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rcu: Mark __rcu_access_pointer() as context_unsafe()

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A simple comparison of a pointer returned by rcu_access_pointer() results
in a context-analysis warning for lockless inspection of the RCU-protected
(also known as __rcu-protected) pointer.  This can be suppressed by
placing context_unsafe() calls around calls rcu_access_pointer(),
but this is messy and distracting.  This commit therefore wraps the
underlying __rcu_access_pointer() macro with a call to context_unsafe(),
thereby informing the context-analysis code that rcu_access_pointer()
may safely be invoked outside of an RCU read-side critical section.

Reported-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Marco Elver <elver@google.com>
This commit is contained in:
Paul E. McKenney 2026-06-28 09:00:01 -07:00
parent 1384ea908e
commit 573d76f7db
1 changed files with 2 additions and 2 deletions
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4
include/linux/rcupdate.h
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@ -490,12 +490,12 @@ context_unsafe( \
*/
#define unrcu_pointer(p) __unrcu_pointer(p, __UNIQUE_ID(rcu))
#define __rcu_access_pointer(p, local, space) \
#define __rcu_access_pointer(p, local, space) context_unsafe( \
({ \
typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
rcu_check_sparse(p, space); \
((typeof(*p) __force __kernel *)(local)); \
})
}) )
#define __rcu_dereference_check(p, local, c, space) \
({ \
/* Dependency order vs. p above. */ \