Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (2180f214) · Commits · 戴 / test

arch/arm64/include/asm/spinlock.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -11,4 +11,13 @@
		/* See include/linux/spinlock.h */
		#define smp_mb__after_spinlock() smp_mb()

		/*
		* Changing this will break osq_lock() thanks to the call inside
		* smp_cond_load_relaxed().
		*
		* See:
		* https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
		*/
		#define vcpu_is_preempted(cpu) false

		#endif /* __ASM_SPINLOCK_H */

+2 −2

Original line number	Diff line number	Diff line
		@@ -286,9 +286,9 @@ static int lockdep_stats_show(struct seq_file m, void v)
		seq_printf(m, " stack-trace entries: %11lu [max: %lu]\n",
		nr_stack_trace_entries, MAX_STACK_TRACE_ENTRIES);
		#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
		seq_printf(m, " number of stack traces: %llu\n",
		seq_printf(m, " number of stack traces: %11llu\n",
		lockdep_stack_trace_count());
		seq_printf(m, " number of stack hash chains: %llu\n",
		seq_printf(m, " number of stack hash chains: %11llu\n",
		lockdep_stack_hash_count());
		#endif
		seq_printf(m, " combined max dependencies: %11u\n",

+10 −13

Original line number	Diff line number	Diff line
		@@ -134,20 +134,17 @@ bool osq_lock(struct optimistic_spin_queue *lock)
		* cmpxchg in an attempt to undo our queueing.
		*/

		while (!READ_ONCE(node->locked)) {
		/*
		* If we need to reschedule bail... so we can block.
		* Use vcpu_is_preempted() to avoid waiting for a preempted
		* lock holder:
		* Wait to acquire the lock or cancelation. Note that need_resched()
		* will come with an IPI, which will wake smp_cond_load_relaxed() if it
		* is implemented with a monitor-wait. vcpu_is_preempted() relies on
		* polling, be careful.
		*/
		if (need_resched() \|\| vcpu_is_preempted(node_cpu(node->prev)))
		goto unqueue;

		cpu_relax();
		}
		if (smp_cond_load_relaxed(&node->locked, VAL \|\| need_resched() \|\|
		vcpu_is_preempted(node_cpu(node->prev))))
		return true;

		unqueue:
		/* unqueue */
		/*
		* Step - A -- stabilize @prev
		*

+7 −6

Original line number	Diff line number	Diff line
		@@ -31,14 +31,15 @@
		/*
		* The basic principle of a queue-based spinlock can best be understood
		* by studying a classic queue-based spinlock implementation called the
		* MCS lock. The paper below provides a good description for this kind
		* of lock.
		* MCS lock. A copy of the original MCS lock paper ("Algorithms for Scalable
		* Synchronization on Shared-Memory Multiprocessors by Mellor-Crummey and
		* Scott") is available at
		*
		* http://www.cise.ufl.edu/tr/DOC/REP-1992-71.pdf
		* https://bugzilla.kernel.org/show_bug.cgi?id=206115
		*
		* This queued spinlock implementation is based on the MCS lock, however to make
		* it fit the 4 bytes we assume spinlock_t to be, and preserve its existing
		* API, we must modify it somehow.
		* This queued spinlock implementation is based on the MCS lock, however to
		* make it fit the 4 bytes we assume spinlock_t to be, and preserve its
		* existing API, we must modify it somehow.
		*
		* In particular; where the traditional MCS lock consists of a tail pointer
		* (8 bytes) and needs the next pointer (another 8 bytes) of its own node to