From 3297481d688a5cc2973ea58bd78e66b8639748b1 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 26 Oct 2021 12:03:48 +0200 Subject: futex: Remove futex_cmpxchg detection Now that all architectures have a working futex implementation in any configuration, remove the runtime detection code. Signed-off-by: Arnd Bergmann Signed-off-by: Thomas Gleixner Reviewed-by: Russell King (Oracle) Acked-by: Vineet Gupta Acked-by: Max Filippov Acked-by: Christian Borntraeger Link: https://lore.kernel.org/r/20211026100432.1730393-2-arnd@kernel.org --- kernel/futex/core.c | 35 ----------------------------------- 1 file changed, 35 deletions(-) (limited to 'kernel/futex/core.c') diff --git a/kernel/futex/core.c b/kernel/futex/core.c index 25d8a88b32e5..926c2bb752bc 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -41,11 +41,6 @@ #include "futex.h" #include "../locking/rtmutex_common.h" -#ifndef CONFIG_HAVE_FUTEX_CMPXCHG -int __read_mostly futex_cmpxchg_enabled; -#endif - - /* * The base of the bucket array and its size are always used together * (after initialization only in futex_hash()), so ensure that they @@ -776,9 +771,6 @@ static void exit_robust_list(struct task_struct *curr) unsigned long futex_offset; int rc; - if (!futex_cmpxchg_enabled) - return; - /* * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): @@ -874,9 +866,6 @@ static void compat_exit_robust_list(struct task_struct *curr) compat_long_t futex_offset; int rc; - if (!futex_cmpxchg_enabled) - return; - /* * Fetch the list head (which was registered earlier, via * sys_set_robust_list()): @@ -950,8 +939,6 @@ static void exit_pi_state_list(struct task_struct *curr) struct futex_hash_bucket *hb; union futex_key key = FUTEX_KEY_INIT; - if (!futex_cmpxchg_enabled) - return; /* * We are a ZOMBIE and nobody can enqueue itself on * pi_state_list anymore, but we have to be careful @@ -1125,26 +1112,6 @@ void futex_exit_release(struct task_struct *tsk) futex_cleanup_end(tsk, FUTEX_STATE_DEAD); } -static void __init futex_detect_cmpxchg(void) -{ -#ifndef CONFIG_HAVE_FUTEX_CMPXCHG - u32 curval; - - /* - * This will fail and we want it. Some arch implementations do - * runtime detection of the futex_atomic_cmpxchg_inatomic() - * functionality. We want to know that before we call in any - * of the complex code paths. Also we want to prevent - * registration of robust lists in that case. NULL is - * guaranteed to fault and we get -EFAULT on functional - * implementation, the non-functional ones will return - * -ENOSYS. - */ - if (futex_cmpxchg_value_locked(&curval, NULL, 0, 0) == -EFAULT) - futex_cmpxchg_enabled = 1; -#endif -} - static int __init futex_init(void) { unsigned int futex_shift; @@ -1163,8 +1130,6 @@ static int __init futex_init(void) futex_hashsize, futex_hashsize); futex_hashsize = 1UL << futex_shift; - futex_detect_cmpxchg(); - for (i = 0; i < futex_hashsize; i++) { atomic_set(&futex_queues[i].waiters, 0); plist_head_init(&futex_queues[i].chain); -- cgit v1.2.3-59-g8ed1b