.gz
lwn-d2b4365809060b256330a99289de9797a5dd6967.zip
cpuset: Replace all instances of time_t with time64_t
The following patch replaces all instances of time_t with time64_t i.e. change the type used for representing time from 32-bit to 64-bit. All 32-bit kernels to date use a signed 32-bit time_t type, which can only represent time until January 2038. Since embedded systems running 32-bit Linux are going to survive beyond that date, we have to change all current uses, in a backwards compatible way. The patch also changes the function get_seconds() that returns a 32-bit integer to ktime_get_seconds() that returns seconds as 64-bit integer. The patch changes the type of ticks from time_t to u32. We keep ticks as 32-bits as the function uses 32-bit arithmetic which would prove less expensive than 64-bit arithmetic and the function is expected to be called atleast once every 32 seconds. Signed-off-by: Heena Sirwani <heenasirwani@gmail.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 10ae73611d80..c9ea63ff70a7 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -51,6 +51,7 @@
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/time.h>
+#include <linux/time64.h>
#include <linux/backing-dev.h>
#include <linux/sort.h>
@@ -68,7 +69,7 @@ struct static_key cpusets_enabled_key __read_mostly = STATIC_KEY_INIT_FALSE;
struct fmeter {
int cnt; /* unprocessed events count */
int val; /* most recent output value */
- time_t time; /* clock (secs) when val computed */
+ time64_t time; /* clock (secs) when val computed */
spinlock_t lock; /* guards read or write of above */
};
@@ -1374,7 +1375,7 @@ out:
*/
#define FM_COEF 933 /* coefficient for half-life of 10 secs */
-#define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
+#define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */
#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
#define FM_SCALE 1000 /* faux fixed point scale */
@@ -1390,8 +1391,11 @@ static void fmeter_init(struct fmeter *fmp)
/* Internal meter update - process cnt events and update value */
static void fmeter_update(struct fmeter *fmp)
{
- time_t now = get_seconds();
- time_t ticks = now - fmp->time;
+ time64_t now;
+ u32 ticks;
+
+ now = ktime_get_seconds();
+ ticks = now - fmp->time;
if (ticks == 0)
return;