- MFC

Unlock process lock when return error from getrobustlist call.

Tested by: Alexander Best <alexbestms at math uni-muenster de>
Approved by: kib (mentor)
MFC after: 3 days

Merge from HEAD

Add KTR(9) tracing for futex emulation.

Approved by: kib (mentor)
MFC after: 1 month

Merge from HEAD

Move extern variable definitions to the header file.

Approved by: kib (mentor)
MFC after: 1 month

Reimplement futexes.
Old implemention used Giant to protect the kernel data structures,
but at the same time called malloc(M_WAITOK), that could cause the
calling thread to sleep and lost Giant prote

Reimplement futexes.
Old implemention used Giant to protect the kernel data structures,
but at the same time called malloc(M_WAITOK), that could cause the
calling thread to sleep and lost Giant protection. User-visible
result was the missed wakeup.

New implementation uses one sx lock per futex. The sx protects
the futex structures and allows to sleep while copyin or copyout
are performed.

Unlike linux, we return EINVAL when FUTEX_CMP_REQUEUE operation
is requested and either caller specified futexes are equial or
second futex already exists. This is acceptable since the situation
can only occur from the application error, and glibc falls back to
old FUTEX_WAKE operation when FUTEX_CMP_REQUEUE returns an error.

Approved by: kib (mentor)
MFC after: 1 month

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Remove support for FUTEX_REQUEUE operation.
Glibc does not use this operation since 2.3.3 version (Jun 2004),
as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
Glibc versions prior to 2.3.3

Remove support for FUTEX_REQUEUE operation.
Glibc does not use this operation since 2.3.3 version (Jun 2004),
as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
FUTEX_REQUEUE returned EINVAL.

Any application directly using FUTEX_REQUEUE without return
value checking are definitely broken.

Limit quantity of messages per process about unsupported
operation.

Approved by: kib (mentor)
MFC after: 1 month

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- Merge from HEAD

Sort include files in the alphabetical order.

Approved by: kib (mentor)
MFC after: 2 weeks

Ignore FUTEX_FD op, as it is done by linux.

Approved by: kib (mentor)
MFC after: 2 weeks

Include linux_futex.h before linux_emul.h

Approved by: kib (mentor)
MFC after: 6 days

In the robust futexes list head, futex_offset shall be signed,
and glibc actually supplies negative offsets. Change l_ulong to l_long.

Submitted by: dchagin

Make robust futexes work on linux32/amd64. Use PTRIN to read
user-mode pointers. Change types used in the structures definitions to
properly-sized architecture-specific types.

Submitted by: dchagin

Make robust futexes work on linux32/amd64. Use PTRIN to read
user-mode pointers. Change types used in the structures definitions to
properly-sized architecture-specific types.

Submitted by: dchagin
MFC after: 1 week

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Implement robust futexes. Most of the code is modelled after
what Linux does. This is because robust futexes are mostly
userspace thing which we cannot alter. Two syscalls maintain
pointer to userspa

Implement robust futexes. Most of the code is modelled after
what Linux does. This is because robust futexes are mostly
userspace thing which we cannot alter. Two syscalls maintain
pointer to userspace list and when process exits a routine
walks this list waking up processes sleeping on futexes
from that list.

Reviewed by: kib (mentor)
MFC after: 1 month

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o Add stub support for some new futex operations,
so the annoying message is not printed.

o Don't warn about FUTEX_FD not being implemented
and return ENOSYS instead of 0 (eg. success).

o Cle

o Add stub support for some new futex operations,
so the annoying message is not printed.

o Don't warn about FUTEX_FD not being implemented
and return ENOSYS instead of 0 (eg. success).

o Clear FUTEX_PRIVATE_FLAG as we actually implement
only private futexes so there is no reason to
return ENOSYS when app asks for a private futex.
We don't reject shared futexes because they worked
just fine with our implementation so far.

Approved by: kib (mentor)
Tested by: bsam
MFC after: 1 week

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Return ENOSYS instead of 0 for the unknown futex operations.

Submitted by: rdivacky
Reported and tested by: Gary Stanley <gary velocity-servers net>

Move futex support code from <arch>/support.s into linux compat directory.
Implement all futex atomic operations in assembler to not depend on the
fuword() that does not allow to distinguish between

Move futex support code from <arch>/support.s into linux compat directory.
Implement all futex atomic operations in assembler to not depend on the
fuword() that does not allow to distinguish between -1 and failure return.
Correctly return 0 from atomic operations on success.

In collaboration with: rdivacky
Tested by: Scot Hetzel <swhetzel gmail com>, Milos Vyletel <mvyletel mzm cz>
Sponsored by: Google SoC 2007

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MFP4: Linux futex support for amd64.

Initial patch was submitted by kib and additional work was done
by Divacky Roman.

Tested by: emulation

MFp4 (110541):
Sync with rev 1.7 in NetBSD.

Obtained from: NetBSD

MFp4 (110523, parts which apply cleanly):
semi-automatic style(9)

The futex stuff already differs a lot (only a small part does not differ)
from NetBSD, so we are already way off and can't apply ch

MFp4 (110523, parts which apply cleanly):
semi-automatic style(9)

The futex stuff already differs a lot (only a small part does not differ)
from NetBSD, so we are already way off and can't apply changes from NetBSD
automatically. As we need to merge everything by hand already, we can even
make the files comply to our world order.

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Change futex lock from mutex to sx. Make futex_get atomic (protected by the
futex lock).

Sponsored by: Google SoC 2006
Submitted by: rdivacky
Suggested by: jhb

- don't wake every sleeper just the first one [1]
- remove debuging printf [2]

Submitted by: intron <mag@intron.ac> [1], rdivacky [2]

Correct the number of retries in a futex_wake() call.

Sponsored by: Google SoC 2006
Submitted by: rdivacky

ifdef DEBUG a printf

Submitted by: rdivacky