linux-toradex.git/kernel/futex/futex.h, branch v5.19

futex: add missing rtmutex.h include

2022-04-07T13:09:12+00:00

This isn't included here any more since the removal of ww_mutex.h from
seqlock.h which causes a build break.

Signed-off-by: Christian König 
Acked-by: Shashank Sharma 
Fixes: e84815cbbc76 ("seqlock: drop seqcount_ww_mutex_t")
Link: https://patchwork.freedesktop.org/patch/msgid/20220407114619.961750-1-christian.koenig@amd.com

futex: Remove futex_cmpxchg detection

2021-11-24T23:02:28+00:00

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

futex: Fix PREEMPT_RT build

2021-10-19T15:27:05+00:00

Mike reported that rcuwait went walk-about and is causing failures on
the PREEMPT_RT builds, restore it.

Reported-by: Mike Galbraith 
Signed-off-by: Peter Zijlstra (Intel)

futex: Implement sys_futex_waitv()

2021-10-07T11:51:11+00:00

Add support to wait on multiple futexes. This is the interface
implemented by this syscall:

futex_waitv(struct futex_waitv *waiters, unsigned int nr_futexes,
	    unsigned int flags, struct timespec *timeout, clockid_t clockid)

struct futex_waitv {
	__u64 val;
	__u64 uaddr;
	__u32 flags;
	__u32 __reserved;
};

Given an array of struct futex_waitv, wait on each uaddr. The thread
wakes if a futex_wake() is performed at any uaddr. The syscall returns
immediately if any waiter has *uaddr != val. *timeout is an optional
absolute timeout value for the operation. This syscall supports only
64bit sized timeout structs. The flags argument of the syscall should be
empty, but it can be used for future extensions. Flags for shared
futexes, sizes, etc. should be used on the individual flags of each
waiter.

__reserved is used for explicit padding and should be 0, but it might be
used for future extensions. If the userspace uses 32-bit pointers, it
should make sure to explicitly cast it when assigning to waitv::uaddr.

Returns the array index of one of the woken futexes. There’s no given
information of how many were woken, or any particular attribute of it
(if it’s the first woken, if it is of the smaller index...).

Signed-off-by: André Almeida 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20210923171111.300673-17-andrealmeid@collabora.com

futex: Simplify double_lock_hb()

2021-10-07T11:51:11+00:00

We need to make sure that all requeue operations take the hash bucket
locks in the same order to avoid deadlock. Simplify the current
double_lock_hb implementation by making sure hb1 is always the
"smallest" bucket to avoid extra checks.

[André: Add commit description]
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: André Almeida 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: André Almeida 
Link: https://lore.kernel.org/r/20210923171111.300673-16-andrealmeid@collabora.com

futex: Split out wait/wake

2021-10-07T11:51:11+00:00

Move the wait/wake bits into their own file.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: André Almeida 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: André Almeida 
Link: https://lore.kernel.org/r/20210923171111.300673-15-andrealmeid@collabora.com

futex: Split out requeue

2021-10-07T11:51:10+00:00

Move all the requeue bits into their own file.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: André Almeida 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: André Almeida 
Link: https://lore.kernel.org/r/20210923171111.300673-14-andrealmeid@collabora.com

futex: Split out PI futex

2021-10-07T11:51:09+00:00

Move the PI futex implementation into it's own file.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: André Almeida 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: André Almeida 
Link: https://lore.kernel.org/r/20210923171111.300673-10-andrealmeid@collabora.com

futex: Split out syscalls

2021-10-07T11:51:07+00:00

Put the syscalls in their own little file.

Signed-off-by: Peter Zijlstra (Intel) 
Suggested-by: Thomas Gleixner 
Signed-off-by: André Almeida 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: André Almeida 
Link: https://lore.kernel.org/r/20210923171111.300673-3-andrealmeid@collabora.com