sched_clock: Expose struct clock_read_data

[linux-2.6-microblaze.git] / kernel / time / sched_clock.c

diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index fa3f800..0acaadc 100644 (file)
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -19,31 +19,6 @@
 
 #include "timekeeping.h"
 
-/**
- * struct clock_read_data - data required to read from sched_clock()
- *
- * @epoch_ns:          sched_clock() value at last update
- * @epoch_cyc:         Clock cycle value at last update.
- * @sched_clock_mask:   Bitmask for two's complement subtraction of non 64bit
- *                     clocks.
- * @read_sched_clock:  Current clock source (or dummy source when suspended).
- * @mult:              Multipler for scaled math conversion.
- * @shift:             Shift value for scaled math conversion.
- *
- * Care must be taken when updating this structure; it is read by
- * some very hot code paths. It occupies <=40 bytes and, when combined
- * with the seqcount used to synchronize access, comfortably fits into
- * a 64 byte cache line.
- */
-struct clock_read_data {
-       u64 epoch_ns;
-       u64 epoch_cyc;
-       u64 sched_clock_mask;
-       u64 (*read_sched_clock)(void);
-       u32 mult;
-       u32 shift;
-};
-
 /**
  * struct clock_data - all data needed for sched_clock() (including
  *                     registration of a new clock source)
@@ -93,6 +68,17 @@ static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
        return (cyc * mult) >> shift;
 }
 
+struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
+{
+       *seq = raw_read_seqcount(&cd.seq);
+       return cd.read_data + (*seq & 1);
+}
+
+int sched_clock_read_retry(unsigned int seq)
+{
+       return read_seqcount_retry(&cd.seq, seq);
+}
+
 unsigned long long notrace sched_clock(void)
 {
        u64 cyc, res;
@@ -100,13 +86,12 @@ unsigned long long notrace sched_clock(void)
        struct clock_read_data *rd;
 
        do {
-               seq = raw_read_seqcount(&cd.seq);
-               rd = cd.read_data + (seq & 1);
+               rd = sched_clock_read_begin(&seq);
 
                cyc = (rd->read_sched_clock() - rd->epoch_cyc) &
                      rd->sched_clock_mask;
                res = rd->epoch_ns + cyc_to_ns(cyc, rd->mult, rd->shift);
-       } while (read_seqcount_retry(&cd.seq, seq));
+       } while (sched_clock_read_retry(seq));
 
        return res;
 }