x86: vdso: Use seqcount instead of seqlock

The update of the vdso data happens under xtime_lock, so adding a
nested lock is pointless. Just use a seqcount to sync the readers.

Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 8 insertions, 8 deletions

diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index 7eeb1f6188e..944c5e5d6b6 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -100,12 +100,12 @@ notrace static noinline int do_realtime(struct timespec *ts)
         int mode;
 
         do {
-                seq = read_seqbegin(&gtod->lock);
+                seq = read_seqcount_begin(&gtod->seq);
                 mode = gtod->clock.vclock_mode;
                 ts->tv_sec = gtod->wall_time_sec;
                 ts->tv_nsec = gtod->wall_time_nsec;
                 ns = vgetns();
-        } while (unlikely(read_seqretry(&gtod->lock, seq)));
+        } while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
 
         timespec_add_ns(ts, ns);
         return mode;
@@ -117,13 +117,13 @@ notrace static noinline int do_monotonic(struct timespec *ts)
         int mode;
 
         do {
-                seq = read_seqbegin(&gtod->lock);
+                seq = read_seqcount_begin(&gtod->seq);
                 mode = gtod->clock.vclock_mode;
                 secs = gtod->wall_time_sec;
                 ns = gtod->wall_time_nsec + vgetns();
                 secs += gtod->wall_to_monotonic.tv_sec;
                 ns += gtod->wall_to_monotonic.tv_nsec;
-        } while (unlikely(read_seqretry(&gtod->lock, seq)));
+        } while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
 
         /* wall_time_nsec, vgetns(), and wall_to_monotonic.tv_nsec
          * are all guaranteed to be nonnegative.
@@ -142,10 +142,10 @@ notrace static noinline int do_realtime_coarse(struct timespec *ts)
 {
         unsigned long seq;
         do {
-                seq = read_seqbegin(&gtod->lock);
+                seq = read_seqcount_begin(&gtod->seq);
                 ts->tv_sec = gtod->wall_time_coarse.tv_sec;
                 ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
-        } while (unlikely(read_seqretry(&gtod->lock, seq)));
+        } while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
         return 0;
 }
 
@@ -153,12 +153,12 @@ notrace static noinline int do_monotonic_coarse(struct timespec *ts)
 {
         unsigned long seq, ns, secs;
         do {
-                seq = read_seqbegin(&gtod->lock);
+                seq = read_seqcount_begin(&gtod->seq);
                 secs = gtod->wall_time_coarse.tv_sec;
                 ns = gtod->wall_time_coarse.tv_nsec;
                 secs += gtod->wall_to_monotonic.tv_sec;
                 ns += gtod->wall_to_monotonic.tv_nsec;
-        } while (unlikely(read_seqretry(&gtod->lock, seq)));
+        } while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
 
         /* wall_time_nsec and wall_to_monotonic.tv_nsec are
          * guaranteed to be between 0 and NSEC_PER_SEC.