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3f08bd8bce
freebsd-skq/sys/kern
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John Baldwin 3f08bd8bce Add a basic reader/writer lock implementation to the kernel. This 
implementation is by no means perfect as far as some of the algorithms
that it uses and the fact that it is missing some functionality (try
locks and upgrades/downgrades are not there yet), however it does seem
to work in my local testing.  There is more detail in the comments in the
code, but the short version follows.

A reader/writer lock is very much like a regular mutex: it cannot be held
across a voluntary sleep; it can be acquired in an interrupt thread; if
the lock is held by a writer then the priority of any threads that block
on the lock will be lent to the owner; the simple case lock operations all
are done in a single atomic op.  It also shares some similiarities
with sx locks: it supports reader/writer semantics (multiple readers,
but single writers); readers are allowed to recurse, but writers are not.

We can extend this implementation further by either improving algorithms
or adding new functionality, but this should at least give us a base to
work with now.

Reviewed by:	arch (in theory)
Tested on:	i386 (4 cpu box with a kernel module that used 4 threads
		that randomly chose between read locks and write locks
		that ran w/o panicing for over a day solid.  It usually
		panic'd within a few seconds when there were bugs during
		testing. :)  The kernel module source is available on
		request.)
2006-01-27 23:13:26 +00:00
..
bus_if.m /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
clock_if.m /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
cpufreq_if.m Introduce a new method, cpufreq_drv_type(), that returns the type of the 2005-02-18 00:23:36 +00:00
device_if.m /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
genassym.sh
imgact_aout.c Maintain the lock on the vnode for most of exec_elfN_imgact(). 2005-12-24 04:57:50 +00:00
imgact_elf32.c
imgact_elf64.c
imgact_elf.c Avoid a vm object reference leak in a rarely used code path. 2006-01-21 20:11:49 +00:00
imgact_gzip.c Maintain the lock on the vnode for most of exec_elfN_imgact(). 2005-12-24 04:57:50 +00:00
imgact_shell.c Fix a panic which could occur parsing #!-lines in a shell-script. If the 2005-06-19 02:21:03 +00:00
inflate.c Normalize a significant number of kernel malloc type names: 2005-10-31 15:41:29 +00:00
init_main.c Moderate rewrite of kernel ktrace code to attempt to generally improve 2005-11-13 13:27:44 +00:00
init_sysent.c Regen. 2006-01-22 06:01:48 +00:00
kern_acct.c Significant refactoring of the accounting code to improve locking and VFS 2005-11-12 10:45:13 +00:00
kern_acl.c Implement new world order in VFS locking for ACLs. This will remove the 2005-09-17 22:01:14 +00:00
kern_alq.c Grr. Backout previous change. vn_open_cred() will call NDFREE() on failure. 2006-01-27 11:25:06 +00:00
kern_clock.c Tweak how the MD code calls the fooclock() methods some. Instead of 2005-12-22 22:16:09 +00:00
kern_condvar.c Contributions from XFS for FreeBSD project: 2005-12-12 00:02:22 +00:00
kern_conf.c Novel idea, don't print a string if it is NULL! 2006-01-12 19:15:14 +00:00
kern_context.c
kern_cpu.c make saved cpu level stackable. 2005-10-03 06:57:29 +00:00
kern_descrip.c Return EBADF rather than EINVAL for FWRITE failure as per POSIX. 2006-01-06 16:30:30 +00:00
kern_environment.c Reorder statements to avoid accessing unknown memory. 2005-09-26 14:14:55 +00:00
kern_event.c Add in kqueue support to LIO event notification and fix how it handled 2005-10-12 17:51:31 +00:00
kern_exec.c Remove unneeded calls to pmap_remove_all(). The given page is not mapped. 2005-12-11 22:06:57 +00:00
kern_exit.c Hopefully fix the "calcru: runtime went backwards from ..." problem by 2006-01-23 19:15:13 +00:00
kern_fork.c Moderate rewrite of kernel ktrace code to attempt to generally improve 2005-11-13 13:27:44 +00:00
kern_idle.c Divorce critical sections from spinlocks. Critical sections as denoted by 2005-04-04 21:53:56 +00:00
kern_intr.c Add a swi_remove() function to teardown software interrupt handlers. For 2005-10-26 15:51:05 +00:00
kern_jail.c Push Giant down in jails. Pass the MPSAFE flag to NDINIT, and keep track 2005-09-28 00:30:56 +00:00
kern_kse.c Cleanup some signal interfaces. Now the tdsignal function accepts 2005-11-03 04:49:16 +00:00
kern_kthread.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
kern_ktr.c Whitespace. 2006-01-27 23:06:08 +00:00
kern_ktrace.c Fix a vnode reference leak in the ktrace code. We always grab a reference 2006-01-23 21:45:32 +00:00
kern_linker.c Fix a bug in the kernel module runtime linker that made it impossible 2005-10-19 20:40:30 +00:00
kern_lock.c - Remove and unused include. 2005-12-23 21:32:40 +00:00
kern_lockf.c Print name of device instead of useless major/minor numbers. 2005-03-29 08:13:01 +00:00
kern_mac.c Standard Giant push down operations for the Mandatory Access Control (MAC) 2005-10-04 14:32:58 +00:00
kern_malloc.c Improve memguard a bit: 2005-12-30 11:45:07 +00:00
kern_mbuf.c In mb_zinit_pack() explicitly ignore the return value of uma_zalloc_arg(). 2006-01-23 15:49:01 +00:00
kern_mib.c mp_ncpus is always (properly) initialized, even on UP kernels, so just use it. 2005-08-21 18:03:31 +00:00
kern_module.c Swap the arguments for CP so we copy the correct source and 2005-02-18 22:14:40 +00:00
kern_mtxpool.c Make a bunch of malloc types static. 2005-02-10 12:02:37 +00:00
kern_mutex.c - Add support for having both a shared and exclusive queue of threads in 2006-01-27 22:42:12 +00:00
kern_ntptime.c Explicitly acquire Giant around the ntp_gettime() and assert it in the 2005-05-28 14:34:41 +00:00
kern_physio.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
kern_pmc.c Fix -Wundef. 2005-12-04 02:12:43 +00:00
kern_poll.c - Don't pollute opt_global.h with DEVICE_POLLING and introduce 2005-10-05 10:09:17 +00:00
kern_proc.c Return the thread name in the kinfo_proc structure. 2006-01-18 20:27:43 +00:00
kern_prot.c Use the refcount API to manage the reference count for user credentials 2005-09-27 18:09:42 +00:00
kern_resource.c Back out changes made in rev. 1.151. 2006-01-25 02:05:47 +00:00
kern_rwlock.c Add a basic reader/writer lock implementation to the kernel. This 2006-01-27 23:13:26 +00:00
kern_sema.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
kern_shutdown.c Don't pretend to be thread0 when calling sync(). 2005-09-22 15:34:15 +00:00
kern_sig.c Avoid kernel panic when attaching a process which may not be stopped 2005-12-24 02:59:29 +00:00
kern_subr.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
kern_switch.c Trim trailing whitespace. 2005-12-28 17:13:31 +00:00
kern_sx.c Add a new file (kern/subr_lock.c) for holding code related to struct 2006-01-17 16:55:17 +00:00
kern_synch.c patch(1) and I aren't friends today. Axe a duplicate copy of 2005-12-29 21:15:32 +00:00
kern_syscalls.c
kern_sysctl.c Touch all the pages wired by sysctl_wire_old_buffer() to avoid PTE 2006-01-25 01:03:34 +00:00
kern_tc.c Start time_uptime with 1 instead of 0. 2005-09-19 22:16:31 +00:00
kern_thr.c Add a new feature to thr_kill, if thread ID argument is -1, send 2006-01-07 03:15:21 +00:00
kern_thread.c Now SIGCHLD is always queued. 2005-12-09 02:27:55 +00:00
kern_time.c Fix compiling warning on 64 bits system. 2005-12-09 13:16:48 +00:00
kern_timeout.c Oops, missed adding the required include. 2005-09-15 20:20:36 +00:00
kern_umtx.c do umtx_wake at userland thread exit address, so that others userland 2005-10-26 06:55:46 +00:00
kern_uuid.c Add parse_uuid() that creates a binary representation of an UUID from 2005-10-07 13:37:10 +00:00
kern_xxx.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
ksched.c /* -> /*- for license, minor formatting changes 2005-01-07 02:29:27 +00:00
link_elf_obj.c Make our ELF64 type definitions match standards. In particular this 2005-12-18 04:52:37 +00:00
link_elf.c Make our ELF64 type definitions match standards. In particular this 2005-12-18 04:52:37 +00:00
linker_if.m /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
Make.tags.inc
Makefile Add a 'sysent' target that depends on the various files built from 2005-07-13 20:50:17 +00:00
makesyscalls.sh Introduce a new field in the syscalls.master file format to hold the 2005-05-30 15:09:18 +00:00
md4c.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
md5c.c Fix an 11 year old mistake: Let the hash functions take a void* instead 2006-01-17 15:35:57 +00:00
p1003_1b.c Actually commit the code for kern_sched_get_rr_interval(). 2005-03-31 22:54:48 +00:00
posix4_mib.c Back when VOP_* was introduced, we did not have new-style struct 2004-12-01 23:16:38 +00:00
sched_4bsd.c Move HWPMC_HOOKS into its own opt_hwpmc_hooks.h file. It doesn't merit 2005-06-24 00:16:57 +00:00
sched_ule.c Use variable i instead of variable cpus as an index to get correct kseq. 2005-12-27 12:02:03 +00:00
subr_acl_posix1e.c Implement new world order in VFS locking for ACLs. This will remove the 2005-09-17 22:01:14 +00:00
subr_autoconf.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
subr_blist.c
subr_bus.c Add a devd(8) event that is sent after the system resumes. This can be 2006-01-22 01:06:25 +00:00
subr_clist.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
subr_clock.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
subr_devstat.c - Remove two mtx_asserts that can incorrectly trigger if 2005-05-03 10:58:05 +00:00
subr_disk.c When calling bioq_first() to see if a queue is empty in bioq_disksort(), 2006-01-13 23:27:12 +00:00
subr_eventhandler.c eliminate potential null deref 2005-02-23 19:32:29 +00:00
subr_hints.c The resource_xxx routines in subr_hints.c are called before and after the 2005-07-31 10:46:55 +00:00
subr_kdb.c Add stoppcbs[] arrays on Alpha and sparc64 and have each CPU save its 2005-11-03 21:08:20 +00:00
subr_kobj.c Increment kobj_lookup_misses on a miss rather than decrementing it. 2005-12-29 18:00:42 +00:00
subr_lock.c Add a basic reader/writer lock implementation to the kernel. This 2006-01-27 23:13:26 +00:00
subr_log.c Use dynamic major number allocation. 2005-02-27 22:02:03 +00:00
subr_mbpool.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
subr_mchain.c Change API of mb_copy_t in libmchain so that netsmb can handle 2005-07-29 13:22:37 +00:00
subr_module.c
subr_msgbuf.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
subr_param.c Partially revert revision 1.66, which contained a change that did not 2005-10-14 19:15:10 +00:00
subr_pcpu.c Fix 'show allpcpu' ddb command on non-x86. CPU IDs are in the range 0 .. 2005-11-03 21:06:29 +00:00
subr_power.c General consensus is that it would be even better to run this in a 2005-11-09 16:22:56 +00:00
subr_prf.c Acquire Giant in uprintf() and tprintf() rather than asserting it. In 2005-09-26 08:02:24 +00:00
subr_prof.c Change the addupc_*() functions to use the uintfptr_t type for pc rather 2005-12-16 22:08:32 +00:00
subr_rman.c Prefer NULL to 0. 2005-11-17 08:56:21 +00:00
subr_rtc.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
subr_sbuf.c Make sbuf_copyin() return the number of bytes copied on success. 2005-12-23 11:49:53 +00:00
subr_scanf.c
subr_sleepqueue.c Add a new ddb command 'show sleepq'. It takes a wait channel as an 2006-01-27 22:24:07 +00:00
subr_smp.c Rename the KDB_STOP_NMI kernel option to STOP_NMI and make it apply to all 2005-10-24 21:04:19 +00:00
subr_stack.c Add 'depth' argument to CTRSTACK() macro, which allows to reduce number 2005-08-29 11:34:08 +00:00
subr_taskqueue.c Add the following to the taskqueue api: 2006-01-14 01:55:24 +00:00
subr_trap.c Moderate rewrite of kernel ktrace code to attempt to generally improve 2005-11-13 13:27:44 +00:00
subr_turnstile.c - Add support for having both a shared and exclusive queue of threads in 2006-01-27 22:42:12 +00:00
subr_unit.c Remove debugging printfs. 2005-03-14 06:51:29 +00:00
subr_witness.c Axe KTR_ALQ_MASK now that KTR_WITNESS is off unless you hack an #ifdef 2006-01-25 14:57:23 +00:00
sys_generic.c Return error from fget_write() rather than hardcoding EBADF now that 2006-01-06 16:34:22 +00:00
sys_pipe.c In pipe_write(): when uiomove() fails, do not spin on it forever. 2005-12-16 18:32:39 +00:00
sys_process.c Avoid kernel panic when attaching a process which may not be stopped 2005-12-24 02:59:29 +00:00
sys_socket.c Introduce three additional MAC Framework and MAC Policy entry points to 2005-04-16 18:46:29 +00:00
syscalls.c Regen. 2006-01-22 06:01:48 +00:00
syscalls.master Make aio code MP safe. 2006-01-22 05:59:27 +00:00
sysv_ipc.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
sysv_msg.c Add much needed descriptions for a number of the IPC related sysctl OIDs. 2005-02-12 01:22:39 +00:00
sysv_sem.c Gratuitous renaming of four System V Semaphore MAC Framework entry 2005-06-07 05:03:28 +00:00
sysv_shm.c Re-order MAC and DAC checks in shmget() in order to give precedence to 2005-10-04 16:40:20 +00:00
tty_compat.c Move the old BSD4.3 tty compatibility from (!BURN_BRIDGES && COMPAT_43) 2006-01-10 09:19:10 +00:00
tty_conf.c
tty_cons.c Use dynamic major number allocation for /dev/console, there is no 2005-02-27 21:52:42 +00:00
tty_pts.c Merge a bunch of changes that where done in tty_pty.c after tty_pts.c was 2006-01-27 15:13:40 +00:00
tty_pty.c Don't attempt to re-create the /dev entry for the slave part if it already 2006-01-26 20:54:49 +00:00
tty_subr.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
tty_tty.c Merge the dev_clone and dev_clone_cred event handlers into a single 2005-08-08 19:55:32 +00:00
tty.c Move the old BSD4.3 tty compatibility from (!BURN_BRIDGES && COMPAT_43) 2006-01-10 09:19:10 +00:00
uipc_accf.c o setsockopt(2) cannot remove accept filter. [1] 2005-06-11 11:59:48 +00:00
uipc_cow.c Previously, nothing prevented the page that was returned by pmap_extract() 2005-10-23 07:41:56 +00:00
uipc_domain.c /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
uipc_mbuf2.c Define four constants, MBUF_{,MEM,CLUSTER,PACKET,TAG}_MEM_NAME, which 2005-07-17 14:04:03 +00:00
uipc_mbuf.c When using m_dup(9) to copy more than MHLEN bytes of data, don't create an 2005-12-14 23:34:26 +00:00
uipc_mqueue.c Replace selwakeuppri with selwakeup, let scheduler figure out 2005-12-16 15:01:16 +00:00
uipc_proto.c Use sparse initializers for "struct domain" and "struct protosw", 2005-11-09 13:29:16 +00:00
uipc_sem.c Convert remaining functions to ANSI C function declarations. 2006-01-22 00:30:46 +00:00
uipc_sockbuf.c Fix a bug in the loop in sonewconn that makes room on the incomplete 2005-11-22 01:55:29 +00:00
uipc_socket2.c Fix a bug in the loop in sonewconn that makes room on the incomplete 2005-11-22 01:55:29 +00:00
uipc_socket.c Add sosend_dgram(), a greatly reduced and simplified version of sosend() 2006-01-13 10:22:01 +00:00
uipc_syscalls.c Reformat socket control messages on input/output for 32bit compatibility 2005-10-31 21:09:56 +00:00
uipc_usrreq.c XXX a comment in uipc_usrreq.c that requires updating. 2006-01-13 00:00:32 +00:00
vfs_acl.c Implement new world order in VFS locking for ACLs. This will remove the 2005-09-17 22:01:14 +00:00
vfs_aio.c Just like dofilewrite(), call bwillwrite before fo_write. 2006-01-27 08:02:25 +00:00
vfs_bio.c Remove an unnecessary call to pmap_remove_all(). The given page is not 2006-01-23 00:00:45 +00:00
vfs_cache.c - Fix a leaked reference to a vnode via v_dd. We rely on cache_purge() and 2005-06-17 01:05:13 +00:00
vfs_cluster.c Changes imported from XFS for FreeBSD project: 2005-12-07 03:39:08 +00:00
vfs_default.c Add marker vnodes to ensure that all vnodes associated with the mount point are 2006-01-09 20:42:19 +00:00
vfs_export.c Normalize a significant number of kernel malloc type names: 2005-10-31 15:41:29 +00:00
vfs_extattr.c Tweak previous vfs_lookup.c commit to return an EINVAL error from 2006-01-22 19:37:02 +00:00
vfs_hash.c Normalize a significant number of kernel malloc type names: 2005-10-31 15:41:29 +00:00
vfs_init.c Remove VFS_START(). Its original purpose involved the mfs filesystem, 2005-02-20 23:02:20 +00:00
vfs_lookup.c Tweak previous vfs_lookup.c commit to return an EINVAL error from 2006-01-22 19:37:02 +00:00
vfs_mount.c vfs_busy can only return something useful if MNTK_UNMOUNT has been set. 2006-01-15 20:14:11 +00:00
vfs_subr.c Convert remaining functions in vfs_subr.c from K&R prototypes to ANSI C 2006-01-21 19:42:10 +00:00
vfs_syscalls.c Tweak previous vfs_lookup.c commit to return an EINVAL error from 2006-01-22 19:37:02 +00:00
vfs_vnops.c Eradicate caddr_t from the VFS API. 2005-12-14 00:49:52 +00:00
vnode_if.src Eradicate caddr_t from the VFS API. 2005-12-14 00:49:52 +00:00