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Remove all mention of MTX_NOSWITCH. It was obsoleted a long time ago.

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This commit is contained in:
John Baldwin 2002-09-24 20:45:58 +00:00
parent bf3c8a5270
commit 660e41d37f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=103913
1 changed files with 7 additions and 36 deletions
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43
share/man/man9/mutex.9
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@ -266,7 +266,8 @@ function releases a
mutual exclusion lock;
if a higher priority thread is waiting for the mutex,
the releasing thread will be disconnected
to allow the higher priority thread to acquire the mutex and run.
to allow the higher priority thread to acquire the mutex and run unless
the current thread is executing in a critical section.
.Pp
The
.Fn mtx_unlock_spin
@ -282,28 +283,11 @@ and
functions behave in exactly the same way as do the standard mutex
unlock routines above, while also allowing a
.Fa flags
argument which may only be
.Dv MTX_QUIET
in the
.Fn mtx_unlock_spin_flags
case, and may be one or more of
.Dv MTX_QUIET
and
.Dv MTX_NOSWITCH
in the
.Fn mtx_unlock_flags
case.
argument which may specify
.Dv MTX_QUIET .
The behavior of
.Dv MTX_QUIET
is identical to its behavior in the mutex lock routines.
The
.Dv MTX_NOSWITCH
flag bit signifies,
for a
.Dv MTX_DEF
mutex only,
that the releasing thread is not to be disconnected from the CPU following
the release of the mutex.
.Pp
The
.Fn mtx_destroy
@ -463,24 +447,11 @@ Standard locking and unlocking should be performed with the
and
.Fn mtx_unlock_spin
functions.
If one of these flags is required then, and only then,
should the corresponding flags-accepting routines be used.
Only if a flag is required should the corresponding
flags-accepting routines be used.
.Pp
Options that modify mutex behavior:
.Bl -tag -width MTX_NOSWITCH
.It Dv MTX_NOSWITCH
When releasing a
.Dv MTX_DEF
mutex,
this flag prevents a thread switch that might occur
if another higher priority thread was waiting for the mutex.
This may cause priority inversion and should be used carefully.
This flag can only be passed to
.Fn mtx_unlock_flags .
.Pp
This flag is used internally by the lock code.
It should not be used in general kernel code
and is documented here for completeness only.
.Bl -tag -width MTX_QUIET
.It Dv MTX_QUIET
This option is used to quiet logging messages during individual mutex
operations.