Commit Graph

106 Commits

Author SHA1 Message Date
John Baldwin
9351347a17 Cosmetic fixup in output of lock types in show locks output. 2002-04-10 01:19:53 +00:00
John Baldwin
b6396e1656 Add a new char * pointer lo_type to struct lock_object that is used to
point to a more generic name for a lock that is more suitable for use by
witness when grouping locks.  For example, although network driver locks
use the interface name for the name of each lock, they should all use the
same witness and be treated the same as witness.  Another example is that
all UMA zone locks should be treated the same.  The witness code has also
been updated to print out the lock type in addition to the lock name in a
few places where it is relevant.
2002-04-04 20:45:21 +00:00
John Baldwin
c08cf3c3e8 Enforce an implicit lock order of sleepable locks before non-sleepable
locks.
2002-04-02 19:27:21 +00:00
John Baldwin
48c343df5f Explicitly document how we implicitly enforce the lock order of sleep
locks before spin locks.
2002-04-02 16:51:20 +00:00
Jeff Roberson
f22a4b62f5 Add a new mtx_init option "MTX_DUPOK" which allows duplicate acquires of locks
with this flag.  Remove the dup_list and dup_ok code from subr_witness.  Now
we just check for the flag instead of doing string compares.

Also, switch the process lock, process group lock, and uma per cpu locks over
to this interface.  The original mechanism did not work well for uma because
per cpu lock names are unique to each zone.

Approved by:	jhb
2002-03-27 09:23:41 +00:00
Warner Losh
cb9a238a8a Remove last two abuses of cpu_critical_{enter,exit} in the MI code.
Reviewed by: jake, jhb, rwatson
2002-03-21 06:11:09 +00:00
John Baldwin
60e269643d - Use a MI critical section in witness_sleep() and witness_list() as they
simply need to prevent switching from another CPU and do not need
  interrupts disabled.
- Add a comment to witness_list() about why displaying spin locks for
  threads on other CPU's really is just a bad idea and probably shouldn't
  be done.
2002-03-08 18:57:57 +00:00
Peter Wemm
d1693e1701 Back out all the pmap related stuff I've touched over the last few days.
There is some unresolved badness that has been eluding me, particularly
affecting uniprocessor kernels.  Turning off PG_G helped (which is a bad
sign) but didn't solve it entirely.  Userland programs still crashed.
2002-02-27 09:51:33 +00:00
Peter Wemm
6bd95d70db Work-in-progress commit syncing up pmap cleanups that I have been working
on for a while:
- fine grained TLB shootdown for SMP on i386
- ranged TLB shootdowns.. eg: specify a range of pages to shoot down with
  a single IPI, since the IPI is very expensive.  Adjust some callers
  that used to trigger this inside tight loops to do a ranged shootdown
  at the end instead.
- PG_G support for SMP on i386 (options ENABLE_PG_G)
- defer PG_G activation till after we decide what we are going to do with
  PSE and the 4MB pages at the start of the kernel.  This should solve
  some rumored strangeness about stale PG_G entries getting stuck
  underneath the 4MB pages.
- add some instrumentation for the fine TLB shootdown
- convert some asm instruction wrappers from functions to inlines.  gcc
  seems to do a fair bit better with this.
- [temporarily!] pessimize the tlb shootdown IPI handlers.  I will fix
  this again shortly.

This has been working fairly well for me for a while, but I have tweaked
it again prior to commit since my last major testing round.  The only
outstanding problem that I know of is PG_G related, which is why there
is an option for it (not on by default for SMP).  I have seen a world
speedups by a few percent (as much as 4 or 5% in one case) but I have
*not* accurately measured this - I am a bit sceptical of these numbers.
2002-02-25 23:49:51 +00:00
Seigo Tanimura
f591779bb5 Lock struct pgrp, session and sigio.
New locks are:

- pgrpsess_lock which locks the whole pgrps and sessions,
- pg_mtx which protects the pgrp members, and
- s_mtx which protects the session members.

Please refer to sys/proc.h for the coverage of these locks.

Changes on the pgrp/session interface:

- pgfind() needs the pgrpsess_lock held.

- The caller of enterpgrp() is responsible to allocate a new pgrp and
  session.

- Call enterthispgrp() in order to enter an existing pgrp.

- pgsignal() requires a pgrp lock held.

Reviewed by:	jhb, alfred
Tested on:	cvsup.jp.FreeBSD.org
		(which is a quad-CPU machine running -current)
2002-02-23 11:12:57 +00:00
Julian Elischer
079b7badea Pre-KSE/M3 commit.
this is a low-functionality change that changes the kernel to access the main
thread of a process via the linked list of threads rather than
assuming that it is embedded in the process. It IS still embeded there
but remove all teh code that assumes that in preparation for the next commit
which will actually move it out.

Reviewed by: peter@freebsd.org, gallatin@cs.duke.edu, benno rice,
2002-02-07 20:58:47 +00:00
John Baldwin
78a1485fd1 Fixes for alpha pmap on SMP machines:
- Create a private list of active pmaps rather than abusing the list of all
  processes when we need to look up pmaps.  The process list needs a sx lock
  and we can't be getting sx locks in the middle of cpu_switch()
  (pmap_activate() can call pmap_get_asn() from cpu_switch()).  Instead, we
  protect the list with a spinlock.  This also means the list is shorter
  since a pmap can be used by more than one process and we could (at least
  in thoery) dink with pmap's more than once, but now we only touch each
  pmap once when we have to update all of them.
- Wrap pmap_activate()'s code to get a new ASN in an explicit critical section
  so that when it is called while doing an exec() we can't get preempted.
- Replace splhigh() in pmap_growkernel() with a critical section to prevent
  preemption while we are adjusting the kernel page tables.
- Fixes abuse of PCPU_GET(), which doesn't return an L-value.
- Also adds some slight cleanups to the ASN handling by adding some macros
  instead of magic numbers in relation to the ASN and ASN generations.

Reviewed by:	dfr
2002-02-06 04:30:26 +00:00
John Baldwin
c86b6ff551 Change the preemption code for software interrupt thread schedules and
mutex releases to not require flags for the cases when preemption is
not allowed:

The purpose of the MTX_NOSWITCH and SWI_NOSWITCH flags is to prevent
switching to a higher priority thread on mutex releease and swi schedule,
respectively when that switch is not safe.  Now that the critical section
API maintains a per-thread nesting count, the kernel can easily check
whether or not it should switch without relying on flags from the
programmer.  This fixes a few bugs in that all current callers of
swi_sched() used SWI_NOSWITCH, when in fact, only the ones called from
fast interrupt handlers and the swi_sched of softclock needed this flag.
Note that to ensure that swi_sched()'s in clock and fast interrupt
handlers do not switch, these handlers have to be explicitly wrapped
in critical_enter/exit pairs.  Presently, just wrapping the handlers is
sufficient, but in the future with the fully preemptive kernel, the
interrupt must be EOI'd before critical_exit() is called.  (critical_exit()
can switch due to a deferred preemption in a fully preemptive kernel.)

I've tested the changes to the interrupt code on i386 and alpha.  I have
not tested ia64, but the interrupt code is almost identical to the alpha
code, so I expect it will work fine.  PowerPC and ARM do not yet have
interrupt code in the tree so they shouldn't be broken.  Sparc64 is
broken, but that's been ok'd by jake and tmm who will be fixing the
interrupt code for sparc64 shortly.

Reviewed by:	peter
Tested on:	i386, alpha
2002-01-05 08:47:13 +00:00
John Baldwin
422f61655f Remove brain damaged code in witness_lock(). We could have easily
just used PCPU_GET(spinlocks) w/o needing the w_mtx held.  It is more
correct to just check td_critnest now though.
2002-01-05 08:29:54 +00:00
John Baldwin
98f9879242 Introduce a standard name for the lock protecting an interrupt controller
and it's associated state variables: icu_lock with the name "icu".  This
renames the imen_mtx for x86 SMP, but also uses the lock to protect
access to the 8259 PIC on x86 UP.  This also adds an appropriate lock to
the various Alpha chipsets which fixes problems with Alpha SMP machines
dropping interrupts with an SMP kernel.
2001-12-20 23:48:31 +00:00
John Baldwin
7e1f6dfe9d Modify the critical section API as follows:
- The MD functions critical_enter/exit are renamed to start with a cpu_
  prefix.
- MI wrapper functions critical_enter/exit maintain a per-thread nesting
  count and a per-thread critical section saved state set when entering
  a critical section while at nesting level 0 and restored when exiting
  to nesting level 0.  This moves the saved state out of spin mutexes so
  that interlocking spin mutexes works properly.
- Most low-level MD code that used critical_enter/exit now use
  cpu_critical_enter/exit.  MI code such as device drivers and spin
  mutexes use the MI wrappers.  Note that since the MI wrappers store
  the state in the current thread, they do not have any return values or
  arguments.
- mtx_intr_enable() is replaced with a constant CRITICAL_FORK which is
  assigned to curthread->td_savecrit during fork_exit().

Tested on:	i386, alpha
2001-12-18 00:27:18 +00:00
David E. O'Brien
91f9161737 Repeat after me -- "Use of ANSI string concatenation can be bad."
In this case, C99's __func__ is properly defined as:

	static const char __func__[] = "function-name";

and GCC 3.1 will not allow it to be used in bogus string concatenation.
2001-12-10 05:40:12 +00:00
John Baldwin
f4076cc158 Add a couple of returns to making recovering from a failed witness_assert()
more sane in the RESTARTABLE_PANICS case.
2001-11-15 19:46:36 +00:00
John Baldwin
74e4502e62 Replace 'curproc' with 'td->td_proc'. 2001-10-08 21:05:46 +00:00
John Baldwin
0479e3d339 Move the ap boot spin lock earlier in the lock order before the sio(4)
lock since we occasionally call printf() while holding the ap boot lock
which can call down into the sio(4) driver if using a serial console.
2001-10-01 22:50:30 +00:00
John Baldwin
e649bcb506 Remove unneeded proc variables and fix comments. 2001-09-21 21:54:45 +00:00
Julian Elischer
b40ce4165d KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after:    ha ha ha ha
2001-09-12 08:38:13 +00:00
John Baldwin
6385dec00e Style nits:
- Don't use punctuation or newlines in panic messages.
- Remove excess blank lines.

Requested and partially submitted by:	bde
2001-08-24 17:46:58 +00:00
John Baldwin
c19fe5e261 Add witness_upgrade() and witness_downgrade() for handling upgrades and
downgrades of shared/exclusive locks.
2001-08-23 22:47:05 +00:00
John Baldwin
d7c4536a55 Convert some KASSERT()'s into if (foo) panic() because they are testing
how locks are managed by the rest of the kernel, not verifying the internal
integrity of witness itself.
2001-08-23 22:44:47 +00:00
John Baldwin
827dcaf663 Make witness compile w/o DDB.
Reported by:	wpaul
2001-08-10 22:33:59 +00:00
John Baldwin
32bca5fe03 - Fix panicstr checks to explicitly check against NULL.
- Add a few more panicstr checks so that we don't panic recursively.

Requested by:	sheldonh (2)
2001-07-31 17:44:57 +00:00
John Baldwin
a5dd141db6 Add a missing ~ so that the LO_INITIALIZED flag actually gets turned off
in witness_destroy().
2001-07-20 23:29:25 +00:00
John Baldwin
ec178c1e4c Don't check witness assertions if the lock doesn't use witness or witness
is dead.
2001-06-28 22:22:20 +00:00
John Baldwin
04297fe609 - Add a new witness_assert() to perform arbitrary locking assertions.
- Clean up the KTR tracepoints to be slighlty more consistent and useful
- Fix a bug in WITNESS where we would recurse indefinitely and blow the
  stack when acquiring Giant after sleeping with a sleepable lock held.

Reported by:	tanimura (3)
2001-06-27 06:27:29 +00:00
John Baldwin
b7e554f5d6 - Move the 'clk' spinlock below other spin locks since KTR trace events
may need the clock lock for nanotime().
- Add KTR trace events for lock list manipulations and other witness
  operations.
- Use a temporary variable instead of setting the lock list head directly
  and then setting up the links to add a new lock list entry to the lock
  list.  This small race could result in witness "forgetting" about all
  the locks held by this process temporarily during an interrupt.
- Close a more fatal race condition when removing a lock from a list.
  Removing a lock from the list entails both decrementing the count of
  items in this bucket as well as shuffling items in the current bucket up
  a notch to replace the gap left by the removed item.  Wrap these
  operations in a critical section.
2001-06-25 23:17:52 +00:00
Peter Wemm
0978669829 "Fix" the previous initial attempt at fixing TUNABLE_INT(). This time
around, use a common function for looking up and extracting the tunables
from the kernel environment.  This saves duplicating the same function
over and over again.  This way typically has an overhead of 8 bytes + the
path string, versus about 26 bytes + the path string.
2001-06-08 05:24:21 +00:00
Peter Wemm
4422746fdf Back out part of my previous commit. This was a last minute change
and I botched testing.  This is a perfect example of how NOT to do
this sort of thing. :-(
2001-06-07 03:17:26 +00:00
Peter Wemm
81930014ef Make the TUNABLE_*() macros look and behave more consistantly like the
SYSCTL_*() macros.  TUNABLE_INT_DECL() was an odd name because it didn't
actually declare the int, which is what the name suggests it would do.
2001-06-06 22:17:08 +00:00
John Baldwin
1ad5401134 - Don't panic on a try lock operation for a sleep lock if we hold a spin
lock.  Since we won't actually block on a try lock operation, it's not
  a problem.  Add a comment explaining why it is safe to skip lock order
  checking with try locks.
- Remove the ithread list lock spin lock from the order list.
2001-05-17 22:44:56 +00:00
John Baldwin
9e5620599e Check witness_dead in more functions to avoid panic'ing when assertions
fail due to witness exhausting its internal resources and shutting down.

Reported by:	Szilveszter Adam <sziszi@petra.hos.u-szeged.hu>
Tested by:	David Wolfskill <david@catwhisker.org>
2001-05-11 20:25:29 +00:00
John Baldwin
2d96f0b145 - Move state about lock objects out of struct lock_object and into a new
struct lock_instance that is stored in the per-process and per-CPU lock
  lists.  Previously, the lock lists just kept a pointer to each lock held.
  That pointer is now replaced by a lock instance which contains a pointer
  to the lock object, the file and line of the last acquisition of a lock,
  and various flags about a lock including its recursion count.
- If we sleep while holding a sleepable lock, then mark that lock instance
  as having slept and ignore any lock order violations that occur while
  acquiring Giant when we wake up with slept locks.  This is ok because of
  Giant's special nature.
- Allow witness to differentiate between shared and exclusive locks and
  unlocks of a lock.  Witness will now detect the case when a lock is
  acquired first in one mode and then in another.  Mutexes are always
  locked and unlocked exclusively.  Witness will also now detect the case
  where a process attempts to unlock a shared lock while holding an
  exclusive lock and vice versa.
- Fix a bug in the lock list implementation where we used the wrong
  constant to detect the case where a lock list entry was full.
2001-05-04 17:15:16 +00:00
Alfred Perlstein
aad7597ce0 When panic()'ing because of recursion on a non-recursive mutex, print
out the location it was initially locked.

Ok'd by: jake
2001-04-30 01:01:52 +00:00
John Baldwin
9d4f526475 Spelling nit: acquring -> acquiring.
Reported by:	T. William Wells <bill@twwells.com>
2001-04-21 01:50:32 +00:00
John Baldwin
d8915a7f34 - Whoops, forgot to enable the clock lock in the spin order list on the
alpha.
- Change the Debugger() functions to pass in the real function name.
2001-04-19 15:49:54 +00:00
John Baldwin
3c41f323c9 Check to see if enroll() returns NULL in the witness initialization. This
can happen if witness runs out of resources during initialization or if
witness_skipspin is enabled.

Sleuthing by:	Peter Jeremy <peter.jeremy@alcatel.com.au>
2001-04-17 03:35:38 +00:00
John Baldwin
7a9aa5d372 - Add a comment at the start of the spin locks list.
- The alpha SMP code uses an "ap boot" spinlock as well.
2001-04-13 08:31:38 +00:00
Boris Popov
16162e5789 Avoid endless recursion on panic.
Reviewed by:	jhb
2001-04-10 00:56:19 +00:00
John Baldwin
d53d22496f Maintain a reference count on the witness struct. When the reference
count drops to 0 in witness_destroy, set the w_name and w_file pointers
to point to the string "(dead)" and the w_line field to 0.  This way,
if a mutex of a given name is used only in a module, then as long as
all mutexes in the module are destroyed when the module is unloaded,
witness will not maintain stale references to the mutex's name in the
module's data section causing a panic later on when the w_name or w_file
field's are examined.
2001-04-09 22:34:05 +00:00
John Baldwin
3dcb6789d7 - Split out the functionality of displaying the contents of a single lock
list into a public witness_list_locks() function.  Call this function
  twice in witness_list() instead of using an evil goto.
- Adjust the 'show locks' command to take an optional parameter which
  specifies the pid of a process to list the locks of.  By default the
  locks held by the current process are displayed.
2001-04-06 21:37:52 +00:00
John Baldwin
026e76f43e Close a race condition where if we were obtaining a sleep lock and no spin
locks were held, we could be preempted and switch CPU's in between the time
that we set a variable to the list of spin locks on our CPU and the time
that we checked that variable to ensure no spinlocks were held while
grabbing a sleep lock.  Losing the race resulted in checking some other
CPU's spin lock list and bogusly panicing.
2001-03-28 16:11:51 +00:00
John Baldwin
f7012f592a - s/mutexes/locks/g in appropriate comments.
- Rename the 'show mutexes' ddb command to 'show locks' since it shows
  a list of all the lock objects held by the current process.
2001-03-28 12:39:40 +00:00
John Baldwin
192846463a Rework the witness code to work with sx locks as well as mutexes.
- Introduce lock classes and lock objects.  Each lock class specifies a
  name and set of flags (or properties) shared by all locks of a given
  type.  Currently there are three lock classes: spin mutexes, sleep
  mutexes, and sx locks.  A lock object specifies properties of an
  additional lock along with a lock name and all of the extra stuff needed
  to make witness work with a given lock.  This abstract lock stuff is
  defined in sys/lock.h.  The lockmgr constants, types, and prototypes have
  been moved to sys/lockmgr.h.  For temporary backwards compatability,
  sys/lock.h includes sys/lockmgr.h.
- Replace proc->p_spinlocks with a per-CPU list, PCPU(spinlocks), of spin
  locks held.  By making this per-cpu, we do not have to jump through
  magic hoops to deal with sched_lock changing ownership during context
  switches.
- Replace proc->p_heldmtx, formerly a list of held sleep mutexes, with
  proc->p_sleeplocks, which is a list of held sleep locks including sleep
  mutexes and sx locks.
- Add helper macros for logging lock events via the KTR_LOCK KTR logging
  level so that the log messages are consistent.
- Add some new flags that can be passed to mtx_init():
  - MTX_NOWITNESS - specifies that this lock should be ignored by witness.
    This is used for the mutex that blocks a sx lock for example.
  - MTX_QUIET - this is not new, but you can pass this to mtx_init() now
    and no events will be logged for this lock, so that one doesn't have
    to change all the individual mtx_lock/unlock() operations.
- All lock objects maintain an initialized flag.  Use this flag to export
  a mtx_initialized() macro that can be safely called from drivers.  Also,
  we on longer walk the all_mtx list if MUTEX_DEBUG is defined as witness
  performs the corresponding checks using the initialized flag.
- The lock order reversal messages have been improved to output slightly
  more accurate file and line numbers.
2001-03-28 09:03:24 +00:00
John Baldwin
6283b7d01b - Switch from using save/disable/restore_intr to using critical_enter/exit
and change the u_int mtx_saveintr member of struct mtx to a critical_t
  mtx_savecrit.
- On the alpha we no longer need a custom _get_spin_lock() macro to avoid
  an extra PAL call, so remove it.
- Partially fix using mutexes with WITNESS in modules.  Change all the
  _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line
  parameters and rename them to use a prefix of two underscores.  Inside
  of kern_mutex.c, generate wrapper functions for
  _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore)
  that are called from modules.  The macros mtx_{un,}lock_{spin,}_flags()
  are mapped to the __mtx_* macros inside of the kernel to inline the
  usual case of mutex operations and map to the internal _mtx_* functions
  in the module case so that modules will use WITNESS and KTR logging if
  the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
John Baldwin
5db078a9be Fix mtx_legal2block. The only time that it is bad to block on a mutex is
if we hold a spin mutex, since we can trivially get into deadlocks if we
start switching out of processes that hold spinlocks.  Checking to see if
interrupts were disabled was a sort of cheap way of doing this since most
of the time interrupts were only disabled when holding a spin lock.  At
least on the i386.  To fix this properly, use a per-process counter
p_spinlocks that counts the number of spin locks currently held, and
instead of checking to see if interrupts are disabled in the witness code,
check to see if we hold any spin locks.  Since child processes always
start up with the sched lock magically held in fork_exit(), we initialize
p_spinlocks to 1 for child processes.  Note that proc0 doesn't go through
fork_exit(), so it starts with no spin locks held.

Consulting from:	cp
2001-03-09 07:24:17 +00:00