From: Sebastian Andrzej Siewior Date: Tue, 26 Feb 2019 16:56:02 +0100 Subject: [PATCH 139/353] rbtree: don't include the rcu header MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=692b6f51268cd63d3c6eba42d2d8c3689b084b17 The RCU header pulls in spinlock.h and fails due not yet defined types: |In file included from include/linux/spinlock.h:275:0, | from include/linux/rcupdate.h:38, | from include/linux/rbtree.h:34, | from include/linux/rtmutex.h:17, | from include/linux/spinlock_types.h:18, | from kernel/bounds.c:13: |include/linux/rwlock_rt.h:16:38: error: unknown type name ‘rwlock_t’ | extern void __lockfunc rt_write_lock(rwlock_t *rwlock); | ^ This patch moves the required RCU function from the rcupdate.h header file into a new header file which can be included by both users. Signed-off-by: Sebastian Andrzej Siewior --- include/linux/rbtree.h | 2 +- include/linux/rcu_assign_pointer.h | 54 ++++++++++++++++++++++++++++++ include/linux/rcupdate.h | 49 +-------------------------- 3 files changed, 56 insertions(+), 49 deletions(-) create mode 100644 include/linux/rcu_assign_pointer.h diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h index fcbeed4053ef..2aa2aec354c2 100644 --- a/include/linux/rbtree.h +++ b/include/linux/rbtree.h @@ -31,7 +31,7 @@ #include #include -#include +#include struct rb_node { unsigned long __rb_parent_color; diff --git a/include/linux/rcu_assign_pointer.h b/include/linux/rcu_assign_pointer.h new file mode 100644 index 000000000000..7066962a4379 --- /dev/null +++ b/include/linux/rcu_assign_pointer.h @@ -0,0 +1,54 @@ +#ifndef __LINUX_RCU_ASSIGN_POINTER_H__ +#define __LINUX_RCU_ASSIGN_POINTER_H__ +#include +#include + +/** + * RCU_INITIALIZER() - statically initialize an RCU-protected global variable + * @v: The value to statically initialize with. + */ +#define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v) + +/** + * rcu_assign_pointer() - assign to RCU-protected pointer + * @p: pointer to assign to + * @v: value to assign (publish) + * + * Assigns the specified value to the specified RCU-protected + * pointer, ensuring that any concurrent RCU readers will see + * any prior initialization. + * + * Inserts memory barriers on architectures that require them + * (which is most of them), and also prevents the compiler from + * reordering the code that initializes the structure after the pointer + * assignment. More importantly, this call documents which pointers + * will be dereferenced by RCU read-side code. + * + * In some special cases, you may use RCU_INIT_POINTER() instead + * of rcu_assign_pointer(). RCU_INIT_POINTER() is a bit faster due + * to the fact that it does not constrain either the CPU or the compiler. + * That said, using RCU_INIT_POINTER() when you should have used + * rcu_assign_pointer() is a very bad thing that results in + * impossible-to-diagnose memory corruption. So please be careful. + * See the RCU_INIT_POINTER() comment header for details. + * + * Note that rcu_assign_pointer() evaluates each of its arguments only + * once, appearances notwithstanding. One of the "extra" evaluations + * is in typeof() and the other visible only to sparse (__CHECKER__), + * neither of which actually execute the argument. As with most cpp + * macros, this execute-arguments-only-once property is important, so + * please be careful when making changes to rcu_assign_pointer() and the + * other macros that it invokes. + */ +#define rcu_assign_pointer(p, v) \ +({ \ + uintptr_t _r_a_p__v = (uintptr_t)(v); \ + \ + if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \ + WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \ + else \ + smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \ + _r_a_p__v; \ +}) + +#endif diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 027c58cdbb6e..e6733d7911e9 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -42,6 +42,7 @@ #include #include #include +#include #define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b)) #define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b)) @@ -369,54 +370,6 @@ static inline void rcu_preempt_sleep_check(void) { } ((typeof(*p) __force __kernel *)(________p1)); \ }) -/** - * RCU_INITIALIZER() - statically initialize an RCU-protected global variable - * @v: The value to statically initialize with. - */ -#define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v) - -/** - * rcu_assign_pointer() - assign to RCU-protected pointer - * @p: pointer to assign to - * @v: value to assign (publish) - * - * Assigns the specified value to the specified RCU-protected - * pointer, ensuring that any concurrent RCU readers will see - * any prior initialization. - * - * Inserts memory barriers on architectures that require them - * (which is most of them), and also prevents the compiler from - * reordering the code that initializes the structure after the pointer - * assignment. More importantly, this call documents which pointers - * will be dereferenced by RCU read-side code. - * - * In some special cases, you may use RCU_INIT_POINTER() instead - * of rcu_assign_pointer(). RCU_INIT_POINTER() is a bit faster due - * to the fact that it does not constrain either the CPU or the compiler. - * That said, using RCU_INIT_POINTER() when you should have used - * rcu_assign_pointer() is a very bad thing that results in - * impossible-to-diagnose memory corruption. So please be careful. - * See the RCU_INIT_POINTER() comment header for details. - * - * Note that rcu_assign_pointer() evaluates each of its arguments only - * once, appearances notwithstanding. One of the "extra" evaluations - * is in typeof() and the other visible only to sparse (__CHECKER__), - * neither of which actually execute the argument. As with most cpp - * macros, this execute-arguments-only-once property is important, so - * please be careful when making changes to rcu_assign_pointer() and the - * other macros that it invokes. - */ -#define rcu_assign_pointer(p, v) \ -({ \ - uintptr_t _r_a_p__v = (uintptr_t)(v); \ - \ - if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \ - WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \ - else \ - smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \ - _r_a_p__v; \ -}) - /** * rcu_swap_protected() - swap an RCU and a regular pointer * @rcu_ptr: RCU pointer