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authorArnd Bergmann <arnd@arndb.de>2021-10-26 12:03:48 +0200
committerThomas Gleixner <tglx@linutronix.de>2021-11-25 00:02:28 +0100
commit3297481d688a5cc2973ea58bd78e66b8639748b1 (patch)
tree3f9e7d8fb1601489125df8c689a28d3e29c8ef63 /kernel/futex
parent3f2bedabb62c6210df63b604dc988d2f7f56f947 (diff)
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 <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Acked-by: Vineet Gupta <vgupta@kernel.org> Acked-by: Max Filippov <jcmvbkbc@gmail.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Link: https://lore.kernel.org/r/20211026100432.1730393-2-arnd@kernel.org
Diffstat (limited to 'kernel/futex')
-rw-r--r--kernel/futex/core.c35
-rw-r--r--kernel/futex/futex.h6
-rw-r--r--kernel/futex/syscalls.c22
3 files changed, 0 insertions, 63 deletions
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);
diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h
index 040ae4277cb0..c264cbeab71c 100644
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -27,12 +27,6 @@
#define FLAGS_CLOCKRT 0x02
#define FLAGS_HAS_TIMEOUT 0x04
-#ifdef CONFIG_HAVE_FUTEX_CMPXCHG
-#define futex_cmpxchg_enabled 1
-#else
-extern int __read_mostly futex_cmpxchg_enabled;
-#endif
-
#ifdef CONFIG_FAIL_FUTEX
extern bool should_fail_futex(bool fshared);
#else
diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c
index 6f91a07a6a83..086a22d1adb7 100644
--- a/kernel/futex/syscalls.c
+++ b/kernel/futex/syscalls.c
@@ -29,8 +29,6 @@
SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
size_t, len)
{
- if (!futex_cmpxchg_enabled)
- return -ENOSYS;
/*
* The kernel knows only one size for now:
*/
@@ -56,9 +54,6 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
unsigned long ret;
struct task_struct *p;
- if (!futex_cmpxchg_enabled)
- return -ENOSYS;
-
rcu_read_lock();
ret = -ESRCH;
@@ -104,17 +99,6 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
}
switch (cmd) {
- case FUTEX_LOCK_PI:
- case FUTEX_LOCK_PI2:
- case FUTEX_UNLOCK_PI:
- case FUTEX_TRYLOCK_PI:
- case FUTEX_WAIT_REQUEUE_PI:
- case FUTEX_CMP_REQUEUE_PI:
- if (!futex_cmpxchg_enabled)
- return -ENOSYS;
- }
-
- switch (cmd) {
case FUTEX_WAIT:
val3 = FUTEX_BITSET_MATCH_ANY;
fallthrough;
@@ -323,9 +307,6 @@ COMPAT_SYSCALL_DEFINE2(set_robust_list,
struct compat_robust_list_head __user *, head,
compat_size_t, len)
{
- if (!futex_cmpxchg_enabled)
- return -ENOSYS;
-
if (unlikely(len != sizeof(*head)))
return -EINVAL;
@@ -342,9 +323,6 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
unsigned long ret;
struct task_struct *p;
- if (!futex_cmpxchg_enabled)
- return -ENOSYS;
-
rcu_read_lock();
ret = -ESRCH;