Merge branches 'doc.2017.04.12a', 'fixes.2017.04.19a' and 'srcu.2017.04.21a' into HEAD (f2094107) · Commits · 戴 / test

Documentation/RCU/00-INDEX

+1 −1

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		@@ -17,7 +17,7 @@ rcu_dereference.txt
		rcubarrier.txt
		- RCU and Unloadable Modules
		rculist_nulls.txt
		- RCU list primitives for use with SLAB_DESTROY_BY_RCU
		- RCU list primitives for use with SLAB_TYPESAFE_BY_RCU
		rcuref.txt
		- Reference-count design for elements of lists/arrays protected by RCU
		rcu.txt

Documentation/RCU/Design/Data-Structures/Data-Structures.html

+25 −1

Original line number	Diff line number	Diff line
		@@ -1185,6 +1185,9 @@ Its fields are as follows:
		1 int dynticks_nesting;
		2 int dynticks_nmi_nesting;
		3 atomic_t dynticks;
		4 bool rcu_need_heavy_qs;
		5 unsigned long rcu_qs_ctr;
		6 bool rcu_urgent_qs;
		</pre>

		<p>The <tt>->dynticks_nesting</tt> field counts the
		@@ -1198,11 +1201,32 @@ NMIs are counted by the <tt>->dynticks_nmi_nesting</tt>
		field, except that NMIs that interrupt non-dyntick-idle execution
		are not counted.

		</p><p>Finally, the <tt>->dynticks</tt> field counts the corresponding
		</p><p>The <tt>->dynticks</tt> field counts the corresponding
		CPU's transitions to and from dyntick-idle mode, so that this counter
		has an even value when the CPU is in dyntick-idle mode and an odd
		value otherwise.

		</p><p>The <tt>->rcu_need_heavy_qs</tt> field is used
		to record the fact that the RCU core code would really like to
		see a quiescent state from the corresponding CPU, so much so that
		it is willing to call for heavy-weight dyntick-counter operations.
		This flag is checked by RCU's context-switch and <tt>cond_resched()</tt>
		code, which provide a momentary idle sojourn in response.

		</p><p>The <tt>->rcu_qs_ctr</tt> field is used to record
		quiescent states from <tt>cond_resched()</tt>.
		Because <tt>cond_resched()</tt> can execute quite frequently, this
		must be quite lightweight, as in a non-atomic increment of this
		per-CPU field.

		</p><p>Finally, the <tt>->rcu_urgent_qs</tt> field is used to record
		the fact that the RCU core code would really like to see a quiescent
		state from the corresponding CPU, with the various other fields indicating
		just how badly RCU wants this quiescent state.
		This flag is checked by RCU's context-switch and <tt>cond_resched()</tt>
		code, which, if nothing else, non-atomically increment <tt>->rcu_qs_ctr</tt>
		in response.

		<table>
		<tr><th> </th></tr>
		<tr><th align="left">Quick Quiz:</th></tr>

Documentation/RCU/rculist_nulls.txt

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		Using hlist_nulls to protect read-mostly linked lists and
		objects using SLAB_DESTROY_BY_RCU allocations.
		objects using SLAB_TYPESAFE_BY_RCU allocations.

		Please read the basics in Documentation/RCU/listRCU.txt

		@@ -7,7 +7,7 @@ Using special makers (called 'nulls') is a convenient way
		to solve following problem :

		A typical RCU linked list managing objects which are
		allocated with SLAB_DESTROY_BY_RCU kmem_cache can
		allocated with SLAB_TYPESAFE_BY_RCU kmem_cache can
		use following algos :

		1) Lookup algo
		@@ -96,7 +96,7 @@ unlock_chain(); // typically a spin_unlock()
		3) Remove algo
		--------------
		Nothing special here, we can use a standard RCU hlist deletion.
		But thanks to SLAB_DESTROY_BY_RCU, beware a deleted object can be reused
		But thanks to SLAB_TYPESAFE_BY_RCU, beware a deleted object can be reused
		very very fast (before the end of RCU grace period)

		if (put_last_reference_on(obj) {

Documentation/RCU/whatisRCU.txt

+2 −1

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		@@ -928,7 +928,8 @@ d. Do you need RCU grace periods to complete even in the face

		e. Is your workload too update-intensive for normal use of
		RCU, but inappropriate for other synchronization mechanisms?
		If so, consider SLAB_DESTROY_BY_RCU. But please be careful!
		If so, consider SLAB_TYPESAFE_BY_RCU (which was originally
		named SLAB_DESTROY_BY_RCU). But please be careful!

		f. Do you need read-side critical sections that are respected
		even though they are in the middle of the idle loop, during

arch/Kconfig

+3 −0

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		@@ -320,6 +320,9 @@ config HAVE_CMPXCHG_LOCAL
		config HAVE_CMPXCHG_DOUBLE
		bool

		config ARCH_WEAK_RELEASE_ACQUIRE
		bool

		config ARCH_WANT_IPC_PARSE_VERSION
		bool

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