From: Peter Zijlstra <pet...@infradead.org> I want to use lockless_dereference() from seqlock.h, which would mean including rcupdate.h from it, however rcupdate.h already includes seqlock.h.
Avoid this by moving lockless_dereference() into compiler.h. This is somewhat tricky since it uses smp_read_barrier_depends() which isn't available there, but its a CPP macro so we can get away with it. The alternative would be moving it into asm/barrier.h, but that would be updating each arch (I can do if people feel that is more appropriate). Cc: Paul McKenney <paul...@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Signed-off-by: Rusty Russell <ru...@rustcorp.com.au> https://jira.sw.ru/browse/PSBM-69081 (cherry picked from commit 0a04b0166929405cd833c1cc40f99e862b965ddc) Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> --- include/linux/compiler.h | 15 +++++++++++++++ include/linux/rcupdate.h | 15 --------------- 2 files changed, 15 insertions(+), 15 deletions(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 73647b4cd947..7ce904c040dd 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -466,6 +466,21 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s */ #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) +/** + * lockless_dereference() - safely load a pointer for later dereference + * @p: The pointer to load + * + * Similar to rcu_dereference(), but for situations where the pointed-to + * object's lifetime is managed by something other than RCU. That + * "something other" might be reference counting or simple immortality. + */ +#define lockless_dereference(p) \ +({ \ + typeof(p) _________p1 = ACCESS_ONCE(p); \ + smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ + (_________p1); \ +}) + /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ #ifdef CONFIG_KPROBES # define __kprobes __attribute__((__section__(".kprobes.text"))) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 68df10240cb4..981261775a41 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -580,21 +580,6 @@ static inline void rcu_preempt_sleep_check(void) } while (0) /** - * lockless_dereference() - safely load a pointer for later dereference - * @p: The pointer to load - * - * Similar to rcu_dereference(), but for situations where the pointed-to - * object's lifetime is managed by something other than RCU. That - * "something other" might be reference counting or simple immortality. - */ -#define lockless_dereference(p) \ -({ \ - typeof(p) _________p1 = ACCESS_ONCE(p); \ - smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ - (_________p1); \ -}) - -/** * rcu_access_pointer() - fetch RCU pointer with no dereferencing * @p: The pointer to read * -- 2.13.5 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
