rcu: Expunge lingering references to CONFIG_CLASSIC_RCU, optimize on !SMP (b560d8ad) · Commits · 戴 / test

A couple of references to CONFIG_CLASSIC_RCU have survived. Although these are harmless, it is past time for them to go. The one in hardirq.h is strictly a readability problem. The two in pagemap.h appear to disable a !SMP performance optimization (which this patch re-enables). This does raise the issue as to whether pagemap.h should really be referring to the CPU implementation. Long term, I intend to make the RCU implementation driven by CONFIG_PREEMPT, at which point these should change from defined(CONFIG_TREE_RCU) to !defined(CONFIG_PREEMPT). In the meantime, is there something else that could be done in pagemap.h? Signed-off-by:

Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josht@linux.vnet.ibm.com Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org LKML-Reference: <20090822050851.GA8414@linux.vnet.ibm.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

include/linux/hardirq.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -132,7 +132,7 @@ static inline void account_system_vtime(struct task_struct *tsk)
		}
		#endif

		#if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU)
		#if defined(CONFIG_NO_HZ)
		extern void rcu_irq_enter(void);
		extern void rcu_irq_exit(void);
		extern void rcu_nmi_enter(void);
		@@ -142,7 +142,7 @@ extern void rcu_nmi_exit(void);
		# define rcu_irq_exit() do { } while (0)
		# define rcu_nmi_enter() do { } while (0)
		# define rcu_nmi_exit() do { } while (0)
		#endif /* #if defined(CONFIG_NO_HZ) && !defined(CONFIG_CLASSIC_RCU) */
		#endif /* #if defined(CONFIG_NO_HZ) */

		/*
		* It is safe to do non-atomic ops on ->hardirq_context,

include/linux/pagemap.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -132,7 +132,7 @@ static inline int page_cache_get_speculative(struct page *page)
		{
		VM_BUG_ON(in_interrupt());

		#if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU)
		#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
		# ifdef CONFIG_PREEMPT
		VM_BUG_ON(!in_atomic());
		# endif
		@@ -170,7 +170,7 @@ static inline int page_cache_add_speculative(struct page *page, int count)
		{
		VM_BUG_ON(in_interrupt());

		#if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU)
		#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
		# ifdef CONFIG_PREEMPT
		VM_BUG_ON(!in_atomic());
		# endif

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