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futex: Update comments and docs about return values of arch futex code

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commit 427503519739e779c0db8afe876c1b33f3ac60ae upstream.

The architecture implementations of 'arch_futex_atomic_op_inuser()' and
'futex_atomic_cmpxchg_inatomic()' are permitted to return only -EFAULT,
-EAGAIN or -ENOSYS in the case of failure.

Update the comments in the asm-generic/ implementation and also a stray
reference in the robust futex documentation.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Will Deacon 2019-04-10 11:51:54 +01:00 committed by Greg Kroah-Hartman
parent 4423a82cbd
commit a319c8ff4f
2 changed files with 7 additions and 4 deletions
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3
Documentation/robust-futexes.txt
View file

@ -218,5 +218,4 @@ All other architectures should build just fine too - but they won't have
the new syscalls yet.
Architectures need to implement the new futex_atomic_cmpxchg_inatomic()
inline function before writing up the syscalls (that function returns
-ENOSYS right now).
inline function before writing up the syscalls.

8
include/asm-generic/futex.h
View file

@ -23,7 +23,9 @@
*
* Return:
* 0 - On success
* <0 - On error
* -EFAULT - User access resulted in a page fault
* -EAGAIN - Atomic operation was unable to complete due to contention
* -ENOSYS - Operation not supported
*/
static inline int
arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
@ -85,7 +87,9 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
*
* Return:
* 0 - On success
* <0 - On error
* -EFAULT - User access resulted in a page fault
* -EAGAIN - Atomic operation was unable to complete due to contention
* -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
*/
static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,