37a9d912b2
The cmpxchg_futex_value_locked API was funny in that it returned either
the original, user-exposed futex value OR an error code such as -EFAULT.
This was confusing at best, and could be a source of livelocks in places
that retry the cmpxchg_futex_value_locked after trying to fix the issue
by running fault_in_user_writeable().
This change makes the cmpxchg_futex_value_locked API more similar to the
get_futex_value_locked one, returning an error code and updating the
original value through a reference argument.
Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com> [tile]
Acked-by: Tony Luck <tony.luck@intel.com> [ia64]
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michal Simek <monstr@monstr.eu> [microblaze]
Acked-by: David Howells <dhowells@redhat.com> [frv]
Cc: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110311024851.GC26122@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
23 lines
852 B
C
23 lines
852 B
C
/*
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* arch/s390/uaccess.h
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*
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* Copyright IBM Corp. 2007
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*
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*/
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#ifndef __ARCH_S390_LIB_UACCESS_H
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#define __ARCH_S390_LIB_UACCESS_H
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extern size_t copy_from_user_std(size_t, const void __user *, void *);
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extern size_t copy_to_user_std(size_t, void __user *, const void *);
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extern size_t strnlen_user_std(size_t, const char __user *);
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extern size_t strncpy_from_user_std(size_t, const char __user *, char *);
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extern int futex_atomic_cmpxchg_std(int *, int __user *, int, int);
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extern int futex_atomic_op_std(int, int __user *, int, int *);
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extern size_t copy_from_user_pt(size_t, const void __user *, void *);
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extern size_t copy_to_user_pt(size_t, void __user *, const void *);
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extern int futex_atomic_op_pt(int, int __user *, int, int *);
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extern int futex_atomic_cmpxchg_pt(int *, int __user *, int, int);
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#endif /* __ARCH_S390_LIB_UACCESS_H */
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