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Diffstat (limited to 'Documentation/RCU/lockdep.rst')
| -rw-r--r-- | Documentation/RCU/lockdep.rst | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/Documentation/RCU/lockdep.rst b/Documentation/RCU/lockdep.rst index 9308f1bdba05..741b157bbacb 100644 --- a/Documentation/RCU/lockdep.rst +++ b/Documentation/RCU/lockdep.rst @@ -65,13 +65,12 @@ checking of rcu_dereference() primitives: rcu_access_pointer(p): Return the value of the pointer and omit all barriers, but retain the compiler constraints that prevent duplicating - or coalescsing. This is useful when testing the + or coalescing. This is useful when testing the value of the pointer itself, for example, against NULL. The rcu_dereference_check() check expression can be any boolean -expression, but would normally include a lockdep expression. However, -any boolean expression can be used. For a moderately ornate example, -consider the following:: +expression, but would normally include a lockdep expression. For a +moderately ornate example, consider the following:: file = rcu_dereference_check(fdt->fd[fd], lockdep_is_held(&files->file_lock) || @@ -97,17 +96,17 @@ code, it could instead be written as follows:: atomic_read(&files->count) == 1); This would verify cases #2 and #3 above, and furthermore lockdep would -complain if this was used in an RCU read-side critical section unless one -of these two cases held. Because rcu_dereference_protected() omits all -barriers and compiler constraints, it generates better code than do the -other flavors of rcu_dereference(). On the other hand, it is illegal +complain even if this was used in an RCU read-side critical section unless +one of these two cases held. Because rcu_dereference_protected() omits +all barriers and compiler constraints, it generates better code than do +the other flavors of rcu_dereference(). On the other hand, it is illegal to use rcu_dereference_protected() if either the RCU-protected pointer or the RCU-protected data that it points to can change concurrently. Like rcu_dereference(), when lockdep is enabled, RCU list and hlist traversal primitives check for being called from within an RCU read-side critical section. However, a lockdep expression can be passed to them -as a additional optional argument. With this lockdep expression, these +as an additional optional argument. With this lockdep expression, these traversal primitives will complain only if the lockdep expression is false and they are called from outside any RCU read-side critical section. |