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
This commit is contained in:
Arnd Bergmann
Thomas Gleixner
parent
3f2bedabb6
commit
3297481d68
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@ -32,7 +32,6 @@ config ARC
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select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARC_MMU_V4
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select HAVE_DEBUG_STACKOVERFLOW
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select HAVE_DEBUG_KMEMLEAK
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select HAVE_IOREMAP_PROT
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select HAVE_KERNEL_GZIP
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select HAVE_KERNEL_LZMA
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@ -92,7 +92,6 @@ config ARM
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select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
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select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG
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select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !(THUMB2_KERNEL && CC_IS_CLANG)
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select HAVE_GCC_PLUGINS
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select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
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select HAVE_IRQ_TIME_ACCOUNTING
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@ -194,7 +194,6 @@ config ARM64
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select HAVE_REGS_AND_STACK_ACCESS_API
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select HAVE_POSIX_CPU_TIMERS_TASK_WORK
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select HAVE_FUNCTION_ARG_ACCESS_API
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select MMU_GATHER_RCU_TABLE_FREE
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select HAVE_RSEQ
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select HAVE_STACKPROTECTOR
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@ -52,7 +52,6 @@ config CSKY
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select HAVE_FUNCTION_TRACER
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select HAVE_FUNCTION_GRAPH_TRACER
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select HAVE_FUNCTION_ERROR_INJECTION
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select HAVE_FUTEX_CMPXCHG if FUTEX && SMP
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select HAVE_FTRACE_MCOUNT_RECORD
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select HAVE_KERNEL_GZIP
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select HAVE_KERNEL_LZO
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@ -20,7 +20,6 @@ config M68K
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select HAVE_ASM_MODVERSIONS
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select HAVE_DEBUG_BUGVERBOSE
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select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_HAS_NO_UNALIGNED
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select HAVE_FUTEX_CMPXCHG if MMU && FUTEX
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select HAVE_MOD_ARCH_SPECIFIC
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select HAVE_UID16
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select MMU_GATHER_NO_RANGE if MMU
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@ -83,7 +83,6 @@ config RISCV
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select HAVE_DMA_CONTIGUOUS if MMU
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select HAVE_EBPF_JIT if MMU
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select HAVE_FUNCTION_ERROR_INJECTION
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select HAVE_GCC_PLUGINS
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select HAVE_GENERIC_VDSO if MMU && 64BIT
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select HAVE_IRQ_TIME_ACCOUNTING
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@ -165,7 +165,6 @@ config S390
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select HAVE_FUNCTION_ERROR_INJECTION
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select HAVE_FUNCTION_GRAPH_TRACER
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select HAVE_FUNCTION_TRACER
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select HAVE_GCC_PLUGINS
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select HAVE_GENERIC_VDSO
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select HAVE_IOREMAP_PROT if PCI
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@ -34,7 +34,6 @@ config SUPERH
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select HAVE_FAST_GUP if MMU
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select HAVE_FUNCTION_GRAPH_TRACER
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select HAVE_FUNCTION_TRACER
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select HAVE_FTRACE_MCOUNT_RECORD
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select HAVE_HW_BREAKPOINT
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select HAVE_IOREMAP_PROT if MMU && !X2TLB
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@ -14,7 +14,6 @@ config UML
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select HAVE_ARCH_SECCOMP_FILTER
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select HAVE_ASM_MODVERSIONS
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select HAVE_UID16
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select HAVE_DEBUG_KMEMLEAK
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select HAVE_DEBUG_BUGVERBOSE
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select NO_DMA if !UML_DMA_EMULATION
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@ -348,7 +348,6 @@ EXPORT_SYMBOL(arch_futex_atomic_op_inuser);
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* 0 - On success
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* -EFAULT - User access resulted in a page fault
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* -EAGAIN - Atomic operation was unable to complete due to contention
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* -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
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*/
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int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
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@ -31,7 +31,6 @@ config XTENSA
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select HAVE_DMA_CONTIGUOUS
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select HAVE_EXIT_THREAD
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select HAVE_FUNCTION_TRACER
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select HAVE_FUTEX_CMPXCHG if !MMU && FUTEX
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select HAVE_HW_BREAKPOINT if PERF_EVENTS
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select HAVE_IRQ_TIME_ACCOUNTING
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select HAVE_PCI
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@ -1592,14 +1592,6 @@ config FUTEX_PI
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depends on FUTEX && RT_MUTEXES
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default y
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config HAVE_FUTEX_CMPXCHG
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bool
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depends on FUTEX
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help
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Architectures should select this if futex_atomic_cmpxchg_inatomic()
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is implemented and always working. This removes a couple of runtime
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checks.
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config EPOLL
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bool "Enable eventpoll support" if EXPERT
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default y
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@ -41,11 +41,6 @@
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#include "futex.h"
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#include "../locking/rtmutex_common.h"
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#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
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int __read_mostly futex_cmpxchg_enabled;
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#endif
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/*
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* The base of the bucket array and its size are always used together
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* (after initialization only in futex_hash()), so ensure that they
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@ -776,9 +771,6 @@ static void exit_robust_list(struct task_struct *curr)
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unsigned long futex_offset;
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int rc;
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if (!futex_cmpxchg_enabled)
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return;
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/*
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* Fetch the list head (which was registered earlier, via
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* sys_set_robust_list()):
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@ -874,9 +866,6 @@ static void compat_exit_robust_list(struct task_struct *curr)
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compat_long_t futex_offset;
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int rc;
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if (!futex_cmpxchg_enabled)
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return;
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/*
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* Fetch the list head (which was registered earlier, via
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* sys_set_robust_list()):
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@ -950,8 +939,6 @@ static void exit_pi_state_list(struct task_struct *curr)
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struct futex_hash_bucket *hb;
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union futex_key key = FUTEX_KEY_INIT;
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if (!futex_cmpxchg_enabled)
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return;
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/*
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* We are a ZOMBIE and nobody can enqueue itself on
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* pi_state_list anymore, but we have to be careful
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@ -1125,26 +1112,6 @@ void futex_exit_release(struct task_struct *tsk)
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futex_cleanup_end(tsk, FUTEX_STATE_DEAD);
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}
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static void __init futex_detect_cmpxchg(void)
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{
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#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
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u32 curval;
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/*
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* This will fail and we want it. Some arch implementations do
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* runtime detection of the futex_atomic_cmpxchg_inatomic()
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* functionality. We want to know that before we call in any
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* of the complex code paths. Also we want to prevent
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* registration of robust lists in that case. NULL is
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* guaranteed to fault and we get -EFAULT on functional
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* implementation, the non-functional ones will return
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* -ENOSYS.
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*/
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if (futex_cmpxchg_value_locked(&curval, NULL, 0, 0) == -EFAULT)
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futex_cmpxchg_enabled = 1;
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#endif
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}
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static int __init futex_init(void)
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{
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unsigned int futex_shift;
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@ -1163,8 +1130,6 @@ static int __init futex_init(void)
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futex_hashsize, futex_hashsize);
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futex_hashsize = 1UL << futex_shift;
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futex_detect_cmpxchg();
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for (i = 0; i < futex_hashsize; i++) {
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atomic_set(&futex_queues[i].waiters, 0);
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plist_head_init(&futex_queues[i].chain);
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@ -27,12 +27,6 @@
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#define FLAGS_CLOCKRT 0x02
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#define FLAGS_HAS_TIMEOUT 0x04
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#ifdef CONFIG_HAVE_FUTEX_CMPXCHG
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#define futex_cmpxchg_enabled 1
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#else
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extern int __read_mostly futex_cmpxchg_enabled;
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#endif
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#ifdef CONFIG_FAIL_FUTEX
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extern bool should_fail_futex(bool fshared);
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#else
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@ -29,8 +29,6 @@
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SYSCALL_DEFINE2(set_robust_list, struct robust_list_head __user *, head,
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size_t, len)
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{
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if (!futex_cmpxchg_enabled)
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return -ENOSYS;
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/*
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* The kernel knows only one size for now:
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*/
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@ -56,9 +54,6 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
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unsigned long ret;
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struct task_struct *p;
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if (!futex_cmpxchg_enabled)
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return -ENOSYS;
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rcu_read_lock();
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ret = -ESRCH;
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@ -103,17 +98,6 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
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return -ENOSYS;
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}
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switch (cmd) {
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case FUTEX_LOCK_PI:
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case FUTEX_LOCK_PI2:
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case FUTEX_UNLOCK_PI:
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case FUTEX_TRYLOCK_PI:
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case FUTEX_WAIT_REQUEUE_PI:
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case FUTEX_CMP_REQUEUE_PI:
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if (!futex_cmpxchg_enabled)
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return -ENOSYS;
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}
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switch (cmd) {
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case FUTEX_WAIT:
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val3 = FUTEX_BITSET_MATCH_ANY;
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@ -323,9 +307,6 @@ COMPAT_SYSCALL_DEFINE2(set_robust_list,
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struct compat_robust_list_head __user *, head,
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compat_size_t, len)
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{
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if (!futex_cmpxchg_enabled)
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return -ENOSYS;
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if (unlikely(len != sizeof(*head)))
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return -EINVAL;
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@ -342,9 +323,6 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
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unsigned long ret;
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struct task_struct *p;
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if (!futex_cmpxchg_enabled)
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return -ENOSYS;
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rcu_read_lock();
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ret = -ESRCH;
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