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Document some of the kernel API dealing with locks used primarily by VFS.

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Submitted by: Chad David <davidc@acns.ab.ca>
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alfred 2001-07-10 04:22:14 +00:00
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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt BUF_LOCK 9
.Os
.Sh NAME
.Nm BUF_LOCK
.Nd "Locks a buffer"
.Sh SYNOPSIS
.Fd #include <sys/buf.h>
.Ft int
.Fo BUF_LOCK
.Fa "struct buf *bp"
.Fa "int locktype"
.Fc
.Sh DESCRIPTION
The
.Nm
function locks the given buffer. If the lock is already held this
call will block until it can aquire the lock unless LK_NOWAIT is
set.
.Pp
Its arguments are:
.Bl -tag -width locktype
.It Ar bp
The buffer to lock.
.It Ar locktype
Flags controlling the type of lock. See lockmgr(9) for details.
.El
.Sh RETURN VALUES
A value of 0 is returned upon success. See lockmgr(9) for
information on non-zero return values.
.Sh SEE ALSO
.Xr buf 9
.Xr lockmgr 9
.Xr BUF_UNLOCK 9
.Xr BUF_TIMELOCK 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt BUF_LOCKFREE 9
.Os
.Sh NAME
.Nm BUF_LOCKFREE
.Nd "Destroys the buffers lock"
.Sh SYNOPSIS
.Fd #include <sys/buf.h>
.Ft void
.Fo BUF_LOCKFREE
.Fa "struct buf *bp"
.Fc
.Sh DESCRIPTION
The
.Nm
macro destroys the buffer lock. The lock must not be held when
this macro is called or a panic will result.
.Pp
Its argument is:
.Bl -tag
.It Ar bp
The buffer whose lock is to be destroyed.
.Sh SEE ALSO
.Xr buf 9
.Xr lockdestroy 9
.Xr BUF_LOCK 9
.Xr BUF_TIMELOCK 9
.Xr BUF_UNLOCK 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt BUF_LOCKINIT 9
.Os
.Sh NAME
.Nm BUF_LOCKINIT
.Nd "Unlocks a locked buffer"
.Sh SYNOPSIS
.Fd #include <sys/buf.h>
.Ft void
.Fo BUF_LOCKINIT
.Fa "struct buf *bp"
.Fc
.Sh DESCRIPTION
The
.Nm
macro initializes a buffer lock.
.Pp
Its argument is:
.Bl -tag
.It Ar bp
The buffer whose lock it to be initialized.
.Sh SEE ALSO
.Xr buf 9
.Xr lockmgr 9
.Xr lockinit 9
.Xr BUF_LOCK 9
.Xr BUF_TIMELOCK 9
.Xr BUF_UNLOCK 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt BUF_REFCNT 9
.Os
.Sh NAME
.Nm BUF_REFCNT
.Nd "Returns the reference count of the buffer lock"
.Sh SYNOPSIS
.Fd #include <sys/buf.h>
.Ft int
.Fo BUF_REFCNT
.Fa "struct buf *bp"
.Fc
.Sh DESCRIPTION
The
.Nm
function returns the reference count of the buffer lock.
.Pp
Its argument is:
.Bl -tag
.It Ar bp
The buffer whose lock reference count is to be returned.
.Sh SEE ALSO
.Xr buf 9
.Xr lockcount 9
.Xr BUF_LOCK 9
.Xr BUF_TIMELOCK 9
.Xr BUF_UNLOCK 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt BUF_LOCK 9
.Os
.Sh NAME
.Nm BUF_LOCK
.Nd "Locks a buffer"
.Sh SYNOPSIS
.Fd #include <sys/buf.h>
.Ft int
.Fo BUF_LOCK
.Fa "struct buf *bp"
.Fa "int locktype"
.Fa "char *wmesg"
.Fa "int catch"
.Fa "int timo"
.Fc
.Sh DESCRIPTION
The
.Nm
function locks the given buffer, and limits the amount of time it
will sleep to
.Ar timo
and OR's
.Ar catch
into the sleep priority.
.Ar wmesg
is the wmesg used in the sleep.
.Pp
Its arguments are:
.Bl -tag -width locktype
.It Ar bp
The buffer to lock.
.It Ar locktype
Flags controlling the type of lock. See lockmgr(9) for details.
.It Ar wmesg
The wmesg used in any sleeps while aquiring the lock.
.It Ar catch
Priority OR'd into the sleep priority.
.It Ar timo
The timeout for any sleeps encountered during the lock.
.El
.Sh RETURN VALUE
A value of 0 is returned on success. See lockmgr(9) for
details on non-zero return values.
.Sh SEE ALSO
.Xr buf 9
.Xr lockmgr 9
.Xr BUF_UNLOCK 9
.Xr BUF_TIMELOCK 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt BUF_UNLOCK 9
.Os
.Sh NAME
.Nm BUF_UNLOCK
.Nd "Unlocks a locked buffer"
.Sh SYNOPSIS
.Fd #include <sys/buf.h>
.Ft void
.Fo BUF_UNLOCK
.Fa "struct buf *bp"
.Fc
.Sh DESCRIPTION
The
.Nm
function unlocks a buffer that was previously locked with
BUF_LOCK or BUF_TIMELOCK.
.Pp
Its argument is:
.Bl -tag
.It Ar bp
The buffer to unlock. The buffer must already be locked.
.Sh SEE ALSO
.Xr buf 9
.Xr lockmgr 9
.Xr BUF_LOCK 9
.Xr BUF_TIMELOCK 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt LOCKCOUNT 9
.Os
.Sh NAME
.Nm lockcount
.Nd "Returns the reference count of a lock"
.Sh SYNOPSIS
.Fd #include <sys/lockmgr.h>
.Ft int
.Fo lockcount
.Fa "struct lock *lkp"
.Fc
.Sh DESCRIPTION
The
.Nm
function returns the reference count of the lock. The reference
count is the sum of exclusive locks and shared locks.
.Pp
Its arguments are:
.Bl -tag
.It Ar lkp
The lock to return the reference count on.
.El
.Sh RETURN VALUES
An integer greater than or equal to zero.
.Sh SEE ALSO
.Xr lockmgr 9
.Xr lockdestroy 9
.Xr lockstatus 9
.Xr lockmgr_printinfo
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt LOCKDESTROY 9
.Os
.Sh NAME
.Nm lockdestroy
.Nd "Destroys a lock"
.Sh SYNOPSIS
.Fd #include <sys/lockmgr.h>
.Ft int
.Fo lockdestroy
.Fa "struct lock *lkp"
.Fc
.Sh DESCRIPTION
The
.Nm
function destroys the given lock. (Currently is does nothing!)
.Pp
Its arguments are:
.Bl -tag
.It Ar lkp
The lock to destroy
.El
.Sh SEE ALSO
.Xr lockmgr 9
.Xr lockcount 9
.Xr lockstatus 9
.Xr lockmgr_printinfo 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt LOCKMGR 9
.Os
.Sh NAME
.Nm lockmgr
.Nd "Aquires, releases and updates locks"
.Sh SYNOPSIS
.Fd #include <sys/lockmgr.h>
.Ft int
.Fo lockmgr
.Fa "struct lock *lkp"
.Fa "u_int flags"
.Fa "struct mtx *interlkp"
.Fa "struct proc *p"
.Fc
.Sh DESCRIPTION
The
.Nm
function handles general locking functionality within the kernel, including
support for shared and exclusive locks, and recursion. Locks can also be
upgraded and downgraded.
.Pp
Its arguments are:
.Bl -tag -width interlkp
.It Ar lkp
A pointer to lock to manipulate..
.It Ar flags
Flags indicating what action is to be taken.
.Pp
LK_SHARED - Aquire a shared lock. If we currently hold an exclusive lock it will
be downgraded.
.Pp
LK_EXCLUSIVE - Aquire an exclusive lock. If we already hold an exclusive lock
and LK_CANRECURSE is not set we will panic.
.Pp
LK_DOWNGRADE - Downgrade our exclusive lock to a shared lock. Downgrading a shared
lock is not valid. If the exclusive lock has been recursed, all references will
be downgraded.
.Pp
LK_EXCLUPGRADE - Upgrade our lock to an exclusive lock. Will fail with EBUSY if
there is someone ahead of use waiting for an upgrade. If this call fails we loose
our shared lock. Upgrading an exclusive lock will cause a panic.
.Pp
LK_UPGRADE - Upgrades our lock to an exclusive lock. If this call fails we loose
our shared lock. Upgrading an exclusive lock will cause a panic.
.Pp
LK_RELEASE - Release the lock. Releasing a lock that you do not hold can cause
a panic.
.Pp
LK_DRAIN - Waits for all activity on the lock to end, and then marks it decommissioned.
This is used before freeing a lock that is part of a piece of memory that is about to
be freed. (As documented in lockmgr.h)
.Pp
LK_SLEEPFAIL - the we slept for the lock then fail.
.Pp
LK_NOWAIT - Do not allow the call to sleep. This can be used to test the lock.
.Pp
LK_CANRECURSE - It is ok to recurse on an exclusive lock. For every lock there
must be a release.
.Pp
LK_INTERLOCK - Unlock the interlock, which is of course locked already.
.Pp
.It Ar interlkp
An interlock mutex for controlling group access to the lock.
If LK_INTERLOCK is specified
.Nm
assumes
.Ar interlkp
is currently owned and not recursed, and will return it unlocked.
See mtx_assert(9).
.It Ar p
The process responsible for this call. NULL becomes LK_KERNPROC.
.El
.Sh LOCKS
If LK_INTERLOCK is specified then
.Ar interlkp
must be held prior to calling
.Nm
and will be returned unlocked.
.Pp
Upgrade attempts that fail result in the loss of the lock that
is currently held. As well, it is not valid to upgrade an
exclusive lock, and a panic will be the result of trying.
.Sh RETURN VALUES
A value of 0 is returned on success.
.Sh ERRORS
.Bl -tag
.It Bq EBUSY
Either LK_NOWAIT was specified and lockmgr would have slept, or another
process was ahead of you in line for an exclusive upgrade.
.It Bq ENOLCK
LK_SLEEP_FAIL was set and we slept.
.Sh SEE ALSO
.Xr mutex 9
.Xr lockcount 9
.Xr lockdestroy 9
.Xr lockstatus 9
.Xr lockmgr_printinfo 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt LOCKMGR_PRINTINFO 9
.Os
.Sh NAME
.Nm lockmgr_printinfo
.Nd "Prints information about the lock."
.Sh SYNOPSIS
.Fd #include <sys/lockmgr.h>
.Ft void
.Fo lockmgr_printinfo
.Fa "struct lock *lkp"
.Fc
.Sh DESCRIPTION
The
.Nm
function prints information about the lock including the lock
time and the wait count.
.Pp
Its arguments are:
.Bl -tag
.It Ar lkp
The lock to print.
.El
.Sh SEE ALSO
.Xr lockmgr 9
.Xr lockcount 9
.Xr lockdestroy 9
.Xr lockstatus 9
.Sh AUTHORS
This man page was written by Chad David.

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.\"
.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
.\" DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 9, 2001
.Dt LOCKSTATUS 9
.Os
.Sh NAME
.Nm lockstatus
.Nd "Returns the lock status"
.Sh SYNOPSIS
.Fd #include <sys/lockmgr.h>
.Ft int
.Fo lockstatus
.Fa "struct lock *lkp"
.Fa "struct proc *p"
.Fc
.Sh DESCRIPTION
The
.Nm
function returns the status of the lock in relation to the proc
passed to it.
.Pp
Its arguments are:
.Bl -tag
.It Ar lkp
The lock to return the status of.
.It Ar p
The process to check any exclusive locks against. If
.Ar p
is NULL and an exclusive lock is held
.Ar LK_EXCLUSIVE
is returned.
.El
.Sh RETURN VALUES
.Bl -tag
.It Ar LK_EXCLUSIVE
An exclusive lock is held by the process
.Ar p
passed in.
.It Ar LK_EXCLOTHER
An exclusive lock is held by someone other then the process
.Ar p
passed in.
.It Ar LK_SHARED
A shared lock is held.
count is the sum of exclusive locks and shared locks.
.It Ar 0
The lock is not held by anyone.
.El
.Sh SEE ALSO
.Xr lockmgr 9
.Xr lockcount 9
.Xr lockdestroy 9
.Xr lockmgr_printinfo 9
.Sh AUTHORS
This man page was written by Chad David.