[linux.git] / arch / x86 / xen / spinlock.c

/*
 * Split spinlock implementation out into its own file, so it can be
 * compiled in a FTRACE-compatible way.
 */
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/log2.h>
#include <linux/gfp.h>

#include <asm/paravirt.h>

#include <xen/interface/xen.h>
#include <xen/events.h>

#include "xen-ops.h"
#include "debugfs.h"

#ifdef CONFIG_XEN_DEBUG_FS
static struct xen_spinlock_stats
{
	u64 taken;
	u32 taken_slow;
	u32 taken_slow_nested;
	u32 taken_slow_pickup;
	u32 taken_slow_spurious;
	u32 taken_slow_irqenable;

	u64 released;
	u32 released_slow;
	u32 released_slow_kicked;

#define HISTO_BUCKETS	30
	u32 histo_spin_total[HISTO_BUCKETS+1];
	u32 histo_spin_spinning[HISTO_BUCKETS+1];
	u32 histo_spin_blocked[HISTO_BUCKETS+1];

	u64 time_total;
	u64 time_spinning;
	u64 time_blocked;
} spinlock_stats;

static u8 zero_stats;

static unsigned lock_timeout = 1 << 10;
#define TIMEOUT lock_timeout

static inline void check_zero(void)
{
	if (unlikely(zero_stats)) {
		memset(&spinlock_stats, 0, sizeof(spinlock_stats));
		zero_stats = 0;
	}
}

#define ADD_STATS(elem, val)			\
	do { check_zero(); spinlock_stats.elem += (val); } while(0)

static inline u64 spin_time_start(void)
{
	return xen_clocksource_read();
}

static void __spin_time_accum(u64 delta, u32 *array)
{
	unsigned index = ilog2(delta);

	check_zero();

	if (index < HISTO_BUCKETS)
		array[index]++;
	else
		array[HISTO_BUCKETS]++;
}

static inline void spin_time_accum_spinning(u64 start)
{
	u32 delta = xen_clocksource_read() - start;

	__spin_time_accum(delta, spinlock_stats.histo_spin_spinning);
	spinlock_stats.time_spinning += delta;
}

static inline void spin_time_accum_total(u64 start)
{
	u32 delta = xen_clocksource_read() - start;

	__spin_time_accum(delta, spinlock_stats.histo_spin_total);
	spinlock_stats.time_total += delta;
}

static inline void spin_time_accum_blocked(u64 start)
{
	u32 delta = xen_clocksource_read() - start;

	__spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
	spinlock_stats.time_blocked += delta;
}
#else  /* !CONFIG_XEN_DEBUG_FS */
#define TIMEOUT			(1 << 10)
#define ADD_STATS(elem, val)	do { (void)(val); } while(0)

static inline u64 spin_time_start(void)
{
	return 0;
}

static inline void spin_time_accum_total(u64 start)
{
}
static inline void spin_time_accum_spinning(u64 start)
{
}
static inline void spin_time_accum_blocked(u64 start)
{
}
#endif  /* CONFIG_XEN_DEBUG_FS */

struct xen_spinlock {
	unsigned char lock;		/* 0 -> free; 1 -> locked */
	unsigned short spinners;	/* count of waiting cpus */
};

static int xen_spin_is_locked(struct arch_spinlock *lock)
{
	struct xen_spinlock *xl = (struct xen_spinlock *)lock;

	return xl->lock != 0;
}

static int xen_spin_is_contended(struct arch_spinlock *lock)
{
	struct xen_spinlock *xl = (struct xen_spinlock *)lock;

	/* Not strictly true; this is only the count of contended
	   lock-takers entering the slow path. */
	return xl->spinners != 0;
}

static int xen_spin_trylock(struct arch_spinlock *lock)
{
	struct xen_spinlock *xl = (struct xen_spinlock *)lock;
	u8 old = 1;

	asm("xchgb %b0,%1"
	    : "+q" (old), "+m" (xl->lock) : : "memory");

	return old == 0;
}

static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
static DEFINE_PER_CPU(struct xen_spinlock *, lock_spinners);

/*
 * Mark a cpu as interested in a lock.  Returns the CPU's previous
 * lock of interest, in case we got preempted by an interrupt.
 */
static inline struct xen_spinlock *spinning_lock(struct xen_spinlock *xl)
{
	struct xen_spinlock *prev;

	prev = __this_cpu_read(lock_spinners);
	__this_cpu_write(lock_spinners, xl);

	wmb();			/* set lock of interest before count */

	asm(LOCK_PREFIX " incw %0"
	    : "+m" (xl->spinners) : : "memory");

	return prev;
}

/*
 * Mark a cpu as no longer interested in a lock.  Restores previous
 * lock of interest (NULL for none).
 */
static inline void unspinning_lock(struct xen_spinlock *xl, struct xen_spinlock *prev)
{
	asm(LOCK_PREFIX " decw %0"
	    : "+m" (xl->spinners) : : "memory");
	wmb();			/* decrement count before restoring lock */
	__this_cpu_write(lock_spinners, prev);
}

static noinline int xen_spin_lock_slow(struct arch_spinlock *lock, bool irq_enable)
{
	struct xen_spinlock *xl = (struct xen_spinlock *)lock;
	struct xen_spinlock *prev;
	int irq = __this_cpu_read(lock_kicker_irq);
	int ret;
	u64 start;

	/* If kicker interrupts not initialized yet, just spin */
	if (irq == -1)
		return 0;

	start = spin_time_start();

	/* announce we're spinning */
	prev = spinning_lock(xl);

	ADD_STATS(taken_slow, 1);
	ADD_STATS(taken_slow_nested, prev != NULL);

	do {
		unsigned long flags;

		/* clear pending */
		xen_clear_irq_pending(irq);

		/* check again make sure it didn't become free while
		   we weren't looking  */
		ret = xen_spin_trylock(lock);
		if (ret) {
			ADD_STATS(taken_slow_pickup, 1);

			/*
			 * If we interrupted another spinlock while it
			 * was blocking, make sure it doesn't block
			 * without rechecking the lock.
			 */
			if (prev != NULL)
				xen_set_irq_pending(irq);
			goto out;
		}

		flags = arch_local_save_flags();
		if (irq_enable) {
			ADD_STATS(taken_slow_irqenable, 1);
			raw_local_irq_enable();
		}

		/*
		 * Block until irq becomes pending.  If we're
		 * interrupted at this point (after the trylock but
		 * before entering the block), then the nested lock
		 * handler guarantees that the irq will be left
		 * pending if there's any chance the lock became free;
		 * xen_poll_irq() returns immediately if the irq is
		 * pending.
		 */
		xen_poll_irq(irq);

		raw_local_irq_restore(flags);

		ADD_STATS(taken_slow_spurious, !xen_test_irq_pending(irq));
	} while (!xen_test_irq_pending(irq)); /* check for spurious wakeups */

	kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));

out:
	unspinning_lock(xl, prev);
	spin_time_accum_blocked(start);

	return ret;
}

static inline void __xen_spin_lock(struct arch_spinlock *lock, bool irq_enable)
{
	struct xen_spinlock *xl = (struct xen_spinlock *)lock;
	unsigned timeout;
	u8 oldval;
	u64 start_spin;

	ADD_STATS(taken, 1);

	start_spin = spin_time_start();

	do {
		u64 start_spin_fast = spin_time_start();

		timeout = TIMEOUT;

		asm("1: xchgb %1,%0\n"
		    "   testb %1,%1\n"
		    "   jz 3f\n"
		    "2: rep;nop\n"
		    "   cmpb $0,%0\n"
		    "   je 1b\n"
		    "   dec %2\n"
		    "   jnz 2b\n"
		    "3:\n"
		    : "+m" (xl->lock), "=q" (oldval), "+r" (timeout)
		    : "1" (1)
		    : "memory");

		spin_time_accum_spinning(start_spin_fast);

	} while (unlikely(oldval != 0 &&
			  (TIMEOUT == ~0 || !xen_spin_lock_slow(lock, irq_enable))));

	spin_time_accum_total(start_spin);
}

static void xen_spin_lock(struct arch_spinlock *lock)
{
	__xen_spin_lock(lock, false);
}

static void xen_spin_lock_flags(struct arch_spinlock *lock, unsigned long flags)
{
	__xen_spin_lock(lock, !raw_irqs_disabled_flags(flags));
}

static noinline void xen_spin_unlock_slow(struct xen_spinlock *xl)
{
	int cpu;

	ADD_STATS(released_slow, 1);

	for_each_online_cpu(cpu) {
		/* XXX should mix up next cpu selection */
		if (per_cpu(lock_spinners, cpu) == xl) {
			ADD_STATS(released_slow_kicked, 1);
			xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
			break;
		}
	}
}

static void xen_spin_unlock(struct arch_spinlock *lock)
{
	struct xen_spinlock *xl = (struct xen_spinlock *)lock;

	ADD_STATS(released, 1);

	smp_wmb();		/* make sure no writes get moved after unlock */
	xl->lock = 0;		/* release lock */

	/*
	 * Make sure unlock happens before checking for waiting
	 * spinners.  We need a strong barrier to enforce the
	 * write-read ordering to different memory locations, as the
	 * CPU makes no implied guarantees about their ordering.
	 */
	mb();

	if (unlikely(xl->spinners))
		xen_spin_unlock_slow(xl);
}

static irqreturn_t dummy_handler(int irq, void *dev_id)
{
	BUG();
	return IRQ_HANDLED;
}

void __cpuinit xen_init_lock_cpu(int cpu)
{
	int irq;
	const char *name;

	name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
	irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
				     cpu,
				     dummy_handler,
				     IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
				     name,
				     NULL);

	if (irq >= 0) {
		disable_irq(irq); /* make sure it's never delivered */
		per_cpu(lock_kicker_irq, cpu) = irq;
	}

	printk("cpu %d spinlock event irq %d\n", cpu, irq);
}

void xen_uninit_lock_cpu(int cpu)
{
	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
}

void __init xen_init_spinlocks(void)
{
	pv_lock_ops.spin_is_locked = xen_spin_is_locked;
	pv_lock_ops.spin_is_contended = xen_spin_is_contended;
	pv_lock_ops.spin_lock = xen_spin_lock;
	pv_lock_ops.spin_lock_flags = xen_spin_lock_flags;
	pv_lock_ops.spin_trylock = xen_spin_trylock;
	pv_lock_ops.spin_unlock = xen_spin_unlock;
}

#ifdef CONFIG_XEN_DEBUG_FS

static struct dentry *d_spin_debug;

static int __init xen_spinlock_debugfs(void)
{
	struct dentry *d_xen = xen_init_debugfs();

	if (d_xen == NULL)
		return -ENOMEM;

	d_spin_debug = debugfs_create_dir("spinlocks", d_xen);

	debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);

	debugfs_create_u32("timeout", 0644, d_spin_debug, &lock_timeout);

	debugfs_create_u64("taken", 0444, d_spin_debug, &spinlock_stats.taken);
	debugfs_create_u32("taken_slow", 0444, d_spin_debug,
			   &spinlock_stats.taken_slow);
	debugfs_create_u32("taken_slow_nested", 0444, d_spin_debug,
			   &spinlock_stats.taken_slow_nested);
	debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug,
			   &spinlock_stats.taken_slow_pickup);
	debugfs_create_u32("taken_slow_spurious", 0444, d_spin_debug,
			   &spinlock_stats.taken_slow_spurious);
	debugfs_create_u32("taken_slow_irqenable", 0444, d_spin_debug,
			   &spinlock_stats.taken_slow_irqenable);

	debugfs_create_u64("released", 0444, d_spin_debug, &spinlock_stats.released);
	debugfs_create_u32("released_slow", 0444, d_spin_debug,
			   &spinlock_stats.released_slow);
	debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug,
			   &spinlock_stats.released_slow_kicked);

	debugfs_create_u64("time_spinning", 0444, d_spin_debug,
			   &spinlock_stats.time_spinning);
	debugfs_create_u64("time_blocked", 0444, d_spin_debug,
			   &spinlock_stats.time_blocked);
	debugfs_create_u64("time_total", 0444, d_spin_debug,
			   &spinlock_stats.time_total);

	xen_debugfs_create_u32_array("histo_total", 0444, d_spin_debug,
				     spinlock_stats.histo_spin_total, HISTO_BUCKETS + 1);
	xen_debugfs_create_u32_array("histo_spinning", 0444, d_spin_debug,
				     spinlock_stats.histo_spin_spinning, HISTO_BUCKETS + 1);
	xen_debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
				     spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);

	return 0;
}
fs_initcall(xen_spinlock_debugfs);

#endif	/* CONFIG_XEN_DEBUG_FS */
Commit	Line	Data
d5de8841 JF	1	/*
	2	* Split spinlock implementation out into its own file, so it can be
	3	* compiled in a FTRACE-compatible way.
	4	*/
	5	#include <linux/kernel_stat.h>
	6	#include <linux/spinlock.h>
994025ca JF	7	#include <linux/debugfs.h>
994025ca JF	8	#include <linux/log2.h>
5a0e3ad6	9	#include <linux/gfp.h>
d5de8841 JF	10
	11	#include <asm/paravirt.h>
	12
	13	#include <xen/interface/xen.h>
	14	#include <xen/events.h>
	15
	16	#include "xen-ops.h"
994025ca JF	17	#include "debugfs.h"
	18
	19	#ifdef CONFIG_XEN_DEBUG_FS
	20	static struct xen_spinlock_stats
	21	{
	22	u64 taken;
	23	u32 taken_slow;
	24	u32 taken_slow_nested;
	25	u32 taken_slow_pickup;
	26	u32 taken_slow_spurious;
1e696f63	27	u32 taken_slow_irqenable;
994025ca JF	28
	29	u64 released;
	30	u32 released_slow;
	31	u32 released_slow_kicked;
	32
f8eca41f JF	33	#define HISTO_BUCKETS 30
	34	u32 histo_spin_total[HISTO_BUCKETS+1];
	35	u32 histo_spin_spinning[HISTO_BUCKETS+1];
	36	u32 histo_spin_blocked[HISTO_BUCKETS+1];
	37
	38	u64 time_total;
	39	u64 time_spinning;
	40	u64 time_blocked;
994025ca JF	41	} spinlock_stats;
	42
	43	static u8 zero_stats;
	44
	45	static unsigned lock_timeout = 1 << 10;
	46	#define TIMEOUT lock_timeout
	47
	48	static inline void check_zero(void)
	49	{
	50	if (unlikely(zero_stats)) {
	51	memset(&spinlock_stats, 0, sizeof(spinlock_stats));
	52	zero_stats = 0;
	53	}
	54	}
	55
	56	#define ADD_STATS(elem, val) \
	57	do { check_zero(); spinlock_stats.elem += (val); } while(0)
	58
	59	static inline u64 spin_time_start(void)
	60	{
	61	return xen_clocksource_read();
	62	}
	63
	64	static void __spin_time_accum(u64 delta, u32 *array)
	65	{
	66	unsigned index = ilog2(delta);
	67
	68	check_zero();
	69
	70	if (index < HISTO_BUCKETS)
	71	array[index]++;
	72	else
	73	array[HISTO_BUCKETS]++;
	74	}
	75
f8eca41f JF	76	static inline void spin_time_accum_spinning(u64 start)
	77	{
	78	u32 delta = xen_clocksource_read() - start;
	79
	80	__spin_time_accum(delta, spinlock_stats.histo_spin_spinning);
	81	spinlock_stats.time_spinning += delta;
	82	}
	83
	84	static inline void spin_time_accum_total(u64 start)
994025ca JF	85	{
	86	u32 delta = xen_clocksource_read() - start;
	87
f8eca41f JF	88	__spin_time_accum(delta, spinlock_stats.histo_spin_total);
f8eca41f JF	89	spinlock_stats.time_total += delta;
994025ca JF	90	}
994025ca JF	91
f8eca41f	92	static inline void spin_time_accum_blocked(u64 start)
994025ca JF	93	{
	94	u32 delta = xen_clocksource_read() - start;
	95
f8eca41f JF	96	__spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
f8eca41f JF	97	spinlock_stats.time_blocked += delta;
994025ca JF	98	}
	99	#else /* !CONFIG_XEN_DEBUG_FS */
	100	#define TIMEOUT (1 << 10)
	101	#define ADD_STATS(elem, val) do { (void)(val); } while(0)
	102
	103	static inline u64 spin_time_start(void)
	104	{
	105	return 0;
	106	}
	107
f8eca41f JF	108	static inline void spin_time_accum_total(u64 start)
	109	{
	110	}
	111	static inline void spin_time_accum_spinning(u64 start)
994025ca JF	112	{
994025ca JF	113	}
f8eca41f	114	static inline void spin_time_accum_blocked(u64 start)
994025ca JF	115	{
	116	}
	117	#endif /* CONFIG_XEN_DEBUG_FS */
d5de8841 JF	118
	119	struct xen_spinlock {
	120	unsigned char lock; /* 0 -> free; 1 -> locked */
	121	unsigned short spinners; /* count of waiting cpus */
	122	};
	123
445c8951	124	static int xen_spin_is_locked(struct arch_spinlock *lock)
d5de8841 JF	125	{
	126	struct xen_spinlock xl = (struct xen_spinlock )lock;
	127
	128	return xl->lock != 0;
	129	}
	130
445c8951	131	static int xen_spin_is_contended(struct arch_spinlock *lock)
d5de8841 JF	132	{
	133	struct xen_spinlock xl = (struct xen_spinlock )lock;
	134
	135	/* Not strictly true; this is only the count of contended
	136	lock-takers entering the slow path. */
	137	return xl->spinners != 0;
	138	}
	139
445c8951	140	static int xen_spin_trylock(struct arch_spinlock *lock)
d5de8841 JF	141	{
	142	struct xen_spinlock xl = (struct xen_spinlock )lock;
	143	u8 old = 1;
	144
	145	asm("xchgb %b0,%1"
	146	: "+q" (old), "+m" (xl->lock) : : "memory");
	147
	148	return old == 0;
	149	}
	150
	151	static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
	152	static DEFINE_PER_CPU(struct xen_spinlock *, lock_spinners);
	153
168d2f46 JF	154	/*
	155	* Mark a cpu as interested in a lock. Returns the CPU's previous
	156	* lock of interest, in case we got preempted by an interrupt.
	157	*/
	158	static inline struct xen_spinlock spinning_lock(struct xen_spinlock xl)
d5de8841	159	{
168d2f46 JF	160	struct xen_spinlock *prev;
168d2f46 JF	161
780f36d8 CL	162	prev = __this_cpu_read(lock_spinners);
780f36d8 CL	163	__this_cpu_write(lock_spinners, xl);
168d2f46	164
d5de8841	165	wmb(); /* set lock of interest before count */
168d2f46	166
d5de8841 JF	167	asm(LOCK_PREFIX " incw %0"
d5de8841 JF	168	: "+m" (xl->spinners) : : "memory");
168d2f46 JF	169
168d2f46 JF	170	return prev;
d5de8841 JF	171	}
d5de8841 JF	172
168d2f46 JF	173	/*
	174	* Mark a cpu as no longer interested in a lock. Restores previous
	175	* lock of interest (NULL for none).
	176	*/
	177	static inline void unspinning_lock(struct xen_spinlock xl, struct xen_spinlock prev)
d5de8841 JF	178	{
	179	asm(LOCK_PREFIX " decw %0"
	180	: "+m" (xl->spinners) : : "memory");
168d2f46	181	wmb(); /* decrement count before restoring lock */
780f36d8	182	__this_cpu_write(lock_spinners, prev);
d5de8841 JF	183	}
d5de8841 JF	184
445c8951	185	static noinline int xen_spin_lock_slow(struct arch_spinlock *lock, bool irq_enable)
d5de8841 JF	186	{
d5de8841 JF	187	struct xen_spinlock xl = (struct xen_spinlock )lock;
168d2f46	188	struct xen_spinlock *prev;
780f36d8	189	int irq = __this_cpu_read(lock_kicker_irq);
d5de8841	190	int ret;
f8eca41f	191	u64 start;
d5de8841 JF	192
	193	/* If kicker interrupts not initialized yet, just spin */
	194	if (irq == -1)
	195	return 0;
	196
f8eca41f JF	197	start = spin_time_start();
f8eca41f JF	198
d5de8841	199	/* announce we're spinning */
168d2f46	200	prev = spinning_lock(xl);
d5de8841	201
994025ca JF	202	ADD_STATS(taken_slow, 1);
	203	ADD_STATS(taken_slow_nested, prev != NULL);
	204
168d2f46	205	do {
4d576b57 JF	206	unsigned long flags;
4d576b57 JF	207
168d2f46 JF	208	/* clear pending */
	209	xen_clear_irq_pending(irq);
	210
	211	/* check again make sure it didn't become free while
	212	we weren't looking */
	213	ret = xen_spin_trylock(lock);
	214	if (ret) {
994025ca JF	215	ADD_STATS(taken_slow_pickup, 1);
994025ca JF	216
168d2f46 JF	217	/*
	218	* If we interrupted another spinlock while it
	219	* was blocking, make sure it doesn't block
	220	* without rechecking the lock.
	221	*/
	222	if (prev != NULL)
	223	xen_set_irq_pending(irq);
	224	goto out;
	225	}
d5de8841	226
df9ee292	227	flags = arch_local_save_flags();
4d576b57 JF	228	if (irq_enable) {
	229	ADD_STATS(taken_slow_irqenable, 1);
	230	raw_local_irq_enable();
	231	}
	232
168d2f46 JF	233	/*
	234	* Block until irq becomes pending. If we're
	235	* interrupted at this point (after the trylock but
	236	* before entering the block), then the nested lock
	237	* handler guarantees that the irq will be left
	238	* pending if there's any chance the lock became free;
	239	* xen_poll_irq() returns immediately if the irq is
	240	* pending.
	241	*/
	242	xen_poll_irq(irq);
4d576b57 JF	243
	244	raw_local_irq_restore(flags);
	245
994025ca	246	ADD_STATS(taken_slow_spurious, !xen_test_irq_pending(irq));
168d2f46	247	} while (!xen_test_irq_pending(irq)); /* check for spurious wakeups */
d5de8841	248
d6c88a50	249	kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));
d5de8841 JF	250
d5de8841 JF	251	out:
168d2f46	252	unspinning_lock(xl, prev);
f8eca41f JF	253	spin_time_accum_blocked(start);
f8eca41f JF	254
d5de8841 JF	255	return ret;
	256	}
	257
445c8951	258	static inline void __xen_spin_lock(struct arch_spinlock *lock, bool irq_enable)
d5de8841 JF	259	{
d5de8841 JF	260	struct xen_spinlock xl = (struct xen_spinlock )lock;
994025ca	261	unsigned timeout;
d5de8841	262	u8 oldval;
994025ca JF	263	u64 start_spin;
	264
	265	ADD_STATS(taken, 1);
	266
	267	start_spin = spin_time_start();
d5de8841 JF	268
d5de8841 JF	269	do {
994025ca JF	270	u64 start_spin_fast = spin_time_start();
	271
	272	timeout = TIMEOUT;
d5de8841 JF	273
	274	asm("1: xchgb %1,%0\n"
	275	" testb %1,%1\n"
	276	" jz 3f\n"
	277	"2: rep;nop\n"
	278	" cmpb $0,%0\n"
	279	" je 1b\n"
	280	" dec %2\n"
	281	" jnz 2b\n"
	282	"3:\n"
	283	: "+m" (xl->lock), "=q" (oldval), "+r" (timeout)
	284	: "1" (1)
	285	: "memory");
	286
f8eca41f	287	spin_time_accum_spinning(start_spin_fast);
1e696f63 JF	288
	289	} while (unlikely(oldval != 0 &&
	290	(TIMEOUT == ~0 \|\| !xen_spin_lock_slow(lock, irq_enable))));
994025ca	291
f8eca41f	292	spin_time_accum_total(start_spin);
d5de8841 JF	293	}
d5de8841 JF	294
445c8951	295	static void xen_spin_lock(struct arch_spinlock *lock)
1e696f63 JF	296	{
	297	__xen_spin_lock(lock, false);
	298	}
	299
445c8951	300	static void xen_spin_lock_flags(struct arch_spinlock *lock, unsigned long flags)
1e696f63 JF	301	{
	302	__xen_spin_lock(lock, !raw_irqs_disabled_flags(flags));
	303	}
	304
d5de8841 JF	305	static noinline void xen_spin_unlock_slow(struct xen_spinlock *xl)
	306	{
	307	int cpu;
	308
994025ca JF	309	ADD_STATS(released_slow, 1);
994025ca JF	310
d5de8841 JF	311	for_each_online_cpu(cpu) {
	312	/* XXX should mix up next cpu selection */
	313	if (per_cpu(lock_spinners, cpu) == xl) {
994025ca	314	ADD_STATS(released_slow_kicked, 1);
d5de8841 JF	315	xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
	316	break;
	317	}
	318	}
	319	}
	320
445c8951	321	static void xen_spin_unlock(struct arch_spinlock *lock)
d5de8841 JF	322	{
	323	struct xen_spinlock xl = (struct xen_spinlock )lock;
	324
994025ca JF	325	ADD_STATS(released, 1);
994025ca JF	326
d5de8841 JF	327	smp_wmb(); /* make sure no writes get moved after unlock */
	328	xl->lock = 0; /* release lock */
	329
2496afbf YX	330	/*
	331	* Make sure unlock happens before checking for waiting
	332	* spinners. We need a strong barrier to enforce the
	333	* write-read ordering to different memory locations, as the
	334	* CPU makes no implied guarantees about their ordering.
	335	*/
	336	mb();
d5de8841 JF	337
	338	if (unlikely(xl->spinners))
	339	xen_spin_unlock_slow(xl);
	340	}
	341
	342	static irqreturn_t dummy_handler(int irq, void *dev_id)
	343	{
	344	BUG();
	345	return IRQ_HANDLED;
	346	}
	347
	348	void __cpuinit xen_init_lock_cpu(int cpu)
	349	{
	350	int irq;
	351	const char *name;
	352
	353	name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
	354	irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
	355	cpu,
	356	dummy_handler,
	357	IRQF_DISABLED\|IRQF_PERCPU\|IRQF_NOBALANCING,
	358	name,
	359	NULL);
	360
	361	if (irq >= 0) {
	362	disable_irq(irq); /* make sure it's never delivered */
	363	per_cpu(lock_kicker_irq, cpu) = irq;
	364	}
	365
	366	printk("cpu %d spinlock event irq %d\n", cpu, irq);
	367	}
	368
d68d82af AN	369	void xen_uninit_lock_cpu(int cpu)
	370	{
	371	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
	372	}
	373
d5de8841 JF	374	void __init xen_init_spinlocks(void)
	375	{
	376	pv_lock_ops.spin_is_locked = xen_spin_is_locked;
	377	pv_lock_ops.spin_is_contended = xen_spin_is_contended;
	378	pv_lock_ops.spin_lock = xen_spin_lock;
1e696f63	379	pv_lock_ops.spin_lock_flags = xen_spin_lock_flags;
d5de8841 JF	380	pv_lock_ops.spin_trylock = xen_spin_trylock;
	381	pv_lock_ops.spin_unlock = xen_spin_unlock;
	382	}
994025ca JF	383
	384	#ifdef CONFIG_XEN_DEBUG_FS
	385
	386	static struct dentry *d_spin_debug;
	387
	388	static int __init xen_spinlock_debugfs(void)
	389	{
	390	struct dentry *d_xen = xen_init_debugfs();
	391
	392	if (d_xen == NULL)
	393	return -ENOMEM;
	394
	395	d_spin_debug = debugfs_create_dir("spinlocks", d_xen);
	396
	397	debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats);
	398
	399	debugfs_create_u32("timeout", 0644, d_spin_debug, &lock_timeout);
	400
	401	debugfs_create_u64("taken", 0444, d_spin_debug, &spinlock_stats.taken);
	402	debugfs_create_u32("taken_slow", 0444, d_spin_debug,
	403	&spinlock_stats.taken_slow);
	404	debugfs_create_u32("taken_slow_nested", 0444, d_spin_debug,
	405	&spinlock_stats.taken_slow_nested);
	406	debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug,
	407	&spinlock_stats.taken_slow_pickup);
	408	debugfs_create_u32("taken_slow_spurious", 0444, d_spin_debug,
	409	&spinlock_stats.taken_slow_spurious);
1e696f63 JF	410	debugfs_create_u32("taken_slow_irqenable", 0444, d_spin_debug,
1e696f63 JF	411	&spinlock_stats.taken_slow_irqenable);
994025ca JF	412
	413	debugfs_create_u64("released", 0444, d_spin_debug, &spinlock_stats.released);
	414	debugfs_create_u32("released_slow", 0444, d_spin_debug,
	415	&spinlock_stats.released_slow);
	416	debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug,
	417	&spinlock_stats.released_slow_kicked);
	418
	419	debugfs_create_u64("time_spinning", 0444, d_spin_debug,
f8eca41f JF	420	&spinlock_stats.time_spinning);
	421	debugfs_create_u64("time_blocked", 0444, d_spin_debug,
	422	&spinlock_stats.time_blocked);
994025ca	423	debugfs_create_u64("time_total", 0444, d_spin_debug,
f8eca41f	424	&spinlock_stats.time_total);
994025ca JF	425
994025ca JF	426	xen_debugfs_create_u32_array("histo_total", 0444, d_spin_debug,
f8eca41f	427	spinlock_stats.histo_spin_total, HISTO_BUCKETS + 1);
994025ca	428	xen_debugfs_create_u32_array("histo_spinning", 0444, d_spin_debug,
f8eca41f JF	429	spinlock_stats.histo_spin_spinning, HISTO_BUCKETS + 1);
	430	xen_debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
	431	spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);
994025ca JF	432
	433	return 0;
	434	}
	435	fs_initcall(xen_spinlock_debugfs);
	436
	437	#endif /* CONFIG_XEN_DEBUG_FS */