timekeeping: Convert jiffies_seq to seqcount_raw_spinlock_t

Use the new api and associate the seqcounter to the jiffies_lock enabling
lockdep support - although for this particular case the write-side locking
and non-preemptibility are quite obvious.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201021190749.19363-1-dave@stgolabs.net

kernel/time/jiffies.c

@@ -59,7 +59,8 @@ static struct clocksource clocksource_jiffies = {
 };
 
 __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(jiffies_lock);
-__cacheline_aligned_in_smp seqcount_t jiffies_seq;
+__cacheline_aligned_in_smp seqcount_raw_spinlock_t jiffies_seq =
+	SEQCNT_RAW_SPINLOCK_ZERO(jiffies_seq, &jiffies_lock);
 
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void)

kernel/time/timekeeping.h

@@ -26,7 +26,7 @@ extern void do_timer(unsigned long ticks);
 extern void update_wall_time(void);
 
 extern raw_spinlock_t jiffies_lock;
-extern seqcount_t jiffies_seq;
+extern seqcount_raw_spinlock_t jiffies_seq;
 
 #define CS_NAME_LEN	32