This enables locking consumers to pass their own structures around as const and
be able to assert locks embedded into those structures.
Reviewed by: ed, kib, jhb
event. Locking primitives that support this (mtx, rw, and sx) now each
include their own foo_sleep() routine.
- Rename msleep() to _sleep() and change it's 'struct mtx' object to a
'struct lock_object' pointer. _sleep() uses the recently added
lc_unlock() and lc_lock() function pointers for the lock class of the
specified lock to release the lock while the thread is suspended.
- Add wrappers around _sleep() for mutexes (mtx_sleep()), rw locks
(rw_sleep()), and sx locks (sx_sleep()). msleep() still exists and
is now identical to mtx_sleep(), but it is deprecated.
- Rename SLEEPQ_MSLEEP to SLEEPQ_SLEEP.
- Rewrite much of sleep.9 to not be msleep(9) centric.
- Flesh out the 'RETURN VALUES' section in sleep.9 and add an 'ERRORS'
section.
- Add __nonnull(1) to _sleep() and msleep_spin() so that the compiler will
warn if you try to pass a NULL wait channel. The functions already have
a KASSERT to that effect.
- Replace 'process' with 'thread' everywhere.
- Update several places to note that that the fact that default mutexes
may adaptively spin isn't necessarily MD, but is just part of the
implementation as a whole.
- Clarify the text about MTX_SPIN mutexes only being appropriate for
INTR_FAST interrupts or other low level scheduler code to make the
jargon more FreeBSD-ish rather than BSD/OS-ish.
- Also, note that it is possible that interrupts aren't blocked but just
deferred when a spin lock is held (the whole blocked vs. deferred bit is
an MD implementation detail).
- Remove statements saying that spin locks must be released in the exact
opposite order that they were acquired. This stopped being true several
years ago when we first added critical sections that stored their state
in the current thread rather than in struct mtx.
- Note that a mutex must be initialized before it is passed to any other
mutex function, not just mtx_lock.
- Clarify that mtx_trylock() only operates on MTX_DEF mutexes.
- Simplify the text about possible preemption during a mtx_unlock().
- Use complete English sentences in place of phrases in a few places.
- Clarify that it isn't ever safe to sleep with a mutex held. The kernel
tends to panic when you do that.
Requested by: scottl (7)
MFC after: 3 days
holding the mutex, say it will "block". Later in this manual page
we say that sleeping while holding a mutex isn't allowed, and this
can be confusing.
Submitted by: jhb
which may surprise developers coming from Solaris, or other platforms
which have a similar interface, but slightly different rules.
Reviewed by: jhb, ru
cd src/share; find man[1-9] -type f|xargs perl -pi -e 's/[ \t]+$//'
BTW, what editors are the culprits? I'm using vim and it shows
me whitespace at EOL in troff files with a thick blue block...
Reviewed by: Silence from cvs diff -b
MFC after: 7 days
<sys/mutex.h> due to #include spam in <sys/mutex.h>. (More precisely,
<sys/time.h> is the prerequisite, but that is provided by standard
#include spam in <sys/param.h>.)
Fixed bitrot in prototype for mtx_init().
initialization until after malloc() is safe to call, then iterate through
all mutexes and complete their initialization.
This change is necessary in order to avoid some circular bootstrapping
dependencies.
