Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1007 insertions, 0 deletions

diff --git a/arch/powerpc/lib/qspinlock.c b/arch/powerpc/lib/qspinlock.c
new file mode 100644
index 0000000000..6dd2f46bd3
--- /dev/null
+++ b/arch/powerpc/lib/qspinlock.c
@@ -0,0 +1,1007 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/bug.h>
+#include <linux/compiler.h>
+#include <linux/export.h>
+#include <linux/percpu.h>
+#include <linux/processor.h>
+#include <linux/smp.h>
+#include <linux/topology.h>
+#include <linux/sched/clock.h>
+#include <asm/qspinlock.h>
+#include <asm/paravirt.h>
+
+#define MAX_NODES	4
+
+struct qnode {
+	struct qnode	*next;
+	struct qspinlock *lock;
+	int		cpu;
+	int		yield_cpu;
+	u8		locked; /* 1 if lock acquired */
+};
+
+struct qnodes {
+	int		count;
+	struct qnode nodes[MAX_NODES];
+};
+
+/* Tuning parameters */
+static int steal_spins __read_mostly = (1 << 5);
+static int remote_steal_spins __read_mostly = (1 << 2);
+#if _Q_SPIN_TRY_LOCK_STEAL == 1
+static const bool maybe_stealers = true;
+#else
+static bool maybe_stealers __read_mostly = true;
+#endif
+static int head_spins __read_mostly = (1 << 8);
+
+static bool pv_yield_owner __read_mostly = true;
+static bool pv_yield_allow_steal __read_mostly = false;
+static bool pv_spin_on_preempted_owner __read_mostly = false;
+static bool pv_sleepy_lock __read_mostly = true;
+static bool pv_sleepy_lock_sticky __read_mostly = false;
+static u64 pv_sleepy_lock_interval_ns __read_mostly = 0;
+static int pv_sleepy_lock_factor __read_mostly = 256;
+static bool pv_yield_prev __read_mostly = true;
+static bool pv_yield_propagate_owner __read_mostly = true;
+static bool pv_prod_head __read_mostly = false;
+
+static DEFINE_PER_CPU_ALIGNED(struct qnodes, qnodes);
+static DEFINE_PER_CPU_ALIGNED(u64, sleepy_lock_seen_clock);
+
+#if _Q_SPIN_SPEC_BARRIER == 1
+#define spec_barrier() do { asm volatile("ori 31,31,0" ::: "memory"); } while (0)
+#else
+#define spec_barrier() do { } while (0)
+#endif
+
+static __always_inline bool recently_sleepy(void)
+{
+	/* pv_sleepy_lock is true when this is called */
+	if (pv_sleepy_lock_interval_ns) {
+		u64 seen = this_cpu_read(sleepy_lock_seen_clock);
+
+		if (seen) {
+			u64 delta = sched_clock() - seen;
+			if (delta < pv_sleepy_lock_interval_ns)
+				return true;
+			this_cpu_write(sleepy_lock_seen_clock, 0);
+		}
+	}
+
+	return false;
+}
+
+static __always_inline int get_steal_spins(bool paravirt, bool sleepy)
+{
+	if (paravirt && sleepy)
+		return steal_spins * pv_sleepy_lock_factor;
+	else
+		return steal_spins;
+}
+
+static __always_inline int get_remote_steal_spins(bool paravirt, bool sleepy)
+{
+	if (paravirt && sleepy)
+		return remote_steal_spins * pv_sleepy_lock_factor;
+	else
+		return remote_steal_spins;
+}
+
+static __always_inline int get_head_spins(bool paravirt, bool sleepy)
+{
+	if (paravirt && sleepy)
+		return head_spins * pv_sleepy_lock_factor;
+	else
+		return head_spins;
+}
+
+static inline u32 encode_tail_cpu(int cpu)
+{
+	return (cpu + 1) << _Q_TAIL_CPU_OFFSET;
+}
+
+static inline int decode_tail_cpu(u32 val)
+{
+	return (val >> _Q_TAIL_CPU_OFFSET) - 1;
+}
+
+static inline int get_owner_cpu(u32 val)
+{
+	return (val & _Q_OWNER_CPU_MASK) >> _Q_OWNER_CPU_OFFSET;
+}
+
+/*
+ * Try to acquire the lock if it was not already locked. If the tail matches
+ * mytail then clear it, otherwise leave it unchnaged. Return previous value.
+ *
+ * This is used by the head of the queue to acquire the lock and clean up
+ * its tail if it was the last one queued.
+ */
+static __always_inline u32 trylock_clean_tail(struct qspinlock *lock, u32 tail)
+{
+	u32 newval = queued_spin_encode_locked_val();
+	u32 prev, tmp;
+
+	asm volatile(
+"1:	lwarx	%0,0,%2,%7	# trylock_clean_tail			\n"
+	/* This test is necessary if there could be stealers */
+"	andi.	%1,%0,%5						\n"
+"	bne	3f							\n"
+	/* Test whether the lock tail == mytail */
+"	and	%1,%0,%6						\n"
+"	cmpw	0,%1,%3							\n"
+	/* Merge the new locked value */
+"	or	%1,%1,%4						\n"
+"	bne	2f							\n"
+	/* If the lock tail matched, then clear it, otherwise leave it. */
+"	andc	%1,%1,%6						\n"
+"2:	stwcx.	%1,0,%2							\n"
+"	bne-	1b							\n"
+"\t"	PPC_ACQUIRE_BARRIER "						\n"
+"3:									\n"
+	: "=&r" (prev), "=&r" (tmp)
+	: "r" (&lock->val), "r"(tail), "r" (newval),
+	  "i" (_Q_LOCKED_VAL),
+	  "r" (_Q_TAIL_CPU_MASK),
+	  "i" (_Q_SPIN_EH_HINT)
+	: "cr0", "memory");
+
+	return prev;
+}
+
+/*
+ * Publish our tail, replacing previous tail. Return previous value.
+ *
+ * This provides a release barrier for publishing node, this pairs with the
+ * acquire barrier in get_tail_qnode() when the next CPU finds this tail
+ * value.
+ */
+static __always_inline u32 publish_tail_cpu(struct qspinlock *lock, u32 tail)
+{
+	u32 prev, tmp;
+
+	kcsan_release();
+
+	asm volatile(
+"\t"	PPC_RELEASE_BARRIER "						\n"
+"1:	lwarx	%0,0,%2		# publish_tail_cpu			\n"
+"	andc	%1,%0,%4						\n"
+"	or	%1,%1,%3						\n"
+"	stwcx.	%1,0,%2							\n"
+"	bne-	1b							\n"
+	: "=&r" (prev), "=&r"(tmp)
+	: "r" (&lock->val), "r" (tail), "r"(_Q_TAIL_CPU_MASK)
+	: "cr0", "memory");
+
+	return prev;
+}
+
+static __always_inline u32 set_mustq(struct qspinlock *lock)
+{
+	u32 prev;
+
+	asm volatile(
+"1:	lwarx	%0,0,%1		# set_mustq				\n"
+"	or	%0,%0,%2						\n"
+"	stwcx.	%0,0,%1							\n"
+"	bne-	1b							\n"
+	: "=&r" (prev)
+	: "r" (&lock->val), "r" (_Q_MUST_Q_VAL)
+	: "cr0", "memory");
+
+	return prev;
+}
+
+static __always_inline u32 clear_mustq(struct qspinlock *lock)
+{
+	u32 prev;
+
+	asm volatile(
+"1:	lwarx	%0,0,%1		# clear_mustq				\n"
+"	andc	%0,%0,%2						\n"
+"	stwcx.	%0,0,%1							\n"
+"	bne-	1b							\n"
+	: "=&r" (prev)
+	: "r" (&lock->val), "r" (_Q_MUST_Q_VAL)
+	: "cr0", "memory");
+
+	return prev;
+}
+
+static __always_inline bool try_set_sleepy(struct qspinlock *lock, u32 old)
+{
+	u32 prev;
+	u32 new = old | _Q_SLEEPY_VAL;
+
+	BUG_ON(!(old & _Q_LOCKED_VAL));
+	BUG_ON(old & _Q_SLEEPY_VAL);
+
+	asm volatile(
+"1:	lwarx	%0,0,%1		# try_set_sleepy			\n"
+"	cmpw	0,%0,%2							\n"
+"	bne-	2f							\n"
+"	stwcx.	%3,0,%1							\n"
+"	bne-	1b							\n"
+"2:									\n"
+	: "=&r" (prev)
+	: "r" (&lock->val), "r"(old), "r" (new)
+	: "cr0", "memory");
+
+	return likely(prev == old);
+}
+
+static __always_inline void seen_sleepy_owner(struct qspinlock *lock, u32 val)
+{
+	if (pv_sleepy_lock) {
+		if (pv_sleepy_lock_interval_ns)
+			this_cpu_write(sleepy_lock_seen_clock, sched_clock());
+		if (!(val & _Q_SLEEPY_VAL))
+			try_set_sleepy(lock, val);
+	}
+}
+
+static __always_inline void seen_sleepy_lock(void)
+{
+	if (pv_sleepy_lock && pv_sleepy_lock_interval_ns)
+		this_cpu_write(sleepy_lock_seen_clock, sched_clock());
+}
+
+static __always_inline void seen_sleepy_node(struct qspinlock *lock, u32 val)
+{
+	if (pv_sleepy_lock) {
+		if (pv_sleepy_lock_interval_ns)
+			this_cpu_write(sleepy_lock_seen_clock, sched_clock());
+		if (val & _Q_LOCKED_VAL) {
+			if (!(val & _Q_SLEEPY_VAL))
+				try_set_sleepy(lock, val);
+		}
+	}
+}
+
+static struct qnode *get_tail_qnode(struct qspinlock *lock, u32 val)
+{
+	int cpu = decode_tail_cpu(val);
+	struct qnodes *qnodesp = per_cpu_ptr(&qnodes, cpu);
+	int idx;
+
+	/*
+	 * After publishing the new tail and finding a previous tail in the
+	 * previous val (which is the control dependency), this barrier
+	 * orders the release barrier in publish_tail_cpu performed by the
+	 * last CPU, with subsequently looking at its qnode structures
+	 * after the barrier.
+	 */
+	smp_acquire__after_ctrl_dep();
+
+	for (idx = 0; idx < MAX_NODES; idx++) {
+		struct qnode *qnode = &qnodesp->nodes[idx];
+		if (qnode->lock == lock)
+			return qnode;
+	}
+
+	BUG();
+}
+
+/* Called inside spin_begin(). Returns whether or not the vCPU was preempted. */
+static __always_inline bool __yield_to_locked_owner(struct qspinlock *lock, u32 val, bool paravirt, bool mustq)
+{
+	int owner;
+	u32 yield_count;
+	bool preempted = false;
+
+	BUG_ON(!(val & _Q_LOCKED_VAL));
+
+	if (!paravirt)
+		goto relax;
+
+	if (!pv_yield_owner)
+		goto relax;
+
+	owner = get_owner_cpu(val);
+	yield_count = yield_count_of(owner);
+
+	if ((yield_count & 1) == 0)
+		goto relax; /* owner vcpu is running */
+
+	spin_end();
+
+	seen_sleepy_owner(lock, val);
+	preempted = true;
+
+	/*
+	 * Read the lock word after sampling the yield count. On the other side
+	 * there may a wmb because the yield count update is done by the
+	 * hypervisor preemption and the value update by the OS, however this
+	 * ordering might reduce the chance of out of order accesses and
+	 * improve the heuristic.
+	 */
+	smp_rmb();
+
+	if (READ_ONCE(lock->val) == val) {
+		if (mustq)
+			clear_mustq(lock);
+		yield_to_preempted(owner, yield_count);
+		if (mustq)
+			set_mustq(lock);
+		spin_begin();
+
+		/* Don't relax if we yielded. Maybe we should? */
+		return preempted;
+	}
+	spin_begin();
+relax:
+	spin_cpu_relax();
+
+	return preempted;
+}
+
+/* Called inside spin_begin(). Returns whether or not the vCPU was preempted. */
+static __always_inline bool yield_to_locked_owner(struct qspinlock *lock, u32 val, bool paravirt)
+{
+	return __yield_to_locked_owner(lock, val, paravirt, false);
+}
+
+/* Called inside spin_begin(). Returns whether or not the vCPU was preempted. */
+static __always_inline bool yield_head_to_locked_owner(struct qspinlock *lock, u32 val, bool paravirt)
+{
+	bool mustq = false;
+
+	if ((val & _Q_MUST_Q_VAL) && pv_yield_allow_steal)
+		mustq = true;
+
+	return __yield_to_locked_owner(lock, val, paravirt, mustq);
+}
+
+static __always_inline void propagate_yield_cpu(struct qnode *node, u32 val, int *set_yield_cpu, bool paravirt)
+{
+	struct qnode *next;
+	int owner;
+
+	if (!paravirt)
+		return;
+	if (!pv_yield_propagate_owner)
+		return;
+
+	owner = get_owner_cpu(val);
+	if (*set_yield_cpu == owner)
+		return;
+
+	next = READ_ONCE(node->next);
+	if (!next)
+		return;
+
+	if (vcpu_is_preempted(owner)) {
+		next->yield_cpu = owner;
+		*set_yield_cpu = owner;
+	} else if (*set_yield_cpu != -1) {
+		next->yield_cpu = owner;
+		*set_yield_cpu = owner;
+	}
+}
+
+/* Called inside spin_begin() */
+static __always_inline bool yield_to_prev(struct qspinlock *lock, struct qnode *node, u32 val, bool paravirt)
+{
+	int prev_cpu = decode_tail_cpu(val);
+	u32 yield_count;
+	int yield_cpu;
+	bool preempted = false;
+
+	if (!paravirt)
+		goto relax;
+
+	if (!pv_yield_propagate_owner)
+		goto yield_prev;
+
+	yield_cpu = READ_ONCE(node->yield_cpu);
+	if (yield_cpu == -1) {
+		/* Propagate back the -1 CPU */
+		if (node->next && node->next->yield_cpu != -1)
+			node->next->yield_cpu = yield_cpu;
+		goto yield_prev;
+	}
+
+	yield_count = yield_count_of(yield_cpu);
+	if ((yield_count & 1) == 0)
+		goto yield_prev; /* owner vcpu is running */
+
+	if (get_owner_cpu(READ_ONCE(lock->val)) != yield_cpu)
+		goto yield_prev; /* re-sample lock owner */
+
+	spin_end();
+
+	preempted = true;
+	seen_sleepy_node(lock, val);
+
+	smp_rmb();
+
+	if (yield_cpu == node->yield_cpu) {
+		if (node->next && node->next->yield_cpu != yield_cpu)
+			node->next->yield_cpu = yield_cpu;
+		yield_to_preempted(yield_cpu, yield_count);
+		spin_begin();
+		return preempted;
+	}
+	spin_begin();
+
+yield_prev:
+	if (!pv_yield_prev)
+		goto relax;
+
+	yield_count = yield_count_of(prev_cpu);
+	if ((yield_count & 1) == 0)
+		goto relax; /* owner vcpu is running */
+
+	spin_end();
+
+	preempted = true;
+	seen_sleepy_node(lock, val);
+
+	smp_rmb(); /* See __yield_to_locked_owner comment */
+
+	if (!READ_ONCE(node->locked)) {
+		yield_to_preempted(prev_cpu, yield_count);
+		spin_begin();
+		return preempted;
+	}
+	spin_begin();
+
+relax:
+	spin_cpu_relax();
+
+	return preempted;
+}
+
+static __always_inline bool steal_break(u32 val, int iters, bool paravirt, bool sleepy)
+{
+	if (iters >= get_steal_spins(paravirt, sleepy))
+		return true;
+
+	if (IS_ENABLED(CONFIG_NUMA) &&
+	    (iters >= get_remote_steal_spins(paravirt, sleepy))) {
+		int cpu = get_owner_cpu(val);
+		if (numa_node_id() != cpu_to_node(cpu))
+			return true;
+	}
+	return false;
+}
+
+static __always_inline bool try_to_steal_lock(struct qspinlock *lock, bool paravirt)
+{
+	bool seen_preempted = false;
+	bool sleepy = false;
+	int iters = 0;
+	u32 val;
+
+	if (!steal_spins) {
+		/* XXX: should spin_on_preempted_owner do anything here? */
+		return false;
+	}
+
+	/* Attempt to steal the lock */
+	spin_begin();
+	do {
+		bool preempted = false;
+
+		val = READ_ONCE(lock->val);
+		if (val & _Q_MUST_Q_VAL)
+			break;
+		spec_barrier();
+
+		if (unlikely(!(val & _Q_LOCKED_VAL))) {
+			spin_end();
+			if (__queued_spin_trylock_steal(lock))
+				return true;
+			spin_begin();
+		} else {
+			preempted = yield_to_locked_owner(lock, val, paravirt);
+		}
+
+		if (paravirt && pv_sleepy_lock) {
+			if (!sleepy) {
+				if (val & _Q_SLEEPY_VAL) {
+					seen_sleepy_lock();
+					sleepy = true;
+				} else if (recently_sleepy()) {
+					sleepy = true;
+				}
+			}
+			if (pv_sleepy_lock_sticky && seen_preempted &&
+			    !(val & _Q_SLEEPY_VAL)) {
+				if (try_set_sleepy(lock, val))
+					val |= _Q_SLEEPY_VAL;
+			}
+		}
+
+		if (preempted) {
+			seen_preempted = true;
+			sleepy = true;
+			if (!pv_spin_on_preempted_owner)
+				iters++;
+			/*
+			 * pv_spin_on_preempted_owner don't increase iters
+			 * while the owner is preempted -- we won't interfere
+			 * with it by definition. This could introduce some
+			 * latency issue if we continually observe preempted
+			 * owners, but hopefully that's a rare corner case of
+			 * a badly oversubscribed system.
+			 */
+		} else {
+			iters++;
+		}
+	} while (!steal_break(val, iters, paravirt, sleepy));
+
+	spin_end();
+
+	return false;
+}
+
+static __always_inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, bool paravirt)
+{
+	struct qnodes *qnodesp;
+	struct qnode *next, *node;
+	u32 val, old, tail;
+	bool seen_preempted = false;
+	bool sleepy = false;
+	bool mustq = false;
+	int idx;
+	int set_yield_cpu = -1;
+	int iters = 0;
+
+	BUILD_BUG_ON(CONFIG_NR_CPUS >= (1U << _Q_TAIL_CPU_BITS));
+
+	qnodesp = this_cpu_ptr(&qnodes);
+	if (unlikely(qnodesp->count >= MAX_NODES)) {
+		spec_barrier();
+		while (!queued_spin_trylock(lock))
+			cpu_relax();
+		return;
+	}
+
+	idx = qnodesp->count++;
+	/*
+	 * Ensure that we increment the head node->count before initialising
+	 * the actual node. If the compiler is kind enough to reorder these
+	 * stores, then an IRQ could overwrite our assignments.
+	 */
+	barrier();
+	node = &qnodesp->nodes[idx];
+	node->next = NULL;
+	node->lock = lock;
+	node->cpu = smp_processor_id();
+	node->yield_cpu = -1;
+	node->locked = 0;
+
+	tail = encode_tail_cpu(node->cpu);
+
+	/*
+	 * Assign all attributes of a node before it can be published.
+	 * Issues an lwsync, serving as a release barrier, as well as a
+	 * compiler barrier.
+	 */
+	old = publish_tail_cpu(lock, tail);
+
+	/*
+	 * If there was a previous node; link it and wait until reaching the
+	 * head of the waitqueue.
+	 */
+	if (old & _Q_TAIL_CPU_MASK) {
+		struct qnode *prev = get_tail_qnode(lock, old);
+
+		/* Link @node into the waitqueue. */
+		WRITE_ONCE(prev->next, node);
+
+		/* Wait for mcs node lock to be released */
+		spin_begin();
+		while (!READ_ONCE(node->locked)) {
+			spec_barrier();
+
+			if (yield_to_prev(lock, node, old, paravirt))
+				seen_preempted = true;
+		}
+		spec_barrier();
+		spin_end();
+
+		/* Clear out stale propagated yield_cpu */
+		if (paravirt && pv_yield_propagate_owner && node->yield_cpu != -1)
+			node->yield_cpu = -1;
+
+		smp_rmb(); /* acquire barrier for the mcs lock */
+
+		/*
+		 * Generic qspinlocks have this prefetch here, but it seems
+		 * like it could cause additional line transitions because
+		 * the waiter will keep loading from it.
+		 */
+		if (_Q_SPIN_PREFETCH_NEXT) {
+			next = READ_ONCE(node->next);
+			if (next)
+				prefetchw(next);
+		}
+	}
+
+	/* We're at the head of the waitqueue, wait for the lock. */
+again:
+	spin_begin();
+	for (;;) {
+		bool preempted;
+
+		val = READ_ONCE(lock->val);
+		if (!(val & _Q_LOCKED_VAL))
+			break;
+		spec_barrier();
+
+		if (paravirt && pv_sleepy_lock && maybe_stealers) {
+			if (!sleepy) {
+				if (val & _Q_SLEEPY_VAL) {
+					seen_sleepy_lock();
+					sleepy = true;
+				} else if (recently_sleepy()) {
+					sleepy = true;
+				}
+			}
+			if (pv_sleepy_lock_sticky && seen_preempted &&
+			    !(val & _Q_SLEEPY_VAL)) {
+				if (try_set_sleepy(lock, val))
+					val |= _Q_SLEEPY_VAL;
+			}
+		}
+
+		propagate_yield_cpu(node, val, &set_yield_cpu, paravirt);
+		preempted = yield_head_to_locked_owner(lock, val, paravirt);
+		if (!maybe_stealers)
+			continue;
+
+		if (preempted)
+			seen_preempted = true;
+
+		if (paravirt && preempted) {
+			sleepy = true;
+
+			if (!pv_spin_on_preempted_owner)
+				iters++;
+		} else {
+			iters++;
+		}
+
+		if (!mustq && iters >= get_head_spins(paravirt, sleepy)) {
+			mustq = true;
+			set_mustq(lock);
+			val |= _Q_MUST_Q_VAL;
+		}
+	}
+	spec_barrier();
+	spin_end();
+
+	/* If we're the last queued, must clean up the tail. */
+	old = trylock_clean_tail(lock, tail);
+	if (unlikely(old & _Q_LOCKED_VAL)) {
+		BUG_ON(!maybe_stealers);
+		goto again; /* Can only be true if maybe_stealers. */
+	}
+
+	if ((old & _Q_TAIL_CPU_MASK) == tail)
+		goto release; /* We were the tail, no next. */
+
+	/* There is a next, must wait for node->next != NULL (MCS protocol) */
+	next = READ_ONCE(node->next);
+	if (!next) {
+		spin_begin();
+		while (!(next = READ_ONCE(node->next)))
+			cpu_relax();
+		spin_end();
+	}
+	spec_barrier();
+
+	/*
+	 * Unlock the next mcs waiter node. Release barrier is not required
+	 * here because the acquirer is only accessing the lock word, and
+	 * the acquire barrier we took the lock with orders that update vs
+	 * this store to locked. The corresponding barrier is the smp_rmb()
+	 * acquire barrier for mcs lock, above.
+	 */
+	if (paravirt && pv_prod_head) {
+		int next_cpu = next->cpu;
+		WRITE_ONCE(next->locked, 1);
+		if (_Q_SPIN_MISO)
+			asm volatile("miso" ::: "memory");
+		if (vcpu_is_preempted(next_cpu))
+			prod_cpu(next_cpu);
+	} else {
+		WRITE_ONCE(next->locked, 1);
+		if (_Q_SPIN_MISO)
+			asm volatile("miso" ::: "memory");
+	}
+
+release:
+	qnodesp->count--; /* release the node */
+}
+
+void queued_spin_lock_slowpath(struct qspinlock *lock)
+{
+	/*
+	 * This looks funny, but it induces the compiler to inline both
+	 * sides of the branch rather than share code as when the condition
+	 * is passed as the paravirt argument to the functions.
+	 */
+	if (IS_ENABLED(CONFIG_PARAVIRT_SPINLOCKS) && is_shared_processor()) {
+		if (try_to_steal_lock(lock, true)) {
+			spec_barrier();
+			return;
+		}
+		queued_spin_lock_mcs_queue(lock, true);
+	} else {
+		if (try_to_steal_lock(lock, false)) {
+			spec_barrier();
+			return;
+		}
+		queued_spin_lock_mcs_queue(lock, false);
+	}
+}
+EXPORT_SYMBOL(queued_spin_lock_slowpath);
+
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+void pv_spinlocks_init(void)
+{
+}
+#endif
+
+#include <linux/debugfs.h>
+static int steal_spins_set(void *data, u64 val)
+{
+#if _Q_SPIN_TRY_LOCK_STEAL == 1
+	/* MAYBE_STEAL remains true */
+	steal_spins = val;
+#else
+	static DEFINE_MUTEX(lock);
+
+	/*
+	 * The lock slow path has a !maybe_stealers case that can assume
+	 * the head of queue will not see concurrent waiters. That waiter
+	 * is unsafe in the presence of stealers, so must keep them away
+	 * from one another.
+	 */
+
+	mutex_lock(&lock);
+	if (val && !steal_spins) {
+		maybe_stealers = true;
+		/* wait for queue head waiter to go away */
+		synchronize_rcu();
+		steal_spins = val;
+	} else if (!val && steal_spins) {
+		steal_spins = val;
+		/* wait for all possible stealers to go away */
+		synchronize_rcu();
+		maybe_stealers = false;
+	} else {
+		steal_spins = val;
+	}
+	mutex_unlock(&lock);
+#endif
+
+	return 0;
+}
+
+static int steal_spins_get(void *data, u64 *val)
+{
+	*val = steal_spins;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_steal_spins, steal_spins_get, steal_spins_set, "%llu\n");
+
+static int remote_steal_spins_set(void *data, u64 val)
+{
+	remote_steal_spins = val;
+
+	return 0;
+}
+
+static int remote_steal_spins_get(void *data, u64 *val)
+{
+	*val = remote_steal_spins;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_remote_steal_spins, remote_steal_spins_get, remote_steal_spins_set, "%llu\n");
+
+static int head_spins_set(void *data, u64 val)
+{
+	head_spins = val;
+
+	return 0;
+}
+
+static int head_spins_get(void *data, u64 *val)
+{
+	*val = head_spins;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_head_spins, head_spins_get, head_spins_set, "%llu\n");
+
+static int pv_yield_owner_set(void *data, u64 val)
+{
+	pv_yield_owner = !!val;
+
+	return 0;
+}
+
+static int pv_yield_owner_get(void *data, u64 *val)
+{
+	*val = pv_yield_owner;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_yield_owner, pv_yield_owner_get, pv_yield_owner_set, "%llu\n");
+
+static int pv_yield_allow_steal_set(void *data, u64 val)
+{
+	pv_yield_allow_steal = !!val;
+
+	return 0;
+}
+
+static int pv_yield_allow_steal_get(void *data, u64 *val)
+{
+	*val = pv_yield_allow_steal;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_yield_allow_steal, pv_yield_allow_steal_get, pv_yield_allow_steal_set, "%llu\n");
+
+static int pv_spin_on_preempted_owner_set(void *data, u64 val)
+{
+	pv_spin_on_preempted_owner = !!val;
+
+	return 0;
+}
+
+static int pv_spin_on_preempted_owner_get(void *data, u64 *val)
+{
+	*val = pv_spin_on_preempted_owner;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_spin_on_preempted_owner, pv_spin_on_preempted_owner_get, pv_spin_on_preempted_owner_set, "%llu\n");
+
+static int pv_sleepy_lock_set(void *data, u64 val)
+{
+	pv_sleepy_lock = !!val;
+
+	return 0;
+}
+
+static int pv_sleepy_lock_get(void *data, u64 *val)
+{
+	*val = pv_sleepy_lock;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_sleepy_lock, pv_sleepy_lock_get, pv_sleepy_lock_set, "%llu\n");
+
+static int pv_sleepy_lock_sticky_set(void *data, u64 val)
+{
+	pv_sleepy_lock_sticky = !!val;
+
+	return 0;
+}
+
+static int pv_sleepy_lock_sticky_get(void *data, u64 *val)
+{
+	*val = pv_sleepy_lock_sticky;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_sleepy_lock_sticky, pv_sleepy_lock_sticky_get, pv_sleepy_lock_sticky_set, "%llu\n");
+
+static int pv_sleepy_lock_interval_ns_set(void *data, u64 val)
+{
+	pv_sleepy_lock_interval_ns = val;
+
+	return 0;
+}
+
+static int pv_sleepy_lock_interval_ns_get(void *data, u64 *val)
+{
+	*val = pv_sleepy_lock_interval_ns;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_sleepy_lock_interval_ns, pv_sleepy_lock_interval_ns_get, pv_sleepy_lock_interval_ns_set, "%llu\n");
+
+static int pv_sleepy_lock_factor_set(void *data, u64 val)
+{
+	pv_sleepy_lock_factor = val;
+
+	return 0;
+}
+
+static int pv_sleepy_lock_factor_get(void *data, u64 *val)
+{
+	*val = pv_sleepy_lock_factor;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_sleepy_lock_factor, pv_sleepy_lock_factor_get, pv_sleepy_lock_factor_set, "%llu\n");
+
+static int pv_yield_prev_set(void *data, u64 val)
+{
+	pv_yield_prev = !!val;
+
+	return 0;
+}
+
+static int pv_yield_prev_get(void *data, u64 *val)
+{
+	*val = pv_yield_prev;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_yield_prev, pv_yield_prev_get, pv_yield_prev_set, "%llu\n");
+
+static int pv_yield_propagate_owner_set(void *data, u64 val)
+{
+	pv_yield_propagate_owner = !!val;
+
+	return 0;
+}
+
+static int pv_yield_propagate_owner_get(void *data, u64 *val)
+{
+	*val = pv_yield_propagate_owner;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_yield_propagate_owner, pv_yield_propagate_owner_get, pv_yield_propagate_owner_set, "%llu\n");
+
+static int pv_prod_head_set(void *data, u64 val)
+{
+	pv_prod_head = !!val;
+
+	return 0;
+}
+
+static int pv_prod_head_get(void *data, u64 *val)
+{
+	*val = pv_prod_head;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_pv_prod_head, pv_prod_head_get, pv_prod_head_set, "%llu\n");
+
+static __init int spinlock_debugfs_init(void)
+{
+	debugfs_create_file("qspl_steal_spins", 0600, arch_debugfs_dir, NULL, &fops_steal_spins);
+	debugfs_create_file("qspl_remote_steal_spins", 0600, arch_debugfs_dir, NULL, &fops_remote_steal_spins);
+	debugfs_create_file("qspl_head_spins", 0600, arch_debugfs_dir, NULL, &fops_head_spins);
+	if (is_shared_processor()) {
+		debugfs_create_file("qspl_pv_yield_owner", 0600, arch_debugfs_dir, NULL, &fops_pv_yield_owner);
+		debugfs_create_file("qspl_pv_yield_allow_steal", 0600, arch_debugfs_dir, NULL, &fops_pv_yield_allow_steal);
+		debugfs_create_file("qspl_pv_spin_on_preempted_owner", 0600, arch_debugfs_dir, NULL, &fops_pv_spin_on_preempted_owner);
+		debugfs_create_file("qspl_pv_sleepy_lock", 0600, arch_debugfs_dir, NULL, &fops_pv_sleepy_lock);
+		debugfs_create_file("qspl_pv_sleepy_lock_sticky", 0600, arch_debugfs_dir, NULL, &fops_pv_sleepy_lock_sticky);
+		debugfs_create_file("qspl_pv_sleepy_lock_interval_ns", 0600, arch_debugfs_dir, NULL, &fops_pv_sleepy_lock_interval_ns);
+		debugfs_create_file("qspl_pv_sleepy_lock_factor", 0600, arch_debugfs_dir, NULL, &fops_pv_sleepy_lock_factor);
+		debugfs_create_file("qspl_pv_yield_prev", 0600, arch_debugfs_dir, NULL, &fops_pv_yield_prev);
+		debugfs_create_file("qspl_pv_yield_propagate_owner", 0600, arch_debugfs_dir, NULL, &fops_pv_yield_propagate_owner);
+		debugfs_create_file("qspl_pv_prod_head", 0600, arch_debugfs_dir, NULL, &fops_pv_prod_head);
+	}
+
+	return 0;
+}
+device_initcall(spinlock_debugfs_init);