timekeeping: Add persistent_clock_exist flag

In current kernel, there are several places which need to check whether there is a persistent clock for the platform. Current check is done by calling the read_persistent_clock() and validating its return value. So one optimization is to do the check only once in timekeeping_init(), and use a flag persistent_clock_exist to record it. v2: Add a has_persistent_clock() helper function, as suggested by John.

Feng Tang committed 13 years ago

Commit 31ade301 parent f0dbe812 files · +17 −5Browse files

Showing the changes to include/linux (1 of 2 files). Show all

Unified · Split

include/linux/time.h+6−0

@@ -115,6 +115,12 @@ static inline bool timespec_valid_strict(const struct timespec *ts) · 114 unmodified lines
115	115	return true;
116	116	}
117	117
	118	+extern bool persistent_clock_exist;
	119	+static inline bool has_persistent_clock(void)
	120	+{
	121	+ return persistent_clock_exist;
	122	+}
	123	+
118	124	extern void read_persistent_clock(struct timespec *ts);
119	125	extern void read_boot_clock(struct timespec *ts);
120	126	extern int update_persistent_clock(struct timespec now);