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| author | Bart Van Assche <bart.vanassche@wdc.com> | 2017-08-29 08:50:11 -0700 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2017-08-29 21:51:41 -0400 |
| commit | 26e3e3cb05604073f2e9969fb0f06f35eb3b3313 (patch) | |
| tree | fbdb1b52fa018e2dde35c9956aacfbd3636dfc1b /include/linux/rcupdate.h | |
| parent | fbf252335f8e2bd39d4ce59b1db0836a40ab227b (diff) | |
| download | lwn-26e3e3cb05604073f2e9969fb0f06f35eb3b3313.tar.gz lwn-26e3e3cb05604073f2e9969fb0f06f35eb3b3313.zip | |
scsi: rcu: Introduce rcu_swap_protected()
A common pattern in RCU code is to assign a new value to an RCU pointer
after having read and stored the old value. Introduce a macro for this
pattern.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.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>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'include/linux/rcupdate.h')
| -rw-r--r-- | include/linux/rcupdate.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index f816fc72b51e..8e920f0ecb07 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -408,6 +408,22 @@ static inline void rcu_preempt_sleep_check(void) { } }) /** + * rcu_swap_protected() - swap an RCU and a regular pointer + * @rcu_ptr: RCU pointer + * @ptr: regular pointer + * @c: the conditions under which the dereference will take place + * + * Perform swap(@rcu_ptr, @ptr) where @rcu_ptr is an RCU-annotated pointer and + * @c is the argument that is passed to the rcu_dereference_protected() call + * used to read that pointer. + */ +#define rcu_swap_protected(rcu_ptr, ptr, c) do { \ + typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c)); \ + rcu_assign_pointer((rcu_ptr), (ptr)); \ + (ptr) = __tmp; \ +} while (0) + +/** * rcu_access_pointer() - fetch RCU pointer with no dereferencing * @p: The pointer to read * |