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-rw-r--r--include/linux/init_task.h1
-rw-r--r--include/linux/prctl.h7
-rw-r--r--include/linux/sched.h6
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/sys.c10
5 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 021d8e7..23fd890 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -170,6 +170,7 @@ extern struct group_info init_groups;
.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
.fs_excl = ATOMIC_INIT(0), \
.pi_lock = __SPIN_LOCK_UNLOCKED(tsk.pi_lock), \
+ .timer_slack_ns = 50000, /* 50 usec default slack */ \
.pids = { \
[PIDTYPE_PID] = INIT_PID_LINK(PIDTYPE_PID), \
[PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID), \
diff --git a/include/linux/prctl.h b/include/linux/prctl.h
index 5ad7919..48d887e 100644
--- a/include/linux/prctl.h
+++ b/include/linux/prctl.h
@@ -78,4 +78,11 @@
#define PR_GET_SECUREBITS 27
#define PR_SET_SECUREBITS 28
+/*
+ * Get/set the timerslack as used by poll/select/nanosleep
+ * A value of 0 means "use default"
+ */
+#define PR_SET_TIMERSLACK 29
+#define PR_GET_TIMERSLACK 30
+
#endif /* _LINUX_PRCTL_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3d9120c..dcc03fd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1301,6 +1301,12 @@ struct task_struct {
int latency_record_count;
struct latency_record latency_record[LT_SAVECOUNT];
#endif
+ /*
+ * time slack values; these are used to round up poll() and
+ * select() etc timeout values. These are in nanoseconds.
+ */
+ unsigned long timer_slack_ns;
+ unsigned long default_timer_slack_ns;
};
/*
diff --git a/kernel/fork.c b/kernel/fork.c
index 7ce2ebe..4308d75 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -987,6 +987,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->prev_utime = cputime_zero;
p->prev_stime = cputime_zero;
+ p->default_timer_slack_ns = current->timer_slack_ns;
+
#ifdef CONFIG_DETECT_SOFTLOCKUP
p->last_switch_count = 0;
p->last_switch_timestamp = 0;
diff --git a/kernel/sys.c b/kernel/sys.c
index 038a7bc..1b96401 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1727,6 +1727,16 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
case PR_SET_TSC:
error = SET_TSC_CTL(arg2);
break;
+ case PR_GET_TIMERSLACK:
+ error = current->timer_slack_ns;
+ break;
+ case PR_SET_TIMERSLACK:
+ if (arg2 <= 0)
+ current->timer_slack_ns =
+ current->default_timer_slack_ns;
+ else
+ current->timer_slack_ns = arg2;
+ break;
default:
error = -EINVAL;
break;
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