diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-generic/atomic64.h | 2 | ||||
| -rw-r--r-- | include/linux/atomic.h | 3 | ||||
| -rw-r--r-- | include/linux/completion.h | 45 | ||||
| -rw-r--r-- | include/linux/cpuset.h | 6 | ||||
| -rw-r--r-- | include/linux/futex.h | 7 | ||||
| -rw-r--r-- | include/linux/irqflags.h | 24 | ||||
| -rw-r--r-- | include/linux/jump_label.h | 33 | ||||
| -rw-r--r-- | include/linux/kasan-checks.h | 10 | ||||
| -rw-r--r-- | include/linux/lockdep.h | 161 | ||||
| -rw-r--r-- | include/linux/mm_types.h | 29 | ||||
| -rw-r--r-- | include/linux/rwsem-spinlock.h | 1 | ||||
| -rw-r--r-- | include/linux/rwsem.h | 1 | ||||
| -rw-r--r-- | include/linux/sched.h | 12 | ||||
| -rw-r--r-- | include/linux/sched/mm.h | 8 | ||||
| -rw-r--r-- | include/linux/spinlock.h | 41 |
15 files changed, 326 insertions, 57 deletions
diff --git a/include/asm-generic/atomic64.h b/include/asm-generic/atomic64.h index dad68bf46c77..8d28eb010d0d 100644 --- a/include/asm-generic/atomic64.h +++ b/include/asm-generic/atomic64.h @@ -21,6 +21,8 @@ typedef struct { extern long long atomic64_read(const atomic64_t *v); extern void atomic64_set(atomic64_t *v, long long i); +#define atomic64_set_release(v, i) atomic64_set((v), (i)) + #define ATOMIC64_OP(op) \ extern void atomic64_##op(long long a, atomic64_t *v); diff --git a/include/linux/atomic.h b/include/linux/atomic.h index c56be7410130..40d6bfec0e0d 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -38,6 +38,9 @@ * Besides, if an arch has a special barrier for acquire/release, it could * implement its own __atomic_op_* and use the same framework for building * variants + * + * If an architecture overrides __atomic_op_acquire() it will probably want + * to define smp_mb__after_spinlock(). */ #ifndef __atomic_op_acquire #define __atomic_op_acquire(op, args...) \ diff --git a/include/linux/completion.h b/include/linux/completion.h index 5d5aaae3af43..9bcebf509b4d 100644 --- a/include/linux/completion.h +++ b/include/linux/completion.h @@ -9,6 +9,9 @@ */ #include <linux/wait.h> +#ifdef CONFIG_LOCKDEP_COMPLETE +#include <linux/lockdep.h> +#endif /* * struct completion - structure used to maintain state for a "completion" @@ -25,10 +28,50 @@ struct completion { unsigned int done; wait_queue_head_t wait; +#ifdef CONFIG_LOCKDEP_COMPLETE + struct lockdep_map_cross map; +#endif }; +#ifdef CONFIG_LOCKDEP_COMPLETE +static inline void complete_acquire(struct completion *x) +{ + lock_acquire_exclusive((struct lockdep_map *)&x->map, 0, 0, NULL, _RET_IP_); +} + +static inline void complete_release(struct completion *x) +{ + lock_release((struct lockdep_map *)&x->map, 0, _RET_IP_); +} + +static inline void complete_release_commit(struct completion *x) +{ + lock_commit_crosslock((struct lockdep_map *)&x->map); +} + +#define init_completion(x) \ +do { \ + static struct lock_class_key __key; \ + lockdep_init_map_crosslock((struct lockdep_map *)&(x)->map, \ + "(complete)" #x, \ + &__key, 0); \ + __init_completion(x); \ +} while (0) +#else +#define init_completion(x) __init_completion(x) +static inline void complete_acquire(struct completion *x) {} +static inline void complete_release(struct completion *x) {} +static inline void complete_release_commit(struct completion *x) {} +#endif + +#ifdef CONFIG_LOCKDEP_COMPLETE +#define COMPLETION_INITIALIZER(work) \ + { 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait), \ + STATIC_CROSS_LOCKDEP_MAP_INIT("(complete)" #work, &(work)) } +#else #define COMPLETION_INITIALIZER(work) \ { 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) } +#endif #define COMPLETION_INITIALIZER_ONSTACK(work) \ ({ init_completion(&work); work; }) @@ -70,7 +113,7 @@ struct completion { * This inline function will initialize a dynamically created completion * structure. */ -static inline void init_completion(struct completion *x) +static inline void __init_completion(struct completion *x) { x->done = 0; init_waitqueue_head(&x->wait); diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 898cfe2eeb42..e74655d941b7 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -37,12 +37,6 @@ static inline bool cpusets_enabled(void) return static_branch_unlikely(&cpusets_enabled_key); } -static inline int nr_cpusets(void) -{ - /* jump label reference count + the top-level cpuset */ - return static_key_count(&cpusets_enabled_key.key) + 1; -} - static inline void cpuset_inc(void) { static_branch_inc(&cpusets_pre_enable_key); diff --git a/include/linux/futex.h b/include/linux/futex.h index 7c5b694864cd..f36bfd26f998 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -54,7 +54,6 @@ union futex_key { #ifdef CONFIG_FUTEX extern void exit_robust_list(struct task_struct *curr); -extern void exit_pi_state_list(struct task_struct *curr); #ifdef CONFIG_HAVE_FUTEX_CMPXCHG #define futex_cmpxchg_enabled 1 #else @@ -64,8 +63,14 @@ extern int futex_cmpxchg_enabled; static inline void exit_robust_list(struct task_struct *curr) { } +#endif + +#ifdef CONFIG_FUTEX_PI +extern void exit_pi_state_list(struct task_struct *curr); +#else static inline void exit_pi_state_list(struct task_struct *curr) { } #endif + #endif diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 5dd1272d1ab2..5fdd93bb9300 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -23,10 +23,26 @@ # define trace_softirq_context(p) ((p)->softirq_context) # define trace_hardirqs_enabled(p) ((p)->hardirqs_enabled) # define trace_softirqs_enabled(p) ((p)->softirqs_enabled) -# define trace_hardirq_enter() do { current->hardirq_context++; } while (0) -# define trace_hardirq_exit() do { current->hardirq_context--; } while (0) -# define lockdep_softirq_enter() do { current->softirq_context++; } while (0) -# define lockdep_softirq_exit() do { current->softirq_context--; } while (0) +# define trace_hardirq_enter() \ +do { \ + current->hardirq_context++; \ + crossrelease_hist_start(XHLOCK_HARD); \ +} while (0) +# define trace_hardirq_exit() \ +do { \ + current->hardirq_context--; \ + crossrelease_hist_end(XHLOCK_HARD); \ +} while (0) +# define lockdep_softirq_enter() \ +do { \ + current->softirq_context++; \ + crossrelease_hist_start(XHLOCK_SOFT); \ +} while (0) +# define lockdep_softirq_exit() \ +do { \ + current->softirq_context--; \ + crossrelease_hist_end(XHLOCK_SOFT); \ +} while (0) # define INIT_TRACE_IRQFLAGS .softirqs_enabled = 1, #else # define trace_hardirqs_on() do { } while (0) diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index 2afd74b9d844..cd5861651b17 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -163,6 +163,8 @@ extern void jump_label_apply_nops(struct module *mod); extern int static_key_count(struct static_key *key); extern void static_key_enable(struct static_key *key); extern void static_key_disable(struct static_key *key); +extern void static_key_enable_cpuslocked(struct static_key *key); +extern void static_key_disable_cpuslocked(struct static_key *key); /* * We should be using ATOMIC_INIT() for initializing .enabled, but @@ -234,24 +236,29 @@ static inline int jump_label_apply_nops(struct module *mod) static inline void static_key_enable(struct static_key *key) { - int count = static_key_count(key); - - WARN_ON_ONCE(count < 0 || count > 1); + STATIC_KEY_CHECK_USE(); - if (!count) - static_key_slow_inc(key); + if (atomic_read(&key->enabled) != 0) { + WARN_ON_ONCE(atomic_read(&key->enabled) != 1); + return; + } + atomic_set(&key->enabled, 1); } static inline void static_key_disable(struct static_key *key) { - int count = static_key_count(key); - - WARN_ON_ONCE(count < 0 || count > 1); + STATIC_KEY_CHECK_USE(); - if (count) - static_key_slow_dec(key); + if (atomic_read(&key->enabled) != 1) { + WARN_ON_ONCE(atomic_read(&key->enabled) != 0); + return; + } + atomic_set(&key->enabled, 0); } +#define static_key_enable_cpuslocked(k) static_key_enable((k)) +#define static_key_disable_cpuslocked(k) static_key_disable((k)) + #define STATIC_KEY_INIT_TRUE { .enabled = ATOMIC_INIT(1) } #define STATIC_KEY_INIT_FALSE { .enabled = ATOMIC_INIT(0) } @@ -413,8 +420,10 @@ extern bool ____wrong_branch_error(void); * Normal usage; boolean enable/disable. */ -#define static_branch_enable(x) static_key_enable(&(x)->key) -#define static_branch_disable(x) static_key_disable(&(x)->key) +#define static_branch_enable(x) static_key_enable(&(x)->key) +#define static_branch_disable(x) static_key_disable(&(x)->key) +#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key) +#define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key) #endif /* __ASSEMBLY__ */ diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h index b7f8aced7870..41960fecf783 100644 --- a/include/linux/kasan-checks.h +++ b/include/linux/kasan-checks.h @@ -2,11 +2,13 @@ #define _LINUX_KASAN_CHECKS_H #ifdef CONFIG_KASAN -void kasan_check_read(const void *p, unsigned int size); -void kasan_check_write(const void *p, unsigned int size); +void kasan_check_read(const volatile void *p, unsigned int size); +void kasan_check_write(const volatile void *p, unsigned int size); #else -static inline void kasan_check_read(const void *p, unsigned int size) { } -static inline void kasan_check_write(const void *p, unsigned int size) { } +static inline void kasan_check_read(const volatile void *p, unsigned int size) +{ } +static inline void kasan_check_write(const volatile void *p, unsigned int size) +{ } #endif #endif diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index fffe49f188e6..651cc61af041 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -29,7 +29,7 @@ extern int lock_stat; * We'd rather not expose kernel/lockdep_states.h this wide, but we do need * the total number of states... :-( */ -#define XXX_LOCK_USAGE_STATES (1+3*4) +#define XXX_LOCK_USAGE_STATES (1+2*4) /* * NR_LOCKDEP_CACHING_CLASSES ... Number of classes @@ -155,6 +155,12 @@ struct lockdep_map { int cpu; unsigned long ip; #endif +#ifdef CONFIG_LOCKDEP_CROSSRELEASE + /* + * Whether it's a crosslock. + */ + int cross; +#endif }; static inline void lockdep_copy_map(struct lockdep_map *to, @@ -258,8 +264,95 @@ struct held_lock { unsigned int hardirqs_off:1; unsigned int references:12; /* 32 bits */ unsigned int pin_count; +#ifdef CONFIG_LOCKDEP_CROSSRELEASE + /* + * Generation id. + * + * A value of cross_gen_id will be stored when holding this, + * which is globally increased whenever each crosslock is held. + */ + unsigned int gen_id; +#endif +}; + +#ifdef CONFIG_LOCKDEP_CROSSRELEASE +#define MAX_XHLOCK_TRACE_ENTRIES 5 + +/* + * This is for keeping locks waiting for commit so that true dependencies + * can be added at commit step. + */ +struct hist_lock { + /* + * Id for each entry in the ring buffer. This is used to + * decide whether the ring buffer was overwritten or not. + * + * For example, + * + * |<----------- hist_lock ring buffer size ------->| + * pppppppppppppppppppppiiiiiiiiiiiiiiiiiiiiiiiiiiiii + * wrapped > iiiiiiiiiiiiiiiiiiiiiiiiiii....................... + * + * where 'p' represents an acquisition in process + * context, 'i' represents an acquisition in irq + * context. + * + * In this example, the ring buffer was overwritten by + * acquisitions in irq context, that should be detected on + * rollback or commit. + */ + unsigned int hist_id; + + /* + * Seperate stack_trace data. This will be used at commit step. + */ + struct stack_trace trace; + unsigned long trace_entries[MAX_XHLOCK_TRACE_ENTRIES]; + + /* + * Seperate hlock instance. This will be used at commit step. + * + * TODO: Use a smaller data structure containing only necessary + * data. However, we should make lockdep code able to handle the + * smaller one first. + */ + struct held_lock hlock; +}; + +/* + * To initialize a lock as crosslock, lockdep_init_map_crosslock() should + * be called instead of lockdep_init_map(). + */ +struct cross_lock { + /* + * When more than one acquisition of crosslocks are overlapped, + * we have to perform commit for them based on cross_gen_id of + * the first acquisition, which allows us to add more true + * dependencies. + * + * Moreover, when no acquisition of a crosslock is in progress, + * we should not perform commit because the lock might not exist + * any more, which might cause incorrect memory access. So we + * have to track the number of acquisitions of a crosslock. + */ + int nr_acquire; + + /* + * Seperate hlock instance. This will be used at commit step. + * + * TODO: Use a smaller data structure containing only necessary + * data. However, we should make lockdep code able to handle the + * smaller one first. + */ + struct held_lock hlock; }; +struct lockdep_map_cross { + struct lockdep_map map; + struct cross_lock xlock; +}; +#endif + /* * Initialization, self-test and debugging-output methods: */ @@ -282,13 +375,6 @@ extern void lockdep_init_map(struct lockdep_map *lock, const char *name, struct lock_class_key *key, int subclass); /* - * To initialize a lockdep_map statically use this macro. - * Note that _name must not be NULL. - */ -#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \ - { .name = (_name), .key = (void *)(_key), } - -/* * Reinitialize a lock key - for cases where there is special locking or * special initialization of locks so that the validator gets the scope * of dependencies wrong: they are either too broad (they need a class-split) @@ -363,10 +449,6 @@ static inline void lock_set_subclass(struct lockdep_map *lock, extern void lock_downgrade(struct lockdep_map *lock, unsigned long ip); -extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask); -extern void lockdep_clear_current_reclaim_state(void); -extern void lockdep_trace_alloc(gfp_t mask); - struct pin_cookie { unsigned int val; }; #define NIL_COOKIE (struct pin_cookie){ .val = 0U, } @@ -375,7 +457,7 @@ extern struct pin_cookie lock_pin_lock(struct lockdep_map *lock); extern void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie); extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie); -# define INIT_LOCKDEP .lockdep_recursion = 0, .lockdep_reclaim_gfp = 0, +# define INIT_LOCKDEP .lockdep_recursion = 0, #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0) @@ -416,9 +498,6 @@ static inline void lockdep_on(void) # define lock_downgrade(l, i) do { } while (0) # define lock_set_class(l, n, k, s, i) do { } while (0) # define lock_set_subclass(l, s, i) do { } while (0) -# define lockdep_set_current_reclaim_state(g) do { } while (0) -# define lockdep_clear_current_reclaim_state() do { } while (0) -# define lockdep_trace_alloc(g) do { } while (0) # define lockdep_info() do { } while (0) # define lockdep_init_map(lock, name, key, sub) \ do { (void)(name); (void)(key); } while (0) @@ -467,6 +546,56 @@ struct pin_cookie { }; #endif /* !LOCKDEP */ +enum xhlock_context_t { + XHLOCK_HARD, + XHLOCK_SOFT, + XHLOCK_PROC, + XHLOCK_CTX_NR, +}; + +#ifdef CONFIG_LOCKDEP_CROSSRELEASE +extern void lockdep_init_map_crosslock(struct lockdep_map *lock, + const char *name, + struct lock_class_key *key, + int subclass); +extern void lock_commit_crosslock(struct lockdep_map *lock); + +/* + * What we essencially have to initialize is 'nr_acquire'. Other members + * will be initialized in add_xlock(). + */ +#define STATIC_CROSS_LOCK_INIT() \ + { .nr_acquire = 0,} + +#define STATIC_CROSS_LOCKDEP_MAP_INIT(_name, _key) \ + { .map.name = (_name), .map.key = (void *)(_key), \ + .map.cross = 1, .xlock = STATIC_CROSS_LOCK_INIT(), } + +/* + * To initialize a lockdep_map statically use this macro. + * Note that _name must not be NULL. + */ +#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \ + { .name = (_name), .key = (void *)(_key), .cross = 0, } + +extern void crossrelease_hist_start(enum xhlock_context_t c); +extern void crossrelease_hist_end(enum xhlock_context_t c); +extern void lockdep_init_task(struct task_struct *task); +extern void lockdep_free_task(struct task_struct *task); +#else +/* + * To initialize a lockdep_map statically use this macro. + * Note that _name must not be NULL. + */ +#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \ + { .name = (_name), .key = (void *)(_key), } + +static inline void crossrelease_hist_start(enum xhlock_context_t c) {} +static inline void crossrelease_hist_end(enum xhlock_context_t c) {} +static inline void lockdep_init_task(struct task_struct *task) {} +static inline void lockdep_free_task(struct task_struct *task) {} +#endif + #ifdef CONFIG_LOCK_STAT extern void lock_contended(struct lockdep_map *lock, unsigned long ip); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3cadee0a3508..dc1edec05a3f 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -535,6 +535,10 @@ extern void tlb_finish_mmu(struct mmu_gather *tlb, */ static inline bool mm_tlb_flush_pending(struct mm_struct *mm) { + /* + * Must be called with PTL held; such that our PTL acquire will have + * observed the store from set_tlb_flush_pending(). + */ return atomic_read(&mm->tlb_flush_pending) > 0; } @@ -556,10 +560,29 @@ static inline void inc_tlb_flush_pending(struct mm_struct *mm) atomic_inc(&mm->tlb_flush_pending); /* - * Guarantee that the tlb_flush_pending increase does not leak into the - * critical section updating the page tables + * The only time this value is relevant is when there are indeed pages + * to flush. And we'll only flush pages after changing them, which + * requires the PTL. + * + * So the ordering here is: + * + * atomic_inc(&mm->tlb_flush_pending); + * spin_lock(&ptl); + * ... + * set_pte_at(); + * spin_unlock(&ptl); + * + * spin_lock(&ptl) + * mm_tlb_flush_pending(); + * .... + * spin_unlock(&ptl); + * + * flush_tlb_range(); + * atomic_dec(&mm->tlb_flush_pending); + * + * So the =true store is constrained by the PTL unlock, and the =false + * store is constrained by the TLB invalidate. */ - smp_mb__before_spinlock(); } /* Clearing is done after a TLB flush, which also provides a barrier. */ diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h index ae0528b834cd..e784761a4443 100644 --- a/include/linux/rwsem-spinlock.h +++ b/include/linux/rwsem-spinlock.h @@ -32,6 +32,7 @@ struct rw_semaphore { #define RWSEM_UNLOCKED_VALUE 0x00000000 extern void __down_read(struct rw_semaphore *sem); +extern int __must_check __down_read_killable(struct rw_semaphore *sem); extern int __down_read_trylock(struct rw_semaphore *sem); extern void __down_write(struct rw_semaphore *sem); extern int __must_check __down_write_killable(struct rw_semaphore *sem); diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h index dd1d14250340..0ad7318ff299 100644 --- a/include/linux/rwsem.h +++ b/include/linux/rwsem.h @@ -44,6 +44,7 @@ struct rw_semaphore { }; extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem); +extern struct rw_semaphore *rwsem_down_read_failed_killable(struct rw_semaphore *sem); extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem); extern struct rw_semaphore *rwsem_down_write_failed_killable(struct rw_semaphore *sem); extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *); diff --git a/include/linux/sched.h b/include/linux/sched.h index 8337e2db0bb2..772c5f643764 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -846,7 +846,17 @@ struct task_struct { int lockdep_depth; unsigned int lockdep_recursion; struct held_lock held_locks[MAX_LOCK_DEPTH]; - gfp_t lockdep_reclaim_gfp; +#endif + +#ifdef CONFIG_LOCKDEP_CROSSRELEASE +#define MAX_XHLOCKS_NR 64UL + struct hist_lock *xhlocks; /* Crossrelease history locks */ + unsigned int xhlock_idx; + /* For restoring at history boundaries */ + unsigned int xhlock_idx_hist[XHLOCK_CTX_NR]; + unsigned int hist_id; + /* For overwrite check at each context exit */ + unsigned int hist_id_save[XHLOCK_CTX_NR]; #endif #ifdef CONFIG_UBSAN diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 2b24a6974847..2b0a281f9d26 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -167,6 +167,14 @@ static inline gfp_t current_gfp_context(gfp_t flags) return flags; } +#ifdef CONFIG_LOCKDEP +extern void fs_reclaim_acquire(gfp_t gfp_mask); +extern void fs_reclaim_release(gfp_t gfp_mask); +#else +static inline void fs_reclaim_acquire(gfp_t gfp_mask) { } +static inline void fs_reclaim_release(gfp_t gfp_mask) { } +#endif + static inline unsigned int memalloc_noio_save(void) { unsigned int flags = current->flags & PF_MEMALLOC_NOIO; diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index d9510e8522d4..4e8cce19b507 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -118,16 +118,39 @@ do { \ #endif /* - * Despite its name it doesn't necessarily has to be a full barrier. - * It should only guarantee that a STORE before the critical section - * can not be reordered with LOADs and STOREs inside this section. - * spin_lock() is the one-way barrier, this LOAD can not escape out - * of the region. So the default implementation simply ensures that - * a STORE can not move into the critical section, smp_wmb() should - * serialize it with another STORE done by spin_lock(). + * This barrier must provide two things: + * + * - it must guarantee a STORE before the spin_lock() is ordered against a + * LOAD after it, see the comments at its two usage sites. + * + * - it must ensure the critical section is RCsc. + * + * The latter is important for cases where we observe values written by other + * CPUs in spin-loops, without barriers, while being subject to scheduling. + * + * CPU0 CPU1 CPU2 + * + * for (;;) { + * if (READ_ONCE(X)) + * break; + * } + * X=1 + * <sched-out> + * <sched-in> + * r = X; + * + * without transitivity it could be that CPU1 observes X!=0 breaks the loop, + * we get migrated and CPU2 sees X==0. + * + * Since most load-store architectures implement ACQUIRE with an smp_mb() after + * the LL/SC loop, they need no further barriers. Similarly all our TSO + * architectures imply an smp_mb() for each atomic instruction and equally don't + * need more. + * + * Architectures that can implement ACQUIRE better need to take care. */ -#ifndef smp_mb__before_spinlock -#define smp_mb__before_spinlock() smp_wmb() +#ifndef smp_mb__after_spinlock +#define smp_mb__after_spinlock() do { } while (0) #endif /** |