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Date: Tue, 5 Jul 2022 00:38:09 +1000
From: Nicholas Piggin <npiggin@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Nicholas Piggin <npiggin@...il.com>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
Waiman Long <longman@...hat.com>,
Boqun Feng <boqun.feng@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 02/13] locking/qspinlock: inline mcs_spinlock functions into qspinlock
qspinlock uses mcs_spinlock for the struct type (.next, .locked, and the
misplaced .count), and arch_mcs_spin_{un}lock_contended(). These can be
trivially inlined into qspinlock, and the unused mcs_spinlock code
removed.
Signed-off-by: Nicholas Piggin <npiggin@...il.com>
---
arch/alpha/include/asm/Kbuild | 1 -
arch/arc/include/asm/Kbuild | 1 -
arch/arm/include/asm/mcs_spinlock.h | 24 ------
arch/arm64/include/asm/Kbuild | 1 -
arch/hexagon/include/asm/Kbuild | 1 -
arch/ia64/include/asm/Kbuild | 1 -
arch/m68k/include/asm/Kbuild | 1 -
arch/microblaze/include/asm/Kbuild | 1 -
arch/mips/include/asm/Kbuild | 1 -
arch/nios2/include/asm/Kbuild | 1 -
arch/parisc/include/asm/Kbuild | 1 -
arch/powerpc/include/asm/Kbuild | 1 -
arch/s390/include/asm/Kbuild | 1 -
arch/sh/include/asm/Kbuild | 1 -
arch/sparc/include/asm/Kbuild | 1 -
arch/um/include/asm/Kbuild | 1 -
arch/x86/include/asm/Kbuild | 1 -
arch/xtensa/include/asm/Kbuild | 1 -
include/asm-generic/mcs_spinlock.h | 13 ---
kernel/locking/mcs_spinlock.h | 121 ----------------------------
kernel/locking/qspinlock.c | 38 ++++-----
kernel/locking/qspinlock_paravirt.h | 55 ++++++-------
22 files changed, 43 insertions(+), 225 deletions(-)
delete mode 100644 arch/arm/include/asm/mcs_spinlock.h
delete mode 100644 include/asm-generic/mcs_spinlock.h
delete mode 100644 kernel/locking/mcs_spinlock.h
diff --git a/arch/alpha/include/asm/Kbuild b/arch/alpha/include/asm/Kbuild
index 42911c8340c7..d21cf7b3173a 100644
--- a/arch/alpha/include/asm/Kbuild
+++ b/arch/alpha/include/asm/Kbuild
@@ -3,4 +3,3 @@
generated-y += syscall_table.h
generic-y += export.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild
index 3c1afa524b9c..5ae4337a9301 100644
--- a/arch/arc/include/asm/Kbuild
+++ b/arch/arc/include/asm/Kbuild
@@ -1,6 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
generic-y += extable.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += parport.h
generic-y += user.h
diff --git a/arch/arm/include/asm/mcs_spinlock.h b/arch/arm/include/asm/mcs_spinlock.h
deleted file mode 100644
index 529d2cf4d06f..000000000000
--- a/arch/arm/include/asm/mcs_spinlock.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __ASM_MCS_LOCK_H
-#define __ASM_MCS_LOCK_H
-
-#ifdef CONFIG_SMP
-#include <asm/spinlock.h>
-
-/* MCS spin-locking. */
-#define arch_mcs_spin_lock_contended(lock) \
-do { \
- /* Ensure prior stores are observed before we enter wfe. */ \
- smp_mb(); \
- while (!(smp_load_acquire(lock))) \
- wfe(); \
-} while (0) \
-
-#define arch_mcs_spin_unlock_contended(lock) \
-do { \
- smp_store_release(lock, 1); \
- dsb_sev(); \
-} while (0)
-
-#endif /* CONFIG_SMP */
-#endif /* __ASM_MCS_LOCK_H */
diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index 5c8ee5a541d2..57e9ad366d25 100644
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -1,6 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
generic-y += early_ioremap.h
-generic-y += mcs_spinlock.h
generic-y += qrwlock.h
generic-y += qspinlock.h
generic-y += parport.h
diff --git a/arch/hexagon/include/asm/Kbuild b/arch/hexagon/include/asm/Kbuild
index 3ece3c93fe08..37bbf99f66d4 100644
--- a/arch/hexagon/include/asm/Kbuild
+++ b/arch/hexagon/include/asm/Kbuild
@@ -2,4 +2,3 @@
generic-y += extable.h
generic-y += iomap.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
diff --git a/arch/ia64/include/asm/Kbuild b/arch/ia64/include/asm/Kbuild
index f994c1daf9d4..a0198c12e339 100644
--- a/arch/ia64/include/asm/Kbuild
+++ b/arch/ia64/include/asm/Kbuild
@@ -1,5 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
generated-y += syscall_table.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += vtime.h
diff --git a/arch/m68k/include/asm/Kbuild b/arch/m68k/include/asm/Kbuild
index 1b720299deb1..8dbef73ce01d 100644
--- a/arch/m68k/include/asm/Kbuild
+++ b/arch/m68k/include/asm/Kbuild
@@ -3,5 +3,4 @@ generated-y += syscall_table.h
generic-y += export.h
generic-y += extable.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += spinlock.h
diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index a055f5dbe00a..7615a27e0851 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -3,7 +3,6 @@ generated-y += syscall_table.h
generic-y += cmpxchg.h
generic-y += extable.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += parport.h
generic-y += syscalls.h
generic-y += tlb.h
diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index dee172716581..65cedca08771 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -9,7 +9,6 @@ generated-y += unistd_nr_o32.h
generic-y += export.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += parport.h
generic-y += qrwlock.h
generic-y += qspinlock.h
diff --git a/arch/nios2/include/asm/Kbuild b/arch/nios2/include/asm/Kbuild
index 7fe7437555fb..5718eee9665c 100644
--- a/arch/nios2/include/asm/Kbuild
+++ b/arch/nios2/include/asm/Kbuild
@@ -2,6 +2,5 @@
generic-y += cmpxchg.h
generic-y += extable.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += spinlock.h
generic-y += user.h
diff --git a/arch/parisc/include/asm/Kbuild b/arch/parisc/include/asm/Kbuild
index e6e7f74c8ac9..1f0c28d74c88 100644
--- a/arch/parisc/include/asm/Kbuild
+++ b/arch/parisc/include/asm/Kbuild
@@ -2,5 +2,4 @@
generated-y += syscall_table_32.h
generated-y += syscall_table_64.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += user.h
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index bcf95ce0964f..813a8c3405ad 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -4,7 +4,6 @@ generated-y += syscall_table_64.h
generated-y += syscall_table_spu.h
generic-y += export.h
generic-y += kvm_types.h
-generic-y += mcs_spinlock.h
generic-y += qrwlock.h
generic-y += vtime.h
generic-y += early_ioremap.h
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 1a18d7b82f86..8b036a4ee2ca 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -7,4 +7,3 @@ generated-y += unistd_nr.h
generic-y += asm-offsets.h
generic-y += export.h
generic-y += kvm_types.h
-generic-y += mcs_spinlock.h
diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild
index fc44d9c88b41..3192f19bcf85 100644
--- a/arch/sh/include/asm/Kbuild
+++ b/arch/sh/include/asm/Kbuild
@@ -1,5 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
generated-y += syscall_table.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += parport.h
diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild
index 0b9d98ced34a..f0b913f7ba05 100644
--- a/arch/sparc/include/asm/Kbuild
+++ b/arch/sparc/include/asm/Kbuild
@@ -3,4 +3,3 @@ generated-y += syscall_table_32.h
generated-y += syscall_table_64.h
generic-y += export.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index b2d834a29f3a..04080c0c1aec 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -14,7 +14,6 @@ generic-y += hw_irq.h
generic-y += irq_regs.h
generic-y += irq_work.h
generic-y += kdebug.h
-generic-y += mcs_spinlock.h
generic-y += mmiowb.h
generic-y += module.lds.h
generic-y += param.h
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index 1e51650b79d7..beb7683f7b8f 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -10,4 +10,3 @@ generated-y += xen-hypercalls.h
generic-y += early_ioremap.h
generic-y += export.h
-generic-y += mcs_spinlock.h
diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild
index fa07c686cbcc..29ae65cb68c2 100644
--- a/arch/xtensa/include/asm/Kbuild
+++ b/arch/xtensa/include/asm/Kbuild
@@ -2,7 +2,6 @@
generated-y += syscall_table.h
generic-y += extable.h
generic-y += kvm_para.h
-generic-y += mcs_spinlock.h
generic-y += param.h
generic-y += parport.h
generic-y += qrwlock.h
diff --git a/include/asm-generic/mcs_spinlock.h b/include/asm-generic/mcs_spinlock.h
deleted file mode 100644
index 10cd4ffc6ba2..000000000000
--- a/include/asm-generic/mcs_spinlock.h
+++ /dev/null
@@ -1,13 +0,0 @@
-#ifndef __ASM_MCS_SPINLOCK_H
-#define __ASM_MCS_SPINLOCK_H
-
-/*
- * Architectures can define their own:
- *
- * arch_mcs_spin_lock_contended(l)
- * arch_mcs_spin_unlock_contended(l)
- *
- * See kernel/locking/mcs_spinlock.c.
- */
-
-#endif /* __ASM_MCS_SPINLOCK_H */
diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h
deleted file mode 100644
index 85251d8771d9..000000000000
--- a/kernel/locking/mcs_spinlock.h
+++ /dev/null
@@ -1,121 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * MCS lock defines
- *
- * This file contains the main data structure and API definitions of MCS lock.
- *
- * The MCS lock (proposed by Mellor-Crummey and Scott) is a simple spin-lock
- * with the desirable properties of being fair, and with each cpu trying
- * to acquire the lock spinning on a local variable.
- * It avoids expensive cache bounces that common test-and-set spin-lock
- * implementations incur.
- */
-#ifndef __LINUX_MCS_SPINLOCK_H
-#define __LINUX_MCS_SPINLOCK_H
-
-#include <asm/mcs_spinlock.h>
-
-struct mcs_spinlock {
- struct mcs_spinlock *next;
- int locked; /* 1 if lock acquired */
- int count; /* nesting count, see qspinlock.c */
-};
-
-#ifndef arch_mcs_spin_lock_contended
-/*
- * Using smp_cond_load_acquire() provides the acquire semantics
- * required so that subsequent operations happen after the
- * lock is acquired. Additionally, some architectures such as
- * ARM64 would like to do spin-waiting instead of purely
- * spinning, and smp_cond_load_acquire() provides that behavior.
- */
-#define arch_mcs_spin_lock_contended(l) \
-do { \
- smp_cond_load_acquire(l, VAL); \
-} while (0)
-#endif
-
-#ifndef arch_mcs_spin_unlock_contended
-/*
- * smp_store_release() provides a memory barrier to ensure all
- * operations in the critical section has been completed before
- * unlocking.
- */
-#define arch_mcs_spin_unlock_contended(l) \
- smp_store_release((l), 1)
-#endif
-
-/*
- * Note: the smp_load_acquire/smp_store_release pair is not
- * sufficient to form a full memory barrier across
- * cpus for many architectures (except x86) for mcs_unlock and mcs_lock.
- * For applications that need a full barrier across multiple cpus
- * with mcs_unlock and mcs_lock pair, smp_mb__after_unlock_lock() should be
- * used after mcs_lock.
- */
-
-/*
- * In order to acquire the lock, the caller should declare a local node and
- * pass a reference of the node to this function in addition to the lock.
- * If the lock has already been acquired, then this will proceed to spin
- * on this node->locked until the previous lock holder sets the node->locked
- * in mcs_spin_unlock().
- */
-static inline
-void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
-{
- struct mcs_spinlock *prev;
-
- /* Init node */
- node->locked = 0;
- node->next = NULL;
-
- /*
- * We rely on the full barrier with global transitivity implied by the
- * below xchg() to order the initialization stores above against any
- * observation of @node. And to provide the ACQUIRE ordering associated
- * with a LOCK primitive.
- */
- prev = xchg(lock, node);
- if (likely(prev == NULL)) {
- /*
- * Lock acquired, don't need to set node->locked to 1. Threads
- * only spin on its own node->locked value for lock acquisition.
- * However, since this thread can immediately acquire the lock
- * and does not proceed to spin on its own node->locked, this
- * value won't be used. If a debug mode is needed to
- * audit lock status, then set node->locked value here.
- */
- return;
- }
- WRITE_ONCE(prev->next, node);
-
- /* Wait until the lock holder passes the lock down. */
- arch_mcs_spin_lock_contended(&node->locked);
-}
-
-/*
- * Releases the lock. The caller should pass in the corresponding node that
- * was used to acquire the lock.
- */
-static inline
-void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
-{
- struct mcs_spinlock *next = READ_ONCE(node->next);
-
- if (likely(!next)) {
- /*
- * Release the lock by setting it to NULL
- */
- if (likely(cmpxchg_release(lock, node, NULL) == node))
- return;
- /* Wait until the next pointer is set */
- while (!(next = READ_ONCE(node->next)))
- cpu_relax();
- }
-
- /* Pass lock to next waiter. */
- arch_mcs_spin_unlock_contended(&next->locked);
-}
-
-#endif /* __LINUX_MCS_SPINLOCK_H */
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index a0fc21d99199..32f401e966ab 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -66,11 +66,10 @@
*
*/
-#include "mcs_spinlock.h"
#define MAX_NODES 4
/*
- * On 64-bit architectures, the mcs_spinlock structure will be 16 bytes in
+ * On 64-bit architectures, the qnode structure will be 16 bytes in
* size and four of them will fit nicely in one 64-byte cacheline. For
* pvqspinlock, however, we need more space for extra data. To accommodate
* that, we insert two more long words to pad it up to 32 bytes. IOW, only
@@ -80,7 +79,9 @@
* qspinlocks.
*/
struct qnode {
- struct mcs_spinlock mcs;
+ struct qnode *next;
+ int locked; /* 1 if lock acquired */
+ int count; /* nesting count */
#ifdef CONFIG_PARAVIRT_SPINLOCKS
int cpu;
u8 state;
@@ -124,18 +125,18 @@ static inline __pure u32 encode_tail(int cpu, int idx)
return tail;
}
-static inline __pure struct mcs_spinlock *decode_tail(u32 tail)
+static inline __pure struct qnode *decode_tail(u32 tail)
{
int cpu = (tail >> _Q_TAIL_CPU_OFFSET) - 1;
int idx = (tail & _Q_TAIL_IDX_MASK) >> _Q_TAIL_IDX_OFFSET;
- return per_cpu_ptr(&qnodes[idx].mcs, cpu);
+ return per_cpu_ptr(&qnodes[idx], cpu);
}
static inline __pure
-struct mcs_spinlock *grab_mcs_node(struct mcs_spinlock *base, int idx)
+struct qnode *grab_qnode(struct qnode *base, int idx)
{
- return &((struct qnode *)base + idx)->mcs;
+ return &base[idx];
}
#define _Q_LOCKED_PENDING_MASK (_Q_LOCKED_MASK | _Q_PENDING_MASK)
@@ -271,13 +272,13 @@ static __always_inline void set_locked(struct qspinlock *lock)
* all the PV callbacks.
*/
-static __always_inline void __pv_init_node(struct mcs_spinlock *node) { }
-static __always_inline void __pv_wait_node(struct mcs_spinlock *node,
- struct mcs_spinlock *prev) { }
+static __always_inline void __pv_init_node(struct qnode *node) { }
+static __always_inline void __pv_wait_node(struct qnode *node,
+ struct qnode *prev) { }
static __always_inline void __pv_kick_node(struct qspinlock *lock,
- struct mcs_spinlock *node) { }
+ struct qnode *node) { }
static __always_inline u32 __pv_wait_head_or_lock(struct qspinlock *lock,
- struct mcs_spinlock *node)
+ struct qnode *node)
{ return 0; }
#define pv_enabled() false
@@ -316,7 +317,7 @@ static __always_inline u32 __pv_wait_head_or_lock(struct qspinlock *lock,
*/
void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
{
- struct mcs_spinlock *prev, *next, *node;
+ struct qnode *prev, *next, *node;
u32 old, tail;
int idx;
@@ -399,7 +400,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
queue:
lockevent_inc(lock_slowpath);
pv_queue:
- node = this_cpu_ptr(&qnodes[0].mcs);
+ node = this_cpu_ptr(&qnodes[0]);
idx = node->count++;
tail = encode_tail(smp_processor_id(), idx);
@@ -421,7 +422,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
goto release;
}
- node = grab_mcs_node(node, idx);
+ node = grab_qnode(node, idx);
/*
* Keep counts of non-zero index values:
@@ -475,7 +476,8 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
WRITE_ONCE(prev->next, node);
pv_wait_node(node, prev);
- arch_mcs_spin_lock_contended(&node->locked);
+ /* Wait for mcs node lock to be released */
+ smp_cond_load_acquire(&node->locked, VAL);
/*
* While waiting for the MCS lock, the next pointer may have
@@ -554,7 +556,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
if (!next)
next = smp_cond_load_relaxed(&node->next, (VAL));
- arch_mcs_spin_unlock_contended(&next->locked);
+ smp_store_release(&next->locked, 1); /* unlock the mcs node lock */
pv_kick_node(lock, next);
release:
@@ -563,7 +565,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
/*
* release the node
*/
- __this_cpu_dec(qnodes[0].mcs.count);
+ __this_cpu_dec(qnodes[0].count);
}
EXPORT_SYMBOL(queued_spin_lock_slowpath);
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index b6a175155f36..cce3d3dde216 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -267,16 +267,12 @@ pv_wait_early(struct qnode *prev, int loop)
}
/*
- * Initialize the PV part of the mcs_spinlock node.
+ * Initialize the PV part of the qnode.
*/
-static void pv_init_node(struct mcs_spinlock *node)
+static void pv_init_node(struct qnode *node)
{
- struct qnode *pn = (struct qnode *)node;
-
- BUILD_BUG_ON(sizeof(struct qnode) > sizeof(struct qnode));
-
- pn->cpu = smp_processor_id();
- pn->state = vcpu_running;
+ node->cpu = smp_processor_id();
+ node->state = vcpu_running;
}
/*
@@ -284,10 +280,8 @@ static void pv_init_node(struct mcs_spinlock *node)
* pv_kick_node() is used to set _Q_SLOW_VAL and fill in hash table on its
* behalf.
*/
-static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
+static void pv_wait_node(struct qnode *node, struct qnode *prev)
{
- struct qnode *pn = (struct qnode *)node;
- struct qnode *pp = (struct qnode *)prev;
int loop;
bool wait_early;
@@ -295,7 +289,7 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
for (wait_early = false, loop = SPIN_THRESHOLD; loop; loop--) {
if (READ_ONCE(node->locked))
return;
- if (pv_wait_early(pp, loop)) {
+ if (pv_wait_early(prev, loop)) {
wait_early = true;
break;
}
@@ -303,20 +297,20 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
}
/*
- * Order pn->state vs pn->locked thusly:
+ * Order node->state vs node->locked thusly:
*
- * [S] pn->state = vcpu_halted [S] next->locked = 1
- * MB MB
- * [L] pn->locked [RmW] pn->state = vcpu_hashed
+ * [S] node->state = vcpu_halted [S] next->locked = 1
+ * MB MB
+ * [L] node->locked [RmW] node->state = vcpu_hashed
*
* Matches the cmpxchg() from pv_kick_node().
*/
- smp_store_mb(pn->state, vcpu_halted);
+ smp_store_mb(node->state, vcpu_halted);
if (!READ_ONCE(node->locked)) {
lockevent_inc(pv_wait_node);
lockevent_cond_inc(pv_wait_early, wait_early);
- pv_wait(&pn->state, vcpu_halted);
+ pv_wait(&node->state, vcpu_halted);
}
/*
@@ -324,7 +318,7 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
* value so that pv_wait_head_or_lock() knows to not also try
* to hash this lock.
*/
- cmpxchg(&pn->state, vcpu_halted, vcpu_running);
+ cmpxchg(&node->state, vcpu_halted, vcpu_running);
/*
* If the locked flag is still not set after wakeup, it is a
@@ -351,10 +345,8 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
* such that they're waiting in pv_wait_head_or_lock(), this avoids a
* wake/sleep cycle.
*/
-static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node)
+static void pv_kick_node(struct qspinlock *lock, struct qnode *node)
{
- struct qnode *pn = (struct qnode *)node;
-
/*
* If the vCPU is indeed halted, advance its state to match that of
* pv_wait_node(). If OTOH this fails, the vCPU was running and will
@@ -363,15 +355,15 @@ static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node)
* Matches with smp_store_mb() and cmpxchg() in pv_wait_node()
*
* The write to next->locked in arch_mcs_spin_unlock_contended()
- * must be ordered before the read of pn->state in the cmpxchg()
+ * must be ordered before the read of node->state in the cmpxchg()
* below for the code to work correctly. To guarantee full ordering
* irrespective of the success or failure of the cmpxchg(),
* a relaxed version with explicit barrier is used. The control
- * dependency will order the reading of pn->state before any
+ * dependency will order the reading of node->state before any
* subsequent writes.
*/
smp_mb__before_atomic();
- if (cmpxchg_relaxed(&pn->state, vcpu_halted, vcpu_hashed)
+ if (cmpxchg_relaxed(&node->state, vcpu_halted, vcpu_hashed)
!= vcpu_halted)
return;
@@ -383,7 +375,7 @@ static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node)
* needed.
*/
WRITE_ONCE(lock->locked, _Q_SLOW_VAL);
- (void)pv_hash(lock, pn);
+ (void)pv_hash(lock, node);
}
/*
@@ -394,9 +386,8 @@ static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node)
* The current value of the lock will be returned for additional processing.
*/
static u32
-pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
+pv_wait_head_or_lock(struct qspinlock *lock, struct qnode *node)
{
- struct qnode *pn = (struct qnode *)node;
struct qspinlock **lp = NULL;
int waitcnt = 0;
int loop;
@@ -405,7 +396,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
* If pv_kick_node() already advanced our state, we don't need to
* insert ourselves into the hash table anymore.
*/
- if (READ_ONCE(pn->state) == vcpu_hashed)
+ if (READ_ONCE(node->state) == vcpu_hashed)
lp = (struct qspinlock **)1;
/*
@@ -418,7 +409,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
* Set correct vCPU state to be used by queue node wait-early
* mechanism.
*/
- WRITE_ONCE(pn->state, vcpu_running);
+ WRITE_ONCE(node->state, vcpu_running);
/*
* Set the pending bit in the active lock spinning loop to
@@ -434,7 +425,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
if (!lp) { /* ONCE */
- lp = pv_hash(lock, pn);
+ lp = pv_hash(lock, node);
/*
* We must hash before setting _Q_SLOW_VAL, such that
@@ -458,7 +449,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
goto gotlock;
}
}
- WRITE_ONCE(pn->state, vcpu_hashed);
+ WRITE_ONCE(node->state, vcpu_hashed);
lockevent_inc(pv_wait_head);
lockevent_cond_inc(pv_wait_again, waitcnt);
pv_wait(&lock->locked, _Q_SLOW_VAL);
--
2.35.1
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