rcu: define __rcu address space modifier for sparse
This commit provides definitions for the __rcu annotation defined earlier. This annotation permits sparse to check for correct use of RCU-protected pointers. If a pointer that is annotated with __rcu is accessed directly (as opposed to via rcu_dereference(), rcu_assign_pointer(), or one of their variants), sparse can be made to complain. To enable such complaints, use the new default-disabled CONFIG_SPARSE_RCU_POINTER kernel configuration option. Please note that these sparse complaints are intended to be a debugging aid, -not- a code-style-enforcement mechanism. There are special rcu_dereference_protected() and rcu_access_pointer() accessors for use when RCU read-side protection is not required, for example, when no other CPU has access to the data structure in question or while the current CPU hold the update-side lock. This patch also updates a number of docbook comments that were showing their age. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Christopher Li <sparse@chrisli.org> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney
parent
d34a16661e
commit
ca5ecddfa8
5 changed files with 260 additions and 148 deletions
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@ -16,7 +16,11 @@
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# define __release(x) __context__(x,-1)
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# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
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# define __percpu __attribute__((noderef, address_space(3)))
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#ifdef CONFIG_SPARSE_RCU_POINTER
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# define __rcu __attribute__((noderef, address_space(4)))
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#else
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# define __rcu
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#endif
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extern void __chk_user_ptr(const volatile void __user *);
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extern void __chk_io_ptr(const volatile void __iomem *);
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#else
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@ -41,6 +41,7 @@
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#include <linux/lockdep.h>
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#include <linux/completion.h>
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#include <linux/debugobjects.h>
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#include <linux/compiler.h>
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#ifdef CONFIG_RCU_TORTURE_TEST
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extern int rcutorture_runnable; /* for sysctl */
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@ -120,14 +121,15 @@ extern struct lockdep_map rcu_sched_lock_map;
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extern int debug_lockdep_rcu_enabled(void);
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/**
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* rcu_read_lock_held - might we be in RCU read-side critical section?
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* rcu_read_lock_held() - might we be in RCU read-side critical section?
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*
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* If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU
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* read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC,
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* this assumes we are in an RCU read-side critical section unless it can
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* prove otherwise.
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* prove otherwise. This is useful for debug checks in functions that
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* require that they be called within an RCU read-side critical section.
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*
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* Check debug_lockdep_rcu_enabled() to prevent false positives during boot
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* Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
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* and while lockdep is disabled.
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*/
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static inline int rcu_read_lock_held(void)
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@ -144,14 +146,16 @@ static inline int rcu_read_lock_held(void)
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extern int rcu_read_lock_bh_held(void);
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/**
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* rcu_read_lock_sched_held - might we be in RCU-sched read-side critical section?
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* rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
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*
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* If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
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* RCU-sched read-side critical section. In absence of
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* CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
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* critical section unless it can prove otherwise. Note that disabling
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* of preemption (including disabling irqs) counts as an RCU-sched
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* read-side critical section.
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* read-side critical section. This is useful for debug checks in functions
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* that required that they be called within an RCU-sched read-side
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* critical section.
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*
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* Check debug_lockdep_rcu_enabled() to prevent false positives during boot
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* and while lockdep is disabled.
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@ -220,41 +224,155 @@ extern int rcu_my_thread_group_empty(void);
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} \
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} while (0)
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#else /* #ifdef CONFIG_PROVE_RCU */
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#define __do_rcu_dereference_check(c) do { } while (0)
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#endif /* #else #ifdef CONFIG_PROVE_RCU */
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/*
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* Helper functions for rcu_dereference_check(), rcu_dereference_protected()
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* and rcu_assign_pointer(). Some of these could be folded into their
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* callers, but they are left separate in order to ease introduction of
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* multiple flavors of pointers to match the multiple flavors of RCU
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* (e.g., __rcu_bh, * __rcu_sched, and __srcu), should this make sense in
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* the future.
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*/
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#define __rcu_access_pointer(p, space) \
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({ \
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typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
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(void) (((typeof (*p) space *)p) == p); \
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((typeof(*p) __force __kernel *)(_________p1)); \
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})
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#define __rcu_dereference_check(p, c, space) \
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({ \
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typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
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__do_rcu_dereference_check(c); \
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(void) (((typeof (*p) space *)p) == p); \
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smp_read_barrier_depends(); \
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((typeof(*p) __force __kernel *)(_________p1)); \
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})
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#define __rcu_dereference_protected(p, c, space) \
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({ \
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__do_rcu_dereference_check(c); \
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(void) (((typeof (*p) space *)p) == p); \
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((typeof(*p) __force __kernel *)(p)); \
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})
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#define __rcu_dereference_index_check(p, c) \
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({ \
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typeof(p) _________p1 = ACCESS_ONCE(p); \
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__do_rcu_dereference_check(c); \
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smp_read_barrier_depends(); \
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(_________p1); \
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})
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#define __rcu_assign_pointer(p, v, space) \
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({ \
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if (!__builtin_constant_p(v) || \
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((v) != NULL)) \
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smp_wmb(); \
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(p) = (typeof(*v) __force space *)(v); \
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})
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/**
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* rcu_dereference_check - rcu_dereference with debug checking
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* rcu_access_pointer() - fetch RCU pointer with no dereferencing
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* @p: The pointer to read
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*
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* Return the value of the specified RCU-protected pointer, but omit the
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* smp_read_barrier_depends() and keep the ACCESS_ONCE(). This is useful
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* when the value of this pointer is accessed, but the pointer is not
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* dereferenced, for example, when testing an RCU-protected pointer against
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* NULL. Although rcu_access_pointer() may also be used in cases where
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* update-side locks prevent the value of the pointer from changing, you
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* should instead use rcu_dereference_protected() for this use case.
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*/
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#define rcu_access_pointer(p) __rcu_access_pointer((p), __rcu)
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/**
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* rcu_dereference_check() - rcu_dereference with debug checking
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* @p: The pointer to read, prior to dereferencing
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* @c: The conditions under which the dereference will take place
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*
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* Do an rcu_dereference(), but check that the conditions under which the
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* dereference will take place are correct. Typically the conditions indicate
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* the various locking conditions that should be held at that point. The check
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* should return true if the conditions are satisfied.
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* dereference will take place are correct. Typically the conditions
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* indicate the various locking conditions that should be held at that
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* point. The check should return true if the conditions are satisfied.
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* An implicit check for being in an RCU read-side critical section
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* (rcu_read_lock()) is included.
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*
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* For example:
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*
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* bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
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* lockdep_is_held(&foo->lock));
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* bar = rcu_dereference_check(foo->bar, lockdep_is_held(&foo->lock));
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*
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* could be used to indicate to lockdep that foo->bar may only be dereferenced
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* if either the RCU read lock is held, or that the lock required to replace
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* if either rcu_read_lock() is held, or that the lock required to replace
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* the bar struct at foo->bar is held.
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*
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* Note that the list of conditions may also include indications of when a lock
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* need not be held, for example during initialisation or destruction of the
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* target struct:
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*
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* bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
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* lockdep_is_held(&foo->lock) ||
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* bar = rcu_dereference_check(foo->bar, lockdep_is_held(&foo->lock) ||
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* atomic_read(&foo->usage) == 0);
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*
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* Inserts memory barriers on architectures that require them
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* (currently only the Alpha), prevents the compiler from refetching
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* (and from merging fetches), and, more importantly, documents exactly
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* which pointers are protected by RCU and checks that the pointer is
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* annotated as __rcu.
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*/
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#define rcu_dereference_check(p, c) \
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({ \
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__do_rcu_dereference_check(c); \
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rcu_dereference_raw(p); \
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})
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__rcu_dereference_check((p), rcu_read_lock_held() || (c), __rcu)
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/**
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* rcu_dereference_protected - fetch RCU pointer when updates prevented
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* rcu_dereference_bh_check() - rcu_dereference_bh with debug checking
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* @p: The pointer to read, prior to dereferencing
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* @c: The conditions under which the dereference will take place
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*
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* This is the RCU-bh counterpart to rcu_dereference_check().
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*/
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#define rcu_dereference_bh_check(p, c) \
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__rcu_dereference_check((p), rcu_read_lock_bh_held() || (c), __rcu)
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/**
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* rcu_dereference_sched_check() - rcu_dereference_sched with debug checking
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* @p: The pointer to read, prior to dereferencing
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* @c: The conditions under which the dereference will take place
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*
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* This is the RCU-sched counterpart to rcu_dereference_check().
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*/
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#define rcu_dereference_sched_check(p, c) \
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__rcu_dereference_check((p), rcu_read_lock_sched_held() || (c), \
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__rcu)
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#define rcu_dereference_raw(p) rcu_dereference_check(p, 1) /*@@@ needed? @@@*/
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/**
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* rcu_dereference_index_check() - rcu_dereference for indices with debug checking
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* @p: The pointer to read, prior to dereferencing
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* @c: The conditions under which the dereference will take place
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*
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* Similar to rcu_dereference_check(), but omits the sparse checking.
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* This allows rcu_dereference_index_check() to be used on integers,
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* which can then be used as array indices. Attempting to use
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* rcu_dereference_check() on an integer will give compiler warnings
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* because the sparse address-space mechanism relies on dereferencing
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* the RCU-protected pointer. Dereferencing integers is not something
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* that even gcc will put up with.
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*
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* Note that this function does not implicitly check for RCU read-side
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* critical sections. If this function gains lots of uses, it might
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* make sense to provide versions for each flavor of RCU, but it does
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* not make sense as of early 2010.
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*/
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#define rcu_dereference_index_check(p, c) \
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__rcu_dereference_index_check((p), (c))
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/**
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* rcu_dereference_protected() - fetch RCU pointer when updates prevented
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* @p: The pointer to read, prior to dereferencing
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* @c: The conditions under which the dereference will take place
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*
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* Return the value of the specified RCU-protected pointer, but omit
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* both the smp_read_barrier_depends() and the ACCESS_ONCE(). This
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@ -263,35 +381,61 @@ extern int rcu_my_thread_group_empty(void);
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* prevent the compiler from repeating this reference or combining it
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* with other references, so it should not be used without protection
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* of appropriate locks.
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*
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* This function is only for update-side use. Using this function
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* when protected only by rcu_read_lock() will result in infrequent
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* but very ugly failures.
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*/
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#define rcu_dereference_protected(p, c) \
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({ \
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__do_rcu_dereference_check(c); \
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(p); \
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})
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#else /* #ifdef CONFIG_PROVE_RCU */
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#define rcu_dereference_check(p, c) rcu_dereference_raw(p)
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#define rcu_dereference_protected(p, c) (p)
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#endif /* #else #ifdef CONFIG_PROVE_RCU */
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__rcu_dereference_protected((p), (c), __rcu)
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/**
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* rcu_access_pointer - fetch RCU pointer with no dereferencing
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* rcu_dereference_bh_protected() - fetch RCU-bh pointer when updates prevented
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* @p: The pointer to read, prior to dereferencing
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* @c: The conditions under which the dereference will take place
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*
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* Return the value of the specified RCU-protected pointer, but omit the
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* smp_read_barrier_depends() and keep the ACCESS_ONCE(). This is useful
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* when the value of this pointer is accessed, but the pointer is not
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* dereferenced, for example, when testing an RCU-protected pointer against
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* NULL. This may also be used in cases where update-side locks prevent
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* the value of the pointer from changing, but rcu_dereference_protected()
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* is a lighter-weight primitive for this use case.
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* This is the RCU-bh counterpart to rcu_dereference_protected().
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*/
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#define rcu_access_pointer(p) ACCESS_ONCE(p)
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#define rcu_dereference_bh_protected(p, c) \
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__rcu_dereference_protected((p), (c), __rcu)
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/**
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* rcu_read_lock - mark the beginning of an RCU read-side critical section.
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* rcu_dereference_sched_protected() - fetch RCU-sched pointer when updates prevented
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* @p: The pointer to read, prior to dereferencing
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* @c: The conditions under which the dereference will take place
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*
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* This is the RCU-sched counterpart to rcu_dereference_protected().
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*/
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#define rcu_dereference_sched_protected(p, c) \
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__rcu_dereference_protected((p), (c), __rcu)
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/**
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* rcu_dereference() - fetch RCU-protected pointer for dereferencing
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* @p: The pointer to read, prior to dereferencing
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*
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* This is a simple wrapper around rcu_dereference_check().
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*/
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#define rcu_dereference(p) rcu_dereference_check(p, 0)
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/**
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* rcu_dereference_bh() - fetch an RCU-bh-protected pointer for dereferencing
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* @p: The pointer to read, prior to dereferencing
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*
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* Makes rcu_dereference_check() do the dirty work.
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*/
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#define rcu_dereference_bh(p) rcu_dereference_bh_check(p, 0)
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/**
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* rcu_dereference_sched() - fetch RCU-sched-protected pointer for dereferencing
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* @p: The pointer to read, prior to dereferencing
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*
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* Makes rcu_dereference_check() do the dirty work.
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*/
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#define rcu_dereference_sched(p) rcu_dereference_sched_check(p, 0)
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/**
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* rcu_read_lock() - mark the beginning of an RCU read-side critical section
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*
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* When synchronize_rcu() is invoked on one CPU while other CPUs
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* are within RCU read-side critical sections, then the
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@ -337,7 +481,7 @@ static inline void rcu_read_lock(void)
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*/
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/**
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* rcu_read_unlock - marks the end of an RCU read-side critical section.
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* rcu_read_unlock() - marks the end of an RCU read-side critical section.
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*
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* See rcu_read_lock() for more information.
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*/
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@ -349,15 +493,16 @@ static inline void rcu_read_unlock(void)
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}
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/**
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* rcu_read_lock_bh - mark the beginning of a softirq-only RCU critical section
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* rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section
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*
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* This is equivalent of rcu_read_lock(), but to be used when updates
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* are being done using call_rcu_bh(). Since call_rcu_bh() callbacks
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* consider completion of a softirq handler to be a quiescent state,
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* a process in RCU read-side critical section must be protected by
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* disabling softirqs. Read-side critical sections in interrupt context
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* can use just rcu_read_lock().
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*
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* are being done using call_rcu_bh() or synchronize_rcu_bh(). Since
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* both call_rcu_bh() and synchronize_rcu_bh() consider completion of a
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* softirq handler to be a quiescent state, a process in RCU read-side
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* critical section must be protected by disabling softirqs. Read-side
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* critical sections in interrupt context can use just rcu_read_lock(),
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* though this should at least be commented to avoid confusing people
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* reading the code.
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*/
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static inline void rcu_read_lock_bh(void)
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{
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@ -379,13 +524,12 @@ static inline void rcu_read_unlock_bh(void)
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}
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/**
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* rcu_read_lock_sched - mark the beginning of a RCU-classic critical section
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* rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section
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*
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* Should be used with either
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* - synchronize_sched()
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* or
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* - call_rcu_sched() and rcu_barrier_sched()
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* on the write-side to insure proper synchronization.
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* This is equivalent of rcu_read_lock(), but to be used when updates
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* are being done using call_rcu_sched() or synchronize_rcu_sched().
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* Read-side critical sections can also be introduced by anything that
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* disables preemption, including local_irq_disable() and friends.
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*/
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static inline void rcu_read_lock_sched(void)
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{
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@ -420,54 +564,14 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
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preempt_enable_notrace();
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}
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/**
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* rcu_dereference_raw - fetch an RCU-protected pointer
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* rcu_assign_pointer() - assign to RCU-protected pointer
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* @p: pointer to assign to
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* @v: value to assign (publish)
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*
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* The caller must be within some flavor of RCU read-side critical
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* section, or must be otherwise preventing the pointer from changing,
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* for example, by holding an appropriate lock. This pointer may later
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* be safely dereferenced. It is the caller's responsibility to have
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* done the right thing, as this primitive does no checking of any kind.
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*
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* Inserts memory barriers on architectures that require them
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* (currently only the Alpha), and, more importantly, documents
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* exactly which pointers are protected by RCU.
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*/
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#define rcu_dereference_raw(p) ({ \
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typeof(p) _________p1 = ACCESS_ONCE(p); \
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smp_read_barrier_depends(); \
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(_________p1); \
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})
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/**
|
||||
* rcu_dereference - fetch an RCU-protected pointer, checking for RCU
|
||||
*
|
||||
* Makes rcu_dereference_check() do the dirty work.
|
||||
*/
|
||||
#define rcu_dereference(p) \
|
||||
rcu_dereference_check(p, rcu_read_lock_held())
|
||||
|
||||
/**
|
||||
* rcu_dereference_bh - fetch an RCU-protected pointer, checking for RCU-bh
|
||||
*
|
||||
* Makes rcu_dereference_check() do the dirty work.
|
||||
*/
|
||||
#define rcu_dereference_bh(p) \
|
||||
rcu_dereference_check(p, rcu_read_lock_bh_held())
|
||||
|
||||
/**
|
||||
* rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched
|
||||
*
|
||||
* Makes rcu_dereference_check() do the dirty work.
|
||||
*/
|
||||
#define rcu_dereference_sched(p) \
|
||||
rcu_dereference_check(p, rcu_read_lock_sched_held())
|
||||
|
||||
/**
|
||||
* rcu_assign_pointer - assign (publicize) a pointer to a newly
|
||||
* initialized structure that will be dereferenced by RCU read-side
|
||||
* critical sections. Returns the value assigned.
|
||||
* Assigns the specified value to the specified RCU-protected
|
||||
* pointer, ensuring that any concurrent RCU readers will see
|
||||
* any prior initialization. Returns the value assigned.
|
||||
*
|
||||
* Inserts memory barriers on architectures that require them
|
||||
* (pretty much all of them other than x86), and also prevents
|
||||
|
|
@ -476,14 +580,17 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
|
|||
* call documents which pointers will be dereferenced by RCU read-side
|
||||
* code.
|
||||
*/
|
||||
|
||||
#define rcu_assign_pointer(p, v) \
|
||||
({ \
|
||||
if (!__builtin_constant_p(v) || \
|
||||
((v) != NULL)) \
|
||||
smp_wmb(); \
|
||||
(p) = (v); \
|
||||
})
|
||||
__rcu_assign_pointer((p), (v), __rcu)
|
||||
|
||||
/**
|
||||
* RCU_INIT_POINTER() - initialize an RCU protected pointer
|
||||
*
|
||||
* Initialize an RCU-protected pointer in such a way to avoid RCU-lockdep
|
||||
* splats.
|
||||
*/
|
||||
#define RCU_INIT_POINTER(p, v) \
|
||||
p = (typeof(*v) __force __rcu *)(v)
|
||||
|
||||
/* Infrastructure to implement the synchronize_() primitives. */
|
||||
|
||||
|
|
@ -495,7 +602,7 @@ struct rcu_synchronize {
|
|||
extern void wakeme_after_rcu(struct rcu_head *head);
|
||||
|
||||
/**
|
||||
* call_rcu - Queue an RCU callback for invocation after a grace period.
|
||||
* call_rcu() - Queue an RCU callback for invocation after a grace period.
|
||||
* @head: structure to be used for queueing the RCU updates.
|
||||
* @func: actual update function to be invoked after the grace period
|
||||
*
|
||||
|
|
@ -509,7 +616,7 @@ extern void call_rcu(struct rcu_head *head,
|
|||
void (*func)(struct rcu_head *head));
|
||||
|
||||
/**
|
||||
* call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
|
||||
* call_rcu_bh() - Queue an RCU for invocation after a quicker grace period.
|
||||
* @head: structure to be used for queueing the RCU updates.
|
||||
* @func: actual update function to be invoked after the grace period
|
||||
*
|
||||
|
|
@ -566,37 +673,4 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
|
|||
}
|
||||
#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
|
||||
|
||||
#ifndef CONFIG_PROVE_RCU
|
||||
#define __do_rcu_dereference_check(c) do { } while (0)
|
||||
#endif /* #ifdef CONFIG_PROVE_RCU */
|
||||
|
||||
#define __rcu_dereference_index_check(p, c) \
|
||||
({ \
|
||||
typeof(p) _________p1 = ACCESS_ONCE(p); \
|
||||
__do_rcu_dereference_check(c); \
|
||||
smp_read_barrier_depends(); \
|
||||
(_________p1); \
|
||||
})
|
||||
|
||||
/**
|
||||
* rcu_dereference_index_check() - rcu_dereference for indices with debug checking
|
||||
* @p: The pointer to read, prior to dereferencing
|
||||
* @c: The conditions under which the dereference will take place
|
||||
*
|
||||
* Similar to rcu_dereference_check(), but omits the sparse checking.
|
||||
* This allows rcu_dereference_index_check() to be used on integers,
|
||||
* which can then be used as array indices. Attempting to use
|
||||
* rcu_dereference_check() on an integer will give compiler warnings
|
||||
* because the sparse address-space mechanism relies on dereferencing
|
||||
* the RCU-protected pointer. Dereferencing integers is not something
|
||||
* that even gcc will put up with.
|
||||
*
|
||||
* Note that this function does not implicitly check for RCU read-side
|
||||
* critical sections. If this function gains lots of uses, it might
|
||||
* make sense to provide versions for each flavor of RCU, but it does
|
||||
* not make sense as of early 2010.
|
||||
*/
|
||||
#define rcu_dereference_index_check(p, c) \
|
||||
__rcu_dereference_index_check((p), (c))
|
||||
|
||||
#endif /* __LINUX_RCUPDATE_H */
|
||||
|
|
|
|||
|
|
@ -108,12 +108,31 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp)
|
|||
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
||||
|
||||
/**
|
||||
* srcu_dereference - fetch SRCU-protected pointer with checking
|
||||
* srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
|
||||
* @p: the pointer to fetch and protect for later dereferencing
|
||||
* @sp: pointer to the srcu_struct, which is used to check that we
|
||||
* really are in an SRCU read-side critical section.
|
||||
* @c: condition to check for update-side use
|
||||
*
|
||||
* Makes rcu_dereference_check() do the dirty work.
|
||||
* If PROVE_RCU is enabled, invoking this outside of an RCU read-side
|
||||
* critical section will result in an RCU-lockdep splat, unless @c evaluates
|
||||
* to 1. The @c argument will normally be a logical expression containing
|
||||
* lockdep_is_held() calls.
|
||||
*/
|
||||
#define srcu_dereference(p, sp) \
|
||||
rcu_dereference_check(p, srcu_read_lock_held(sp))
|
||||
#define srcu_dereference_check(p, sp, c) \
|
||||
__rcu_dereference_check((p), srcu_read_lock_held(sp) || (c), __rcu)
|
||||
|
||||
/**
|
||||
* srcu_dereference - fetch SRCU-protected pointer for later dereferencing
|
||||
* @p: the pointer to fetch and protect for later dereferencing
|
||||
* @sp: pointer to the srcu_struct, which is used to check that we
|
||||
* really are in an SRCU read-side critical section.
|
||||
*
|
||||
* Makes rcu_dereference_check() do the dirty work. If PROVE_RCU
|
||||
* is enabled, invoking this outside of an RCU read-side critical
|
||||
* section will result in an RCU-lockdep splat.
|
||||
*/
|
||||
#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
|
||||
|
||||
/**
|
||||
* srcu_read_lock - register a new reader for an SRCU-protected structure.
|
||||
|
|
|
|||
|
|
@ -73,12 +73,14 @@ int debug_lockdep_rcu_enabled(void)
|
|||
EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
|
||||
|
||||
/**
|
||||
* rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
|
||||
* rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
|
||||
*
|
||||
* Check for bottom half being disabled, which covers both the
|
||||
* CONFIG_PROVE_RCU and not cases. Note that if someone uses
|
||||
* rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
|
||||
* will show the situation.
|
||||
* will show the situation. This is useful for debug checks in functions
|
||||
* that require that they be called within an RCU read-side critical
|
||||
* section.
|
||||
*
|
||||
* Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
|
||||
*/
|
||||
|
|
|
|||
|
|
@ -539,6 +539,19 @@ config PROVE_RCU_REPEATEDLY
|
|||
disabling, allowing multiple RCU-lockdep warnings to be printed
|
||||
on a single reboot.
|
||||
|
||||
config SPARSE_RCU_POINTER
|
||||
bool "RCU debugging: sparse-based checks for pointer usage"
|
||||
default n
|
||||
help
|
||||
This feature enables the __rcu sparse annotation for
|
||||
RCU-protected pointers. This annotation will cause sparse
|
||||
to flag any non-RCU used of annotated pointers. This can be
|
||||
helpful when debugging RCU usage. Please note that this feature
|
||||
is not intended to enforce code cleanliness; it is instead merely
|
||||
a debugging aid.
|
||||
|
||||
Say Y to make sparse flag questionable use of RCU-protected pointers
|
||||
|
||||
Say N if you are unsure.
|
||||
|
||||
config LOCKDEP
|
||||
|
|
|
|||
Loading…
Reference in a new issue