diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2019-09-23 15:05:11 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-06-28 10:15:28 +0200 |
| commit | deb5c34ee45d493bfdd42fa3fb98e21435f2530d (patch) | |
| tree | 661e2242981ef8fd6c2fa55e1e9fdf90a339e4ff /include/linux | |
| parent | d45de50cd11dca1a30c04945dea7e09586b1838f (diff) | |
rcu: Upgrade rcu_swap_protected() to rcu_replace_pointer()
[ Upstream commit a63fc6b75cca984c71f095282e0227a390ba88f3 ]
Although the rcu_swap_protected() macro follows the example of
swap(), the interactions with RCU make its update of its argument
somewhat counter-intuitive. This commit therefore introduces
an rcu_replace_pointer() that returns the old value of the RCU
pointer instead of doing the argument update. Once all the uses of
rcu_swap_protected() are updated to instead use rcu_replace_pointer(),
rcu_swap_protected() will be removed.
Link: https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4gg6Hw@mail.gmail.com/
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
[ paulmck: From rcu_replace() to rcu_replace_pointer() per Ingo Molnar. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Shane M Seymour <shane.seymour@hpe.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Stable-dep-of: a61675294735 ("ieee802154: hwsim: Fix possible memory leaks")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/rcupdate.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 68cbe111420b..cf139d6e5c1d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -411,6 +411,24 @@ static inline void rcu_preempt_sleep_check(void) { } }) /** + * rcu_replace_pointer() - replace an RCU pointer, returning its old value + * @rcu_ptr: RCU pointer, whose old value is returned + * @ptr: regular pointer + * @c: the lockdep conditions under which the dereference will take place + * + * Perform a replacement, where @rcu_ptr is an RCU-annotated + * pointer and @c is the lockdep argument that is passed to the + * rcu_dereference_protected() call used to read that pointer. The old + * value of @rcu_ptr is returned, and @rcu_ptr is set to @ptr. + */ +#define rcu_replace_pointer(rcu_ptr, ptr, c) \ +({ \ + typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c)); \ + rcu_assign_pointer((rcu_ptr), (ptr)); \ + __tmp; \ +}) + +/** * rcu_swap_protected() - swap an RCU and a regular pointer * @rcu_ptr: RCU pointer * @ptr: regular pointer |