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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-04-28 14:39:09 -0700 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-08-19 17:17:59 -0700 |
commit | ca5ecddfa8fcbd948c95530e7e817cee9fb43a3d (patch) | |
tree | 0ad1c320c2e6612a9a230a58d8588850701c048c /include/linux/srcu.h | |
parent | d34a16661ed0fed433c9469d7cfa3ca4d30ca42e (diff) | |
download | linux-stable-ca5ecddfa8fcbd948c95530e7e817cee9fb43a3d.tar.gz linux-stable-ca5ecddfa8fcbd948c95530e7e817cee9fb43a3d.tar.bz2 linux-stable-ca5ecddfa8fcbd948c95530e7e817cee9fb43a3d.zip |
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>
Diffstat (limited to 'include/linux/srcu.h')
-rw-r--r-- | include/linux/srcu.h | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 4d5d2f546dbf..6f456a720ff0 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.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. |