mtx_enter(lock, type) becomes:
mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)
similarily, for releasing a lock, we now have:
mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.
The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.
Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:
MTX_QUIET and MTX_NOSWITCH
The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:
mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.
Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.
Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.
Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.
Finally, caught up to the interface changes in all sys code.
Contributors: jake, jhb, jasone (in no particular order)
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.
All calls to mtx_init() for mutexes that recurse must now include
the MTX_RECURSE bit in the flag argument variable. This change is in
preparation for an upcoming (further) mutex API cleanup.
The witness code will call panic() if a lock is found to recurse but
the MTX_RECURSE bit was not set during the lock's initialization.
The old MTX_RECURSE "state" bit (in mtx_lock) has been renamed to
MTX_RECURSED, which is more appropriate given its meaning.
The following locks have been made "recursive," thus far:
eventhandler, Giant, callout, sched_lock, possibly some others declared
in the architecture-specific code, all of the network card driver locks
in pci/, as well as some other locks in dev/ stuff that I've found to
be recursive.
Reviewed by: jhb
slow enough as it is, without having to constantly check that it really
is an i386 still. It was possible to compile out the conditionals for
faster cpus by leaving out 'I386_CPU', but it was not possible to
unconditionally compile for the i386. You got the runtime checking whether
you wanted it or not. This makes I386_CPU mutually exclusive with the
other cpu types, and tidies things up a little in the process.
Reviewed by: alfred, markm, phk, benno, jlemon, jhb, jake, grog, msmith,
jasone, dcs, des (and a bunch more people who encouraged it)
process is on the alternate stack or not. For compatibility
with sigstack(2) state is being updated if such is needed.
We now determine whether the process is on the alternate
stack by looking at its stack pointer. This allows a process
to siglongjmp from a signal handler on the alternate stack
to the place of the sigsetjmp on the normal stack. When
maintaining state, this would have invalidated the state
information and causing a subsequent signal to be delivered
on the normal stack instead of the alternate stack.
PR: 22286
because it only takes a struct tag which makes it impossible to
use unions, typedefs etc.
Define __offsetof() in <machine/ansi.h>
Define offsetof() in terms of __offsetof() in <stddef.h> and <sys/types.h>
Remove myriad of local offsetof() definitions.
Remove includes of <stddef.h> in kernel code.
NB: Kernelcode should *never* include from /usr/include !
Make <sys/queue.h> include <machine/ansi.h> to avoid polluting the API.
Deprecate <struct.h> with a warning. The warning turns into an error on
01-12-2000 and the file gets removed entirely on 01-01-2001.
Paritials reviews by: various.
Significant brucifications by: bde
to accomodate the changes.
Here's a list of things that have changed (I may have left out a few); for a
relatively complete list, see http://people.freebsd.org/~bmilekic/mtx_journal
* Remove old (once useful) mcluster code for MCLBYTES > PAGE_SIZE which
nobody uses anymore. It was great while it lasted, but now we're moving
onto bigger and better things (Approved by: wollman).
* Practically re-wrote the allocation macros in sys/sys/mbuf.h to accomodate
new allocations which grab the necessary lock.
* Make sure that necessary mbstat variables are manipulated with
corresponding atomic() routines.
* Changed the "wait" routines, cleaned it up, made one routine that does
the job.
* Generalized MWAKEUP() macro. Got rid of m_retry and m_retryhdr, as they
are now included in the generalized "wait" routines.
* Sleep routines now use msleep().
* Free lists have locks.
* etc... probably other stuff I'm missing...
Things to look out for and work on later:
* find a better way to (dynamically) adjust EXT_COUNTERS
* move necessity to recurse on a lock from drain routines by providing
lock-free lower-level version of MFREE() (and possibly m_free()?).
* checkout include of mutex.h in sys/sys/mbuf.h - probably violating
general philosophy here.
The code has been reviewed quite a bit, but problems may arise... please,
don't panic! Send me Emails: bmilekic@freebsd.org
Reviewed by: jlemon, cp, alfred, others?
that should be better.
The old code counted references to mbuf clusters by using the offset
of the cluster from the start of memory allocated for mbufs and
clusters as an index into an array of chars, which did the reference
counting. If the external storage was not a cluster then reference
counting had to be done by the code using that external storage.
NetBSD's system of linked lists of mbufs was cosidered, but Alfred
felt it would have locking issues when the kernel was made more
SMP friendly.
The system implimented uses a pool of unions to track external
storage. The union contains an int for counting the references and
a pointer for forming a free list. The reference counts are
incremented and decremented atomically and so should be SMP friendly.
This system can track reference counts for any sort of external
storage.
Access to the reference counting stuff is now through macros defined
in mbuf.h, so it should be easier to make changes to the system in
the future.
The possibility of storing the reference count in one of the
referencing mbufs was considered, but was rejected 'cos it would
often leave extra mbufs allocated. Storing the reference count in
the cluster was also considered, but because the external storage
may not be a cluster this isn't an option.
The size of the pool of reference counters is available in the
stats provided by "netstat -m".
PR: 19866
Submitted by: Bosko Milekic <bmilekic@dsuper.net>
Reviewed by: alfred (glanced at by others on -net)
<sys/bio.h>.
<sys/bio.h> is now a prerequisite for <sys/buf.h> but it shall
not be made a nested include according to bdes teachings on the
subject of nested includes.
Diskdrivers and similar stuff below specfs::strategy() should no
longer need to include <sys/buf.> unless they need caching of data.
Still a few bogus uses of struct buf to track down.
Repocopy by: peter
Remove evil allocation macros from machdep.c (why was that there???) and
use malloc() instead.
Move paramters out of param.h and into the code itself.
Move a bunch of internal definitions from public sys/*.h headers (without
#ifdef _KERNEL even) into the code itself.
I had hoped to make some of this more dynamic, but the cost of doing
wakeups on all sleeping processes on old arrays was too frightening.
The other possibility is to initialize on the first use, and allow
dynamic sysctl changes to parameters right until that point. That would
allow /etc/rc.sysctl to change SEM* and MSG* defaults as we presently
do with SHM*, but without the nightmare of changing a running system.
Exceptions:
Vinum untouched. This means that it cannot be compiled.
Greg Lehey is on the case.
CCD not converted yet, casts to struct buf (still safe)
atapi-cd casts to struct buf to examine B_PHYS
(Much of this done by script)
Move B_ORDERED flag to b_ioflags and call it BIO_ORDERED.
Move b_pblkno and b_iodone_chain to struct bio while we transition, they
will be obsoleted once bio structs chain/stack.
Add bio_queue field for struct bio aware disksort.
Address a lot of stylistic issues brought up by bde.
