[PATCH 08/16] tsacct: add 64-bit btime field

Arnd Bergmann
2019-11-08T21:36:01Z

As there is only a 32-bit ac_btime field in taskstat and
we should handle dates after the overflow, add a new field
with the same information but 64-bit width that can hold
a full time64_t.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
include/uapi/linux/taskstats.h | 5 ++++-
kernel/tsacct.c | 1 +
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/taskstats.h b/include/uapi/linux/taskstats.h
index 7d3ea366e93b..ccbd08709321 100644
--- a/include/uapi/linux/taskstats.h
+++ b/include/uapi/linux/taskstats.h
@@ -34,7 +34,7 @@
*/

-#define TASKSTATS_VERSION 9
+#define TASKSTATS_VERSION 10
#define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN
* in linux/sched.h */

@@ -169,6 +169,9 @@ struct taskstats {
/* Delay waiting for thrashing page */
__u64 thrashing_count;
__u64 thrashing_delay_total;
+
+ /* v10: 64-bit btime to avoid overflow */
+ __u64 ac_btime64; /* 64-bit begin time */
};

diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index ab12616ee6fb..257ffb993ea2 100644
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -36,6 +36,7 @@ void bacct_add_tsk(struct user_namespace *user_ns,
/* Convert to seconds for btime (note y2106 limit) */
btime = ktime_get_real_seconds() - div_u64(delta, USEC_PER_SEC);
stats->ac_btime = clamp_t(time64_t, btime, 0, U32_MAX);
+ stats->ac_btime64 = btime;

if (thread_group_leader(tsk)) {
stats->ac_exitcode = tsk->exit_code;
--
2.20.0