i8253.c (7483d45f0aee3afc0646d185cabd4af9f6cab58c) i8253.c (d6ad418763888f617ac5b4849823e4cd670df1dd)
1/*
2 * i8253 PIT clocksource
3 */
4#include <linux/clockchips.h>
5#include <linux/init.h>
6#include <linux/io.h>
7#include <linux/spinlock.h>
8#include <linux/timex.h>

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30 static int old_count;
31 static u32 old_jifs;
32 unsigned long flags;
33 int count;
34 u32 jifs;
35
36 raw_spin_lock_irqsave(&i8253_lock, flags);
37 /*
1/*
2 * i8253 PIT clocksource
3 */
4#include <linux/clockchips.h>
5#include <linux/init.h>
6#include <linux/io.h>
7#include <linux/spinlock.h>
8#include <linux/timex.h>

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30 static int old_count;
31 static u32 old_jifs;
32 unsigned long flags;
33 int count;
34 u32 jifs;
35
36 raw_spin_lock_irqsave(&i8253_lock, flags);
37 /*
38 * Although our caller may have the read side of xtime_lock,
38 * Although our caller may have the read side of jiffies_lock,
39 * this is now a seqlock, and we are cheating in this routine
40 * by having side effects on state that we cannot undo if
41 * there is a collision on the seqlock and our caller has to
42 * retry. (Namely, old_jifs and old_count.) So we must treat
43 * jiffies as volatile despite the lock. We read jiffies
44 * before latching the timer count to guarantee that although
45 * the jiffies value might be older than the count (that is,
46 * the counter may underflow between the last point where

--- 140 unchanged lines hidden --- 		39 * this is now a seqlock, and we are cheating in this routine
40 * by having side effects on state that we cannot undo if
41 * there is a collision on the seqlock and our caller has to
42 * retry. (Namely, old_jifs and old_count.) So we must treat
43 * jiffies as volatile despite the lock. We read jiffies
44 * before latching the timer count to guarantee that although
45 * the jiffies value might be older than the count (that is,
46 * the counter may underflow between the last point where

--- 140 unchanged lines hidden ---