Commit Graph

184 Commits

Author SHA1 Message Date
Eitan Adler
3eb9ab5255 Document a large number of currently undocumented sysctls. While here
fix some style(9) issues and reduce redundancy.

PR:		kern/155491
PR:		kern/155490
PR:		kern/155489
Submitted by:	Galimov Albert <wtfcrap@mail.ru>
Approved by:	bde
Reviewed by:	jhb
MFC after:	1 week
2011-12-13 00:38:50 +00:00
Bjoern A. Zeeb
b233773bb9 Increase the defaults for the maximum socket buffer limit,
and the maximum TCP send and receive buffer limits from 256kB
to 2MB.

For sb_max_adj we need to add the cast as already used in the sysctl
handler to not overflow the type doing the maths.

Note that this is just the defaults.  They will allow more memory
to be consumed per socket/connection if needed but not change the
default "idle" memory consumption.   All values are still tunable
by sysctls.

Suggested by:	gnn
Discussed on:	arch (Mar and Aug 2011)
MFC after:	3 weeks
Approved by:	re (kib)
2011-08-25 09:20:13 +00:00
Gleb Smirnoff
443301e296 Revert r194662, since it breaks ng_ksocket(4) and may break
other socket consumers with alternate sb_upcall.

PR:		kern/154676
Submitted by:	Arnaud Lacombe <lacombar gmail.com>
MFC after:	7 days
2011-04-14 14:54:22 +00:00
Andre Oppermann
4ad1c464fe In sbappendstream_locked() demote all incoming packet mbufs (and
chains) to pure data mbufs using m_demote().  This removes the
packet header and all m_tag information as they are not meaningful
anymore on a stream socket where mbufs are linked through m->m_next.
Strictly speaking a packet header can be only ever valid on the first
mbuf in an m_next chain.

sbcompress() was doing this already when the mbuf chain layout lent
itself to it (e.g. header splitting or merge-append), just not
consistently.

This frees resources at socket buffer append time instead of at
sbdrop_internal() time after data has been read from the socket.

For MAC the per packet information has done its duty and during
socket buffer appending the policy of the socket itself takes over.
With the append the packet boundaries disappear naturally and with
it any context that was based on it.  None of the residual information
from mbuf headers in the socket buffer on stream sockets was looked at.
2009-06-22 21:46:40 +00:00
John Baldwin
74fb0ba732 Rework socket upcalls to close some races with setup/teardown of upcalls.
- Each socket upcall is now invoked with the appropriate socket buffer
  locked.  It is not permissible to call soisconnected() with this lock
  held; however, so socket upcalls now return an integer value.  The two
  possible values are SU_OK and SU_ISCONNECTED.  If an upcall returns
  SU_ISCONNECTED, then the soisconnected() will be invoked on the
  socket after the socket buffer lock is dropped.
- A new API is provided for setting and clearing socket upcalls.  The
  API consists of soupcall_set() and soupcall_clear().
- To simplify locking, each socket buffer now has a separate upcall.
- When a socket upcall returns SU_ISCONNECTED, the upcall is cleared from
  the receive socket buffer automatically.  Note that a SO_SND upcall
  should never return SU_ISCONNECTED.
- All this means that accept filters should now return SU_ISCONNECTED
  instead of calling soisconnected() directly.  They also no longer need
  to explicitly clear the upcall on the new socket.
- The HTTP accept filter still uses soupcall_set() to manage its internal
  state machine, but other accept filters no longer have any explicit
  knowlege of socket upcall internals aside from their return value.
- The various RPC client upcalls currently drop the socket buffer lock
  while invoking soreceive() as a temporary band-aid.  The plan for
  the future is to add a new flag to allow soreceive() to be called with
  the socket buffer locked.
- The AIO callback for socket I/O is now also invoked with the socket
  buffer locked.  Previously sowakeup() would drop the socket buffer
  lock only to call aio_swake() which immediately re-acquired the socket
  buffer lock for the duration of the function call.

Discussed with:	rwatson, rmacklem
2009-06-01 21:17:03 +00:00
Maksim Yevmenkin
e72a94adc3 Fix sbappendrecord_locked().
The main problem is that sbappendrecord_locked() relies on sbcompress()
to set sb_mbtail. This will not happen if sbappendrecord_locked() is
called with mbuf chain made of exactly one mbuf (i.e. m0->m_next == NULL).
In this case sbcompress() will be called with m == NULL and will do
nothing. I'm not entirely sure if m == NULL is a valid argument for
sbcompress(), and, it rather pointless to call it like that, but keep
calling it so it can do SBLASTMBUFCHK().

The problem is triggered by the SOCKBUF_DEBUG kernel option that
enables SBLASTRECORDCHK() and SBLASTMBUFCHK() checks.

PR:			kern/126742
Investigated by:	pluknet < pluknet -at- gmail -dot- com >
No response from:	freebsd-current@, freebsd-bluetooth@
MFC after:		3 days
2009-04-21 19:14:13 +00:00
Robert Watson
7978014d3a Rewrite sbreserve_locked()'s comment on NULL thread pointers, eliminating
an XXXRW about the comment being stale.

MFC after:	3 days
2008-10-07 09:51:39 +00:00
Bjoern A. Zeeb
6f4745d575 Catch a possible NULL pointer deref in case the offsets got mangled
somehow.
As a consequence we may now get an unexpected result(*).
Catch that error cases with a well defined panic giving appropriate
pointers to ease debugging.

(*) While the concensus was that the case should never happen unless
    there was a bug, noone was definitively sure.

Discussed with:		kmacy (about 8 months back)
Reviewed by:		silby (as part of a larger patch in March)
MFC after:		2 months
2008-09-07 13:09:04 +00:00
George V. Neville-Neil
49f287f8c5 Update the kernel to count the number of mbufs and clusters
(all types) used per socket buffer.

Add support to netstat to print out all of the socket buffer
statistics.

Update the netstat manual page to describe the new -x flag
which gives the extended output.

Reviewed by:	rwatson, julian
2008-05-15 20:18:44 +00:00
Robert Watson
3f0bfcccfd Further clean up sorflush:
- Expose sbrelease_internal(), a variant of sbrelease() with no
  expectations about the validity of locks in the socket buffer.
- Use sbrelease_internel() in sorflush(), and as a result avoid intializing
  and destroying a socket buffer lock for the temporary stack copy of the
  actual buffer, asb.
- Add a comment indicating why we do what we do, and remove an XXX since
  things have gotten less ugly in sorflush() lately.

This makes socket close cleaner, and possibly also marginally faster.

MFC after:	3 weeks
2008-02-04 12:25:13 +00:00
Robert Watson
265de5bb62 Correct two problems relating to sorflush(), which is called to flush
read socket buffers in shutdown() and close():

- Call socantrcvmore() before sblock() to dislodge any threads that
  might be sleeping (potentially indefinitely) while holding sblock(),
  such as a thread blocked in recv().

- Flag the sblock() call as non-interruptible so that a signal
  delivered to the thread calling sorflush() doesn't cause sblock() to
  fail.  The sblock() is required to ensure that all other socket
  consumer threads have, in fact, left, and do not enter, the socket
  buffer until we're done flushin it.

To implement the latter, change the 'flags' argument to sblock() to
accept two flags, SBL_WAIT and SBL_NOINTR, rather than one M_WAITOK
flag.  When SBL_NOINTR is set, it forces a non-interruptible sx
acquisition, regardless of the setting of the disposition of SB_NOINTR
on the socket buffer; without this change it would be possible for
another thread to clear SB_NOINTR between when the socket buffer mutex
is released and sblock() is invoked.

Reviewed by:	bz, kmacy
Reported by:	Jos Backus <jos at catnook dot com>
2008-01-31 08:22:24 +00:00
Kip Macy
5e0f5cfaed Add SB_NOCOALESCE flag to disable socket buffer update in place 2007-12-17 10:02:01 +00:00
Jeff Roberson
ace8398da0 Refactor select to reduce contention and hide internal implementation
details from consumers.

 - Track individual selecters on a per-descriptor basis such that there
   are no longer collisions and after sleeping for events only those
   descriptors which triggered events must be rescaned.
 - Protect the selinfo (per descriptor) structure with a mtx pool mutex.
   mtx pool mutexes were chosen to preserve api compatibility with
   existing code which does nothing but bzero() to setup selinfo
   structures.
 - Use a per-thread wait channel rather than a global wait channel.
 - Hide select implementation details in a seltd structure which is
   opaque to the rest of the kernel.
 - Provide a 'selsocket' interface for those kernel consumers who wish to
   select on a socket when they have no fd so they no longer have to
   be aware of select implementation details.

Tested by:	kris
Reviewed on:	arch
2007-12-16 06:21:20 +00:00
Mohan Srinivasan
58d14dae6d Set the NFS server sockbuf high watermarks to the system defaults
(up form 32KB). The low highwatermark setting caused UDP fullsock
request drops, throttling thruput greatly.
Reported by: Kris Kennaway
Approved by: re@ (Ken Smith)
2007-10-12 03:56:27 +00:00
Robert Watson
049c3b6cdf Now that sx(9) locks support an interruptible lock acquire primitive,
properly observe the SB_NOINTR flag in sblock.  This restores the
required behavior that lock acquisition be interruptible on the socket
buffer I/O serialization lock to allow threads waiting for I/O to be
signaled even if they aren't the thread currently holding the I/O lock.
With this change, the sblock regression test is again passed.

Reported by:		alfred
sx(9) handiwork:	attilio
2007-05-31 11:51:22 +00:00
Robert Watson
d19e16a72c Generally migrate to ANSI function headers, and remove 'register' use. 2007-05-16 20:41:08 +00:00
Robert Watson
7abab91135 sblock() implements a sleep lock by interlocking SB_WANT and SB_LOCK flags
on each socket buffer with the socket buffer's mutex.  This sleep lock is
used to serialize I/O on sockets in order to prevent I/O interlacing.

This change replaces the custom sleep lock with an sx(9) lock, which
results in marginally better performance, better handling of contention
during simultaneous socket I/O across multiple threads, and a cleaner
separation between the different layers of locking in socket buffers.
Specifically, the socket buffer mutex is now solely responsible for
serializing simultaneous operation on the socket buffer data structure,
and not for I/O serialization.

While here, fix two historic bugs:

(1) a bug allowing I/O to be occasionally interlaced during long I/O
    operations (discovere by Isilon).

(2) a bug in which failed non-blocking acquisition of the socket buffer
    I/O serialization lock might be ignored (discovered by sam).

SCTP portion of this patch submitted by rrs.
2007-05-03 14:42:42 +00:00
Robert Watson
8c799760e1 Following movement of functions from uipc_socket2.c to uipc_socket.c and
uipc_sockbuf.c, clean up and update comments.
2007-03-26 17:05:09 +00:00
Robert Watson
20d9e5e87c Complete removal of uipc_socket2.c by moving the last few functions to
other C files:

- Move sbcreatecontrol() and sbtoxsockbuf() to uipc_sockbuf.c.  While
  sbcreatecontrol() is really an mbuf allocation routine, it does its work
  with awareness of the layout of socket buffer memory.

- Move pru_*() protocol switch stubs to uipc_socket.c where the non-stub
  versions of several of these functions live.  Likewise, move socket state
  transition calls (soisconnecting(), etc) to uipc_socket.c.  Moveo
  sodupsockaddr() and sotoxsocket().
2007-03-26 08:59:03 +00:00
Andre Oppermann
4e02375908 Maintain a pointer and offset pair into the socket buffer mbuf chain to
avoid traversal of the entire socket buffer for larger offsets on stream
sockets.

Adjust tcp_output() make use of it.

Tested by:	gallatin
2007-03-19 18:35:13 +00:00
John Baldwin
86a93d51e3 Use sysctl_handle_long() instead of duplicating it's logic for
kern.ipc.maxsockbuf so that this sysctl works for 32-bit binaries running
on amd64 via compat/freebsd32.

MFC after:	3 days
2006-09-06 21:59:36 +00:00
Robert Watson
050ac26521 Remove 'register'.
Use ANSI C prototypes/function headers.
More deterministically line wrap comments.
2006-08-02 13:01:58 +00:00
Robert Watson
eaa6dfbcc2 Reimplement socket buffer tear-down in sofree(): as the socket is no
longer referenced by other threads (hence our freeing it), we don't need
to set the can't send and can't receive flags, wake up the consumers,
perform two levels of locking, etc.  Implement a fast-path teardown,
sbdestroy(), which flushes and releases each socket buffer.  A manual
dom_dispose of the receive buffer is still required explicitly to GC
any in-flight file descriptors, etc, before flushing the buffer.

This results in a 9% UP performance improvement and 16% SMP performance
improvement on a tight loop of socket();close(); in micro-benchmarking,
but will likely also affect CPU-bound macro-benchmark performance.
2006-08-01 10:30:26 +00:00
Robert Watson
f14cce87dc Remove non-socket buffer routines from uipc_sockbuf.c, and socket buffer
specific routines from uipc_socket2.c following repo-copy.  We might
rethink the location of one or two at some point, but the division was
relatively clean.  uipc_sockbuf.c is now the home of routines that
manipulate socket buffers.
2006-07-24 16:21:31 +00:00
Robert Watson
5908c617bb Several protocol switch functions (pru_abort, pru_detach, pru_sosetlabel)
return void, so don't implement no-op versions of these functions.
Instead, consistently check if those switch pointers are NULL before
invoking them.
2006-07-11 23:18:28 +00:00
Robert Watson
6435cdafa3 Remove now unneeded opt_mac.h and mac.h includes. 2006-07-06 13:25:51 +00:00
Robert Watson
cd3a3a269f Remove sbinsertoob(), sbinsertoob_locked(). They violate (and have
basically always violated) invariannts of soreceive(), which assume
that the first mbuf pointer in a receive socket buffer can't change
while the SB_LOCK sleepable lock is held on the socket buffer,
which is precisely what these functions do.  No current protocols
invoke these functions, and removing them will help discourage them
from ever being used.  I should have removed them years ago, but
lost track of it.

MFC after:	1 week
Prodded almost by accident by:	peter
2006-06-17 22:48:34 +00:00
Robert Watson
b37ffd3189 Move some functions and definitions from uipc_socket2.c to uipc_socket.c:
- Move sonewconn(), which creates new sockets for incoming connections on
  listen sockets, so that all socket allocate code is together in
  uipc_socket.c.

- Move 'maxsockets' and associated sysctls to uipc_socket.c with the
  socket allocation code.

- Move kern.ipc sysctl node to uipc_socket.c, add a SYSCTL_DECL() for it
  to sysctl.h and remove lots of scattered implementations in various
  IPC modules.

- Sort sodealloc() after soalloc() in uipc_socket.c for dependency order
  reasons.  Statisticize soalloc() and sodealloc() as they are now
  required only in uipc_socket.c, and are internal to the socket
  implementation.

After this change, socket allocation and deallocation is entirely
centralized in one file, and uipc_socket2.c consists entirely of socket
buffer manipulation and default protocol switch functions.

MFC after:	1 month
2006-06-10 14:34:07 +00:00
Paul Saab
4f590175b7 Allow for nmbclusters and maxsockets to be increased via sysctl.
An eventhandler is used to update all the various zones that depend
on these values.
2006-04-21 09:25:40 +00:00
Robert Watson
bc725eafc7 Chance protocol switch method pru_detach() so that it returns void
rather than an error.  Detaches do not "fail", they other occur or
the protocol flags SS_PROTOREF to take ownership of the socket.

soclose() no longer looks at so_pcb to see if it's NULL, relying
entirely on the protocol to decide whether it's time to free the
socket or not using SS_PROTOREF.  so_pcb is now entirely owned and
managed by the protocol code.  Likewise, no longer test so_pcb in
other socket functions, such as soreceive(), which have no business
digging into protocol internals.

Protocol detach routines no longer try to free the socket on detach,
this is performed in the socket code if the protocol permits it.

In rts_detach(), no longer test for rp != NULL in detach, and
likewise in other protocols that don't permit a NULL so_pcb, reduce
the incidence of testing for it during detach.

netinet and netinet6 are not fully updated to this change, which
will be in an upcoming commit.  In their current state they may leak
memory or panic.

MFC after:	3 months
2006-04-01 15:42:02 +00:00
Robert Watson
ac45e92ff2 Change protocol switch pru_abort() API so that it returns void rather
than an int, as an error here is not meaningful.  Modify soabort() to
unconditionally free the socket on the return of pru_abort(), and
modify most protocols to no longer conditionally free the socket,
since the caller will do this.

This commit likely leaves parts of netinet and netinet6 in a situation
where they may panic or leak memory, as they have not are not fully
updated by this commit.  This will be corrected shortly in followup
commits to these components.

MFC after:      3 months
2006-04-01 15:15:05 +00:00
Robert Watson
63b01ffd34 Add a sysctl, regression.sonewconn_earlytest, which when options
REGRESSION is enabled, allows user space to dictate that sonewconn()
should skip it's "skip the hard work" check to see if the listen
queue is full, and instead proceed with allocation of a socket and
trimming of the overflowed queue.  This makes it easier to test the
queue overflow logic.

MFC after:	1 month
2006-03-26 22:44:37 +00:00
Robert Watson
92c07a345e Change soabort() from returning int to returning void, since all
consumers ignore the return value, soabort() is required to succeed,
and protocols produce errors here to report multiple freeing of the
pcb, which we hope to eliminate.
2006-03-16 07:03:14 +00:00
John Polstra
ba3612cd5c Fix a bug in the loop in sonewconn that makes room on the incomplete
connection queue for a new connection.  It was removing connections
from the wrong list.

Submitted by:	Paul Mikesell
Sponsored by:	Isilon Systems
MFC after:	1 week
2005-11-22 01:55:29 +00:00
Andre Oppermann
34333b16cd Retire MT_HEADER mbuf type and change its users to use MT_DATA.
Having an additional MT_HEADER mbuf type is superfluous and redundant
as nothing depends on it.  It only adds a layer of confusion.  The
distinction between header mbuf's and data mbuf's is solely done
through the m->m_flags M_PKTHDR flag.

Non-native code is not changed in this commit.  For compatibility
MT_HEADER is mapped to MT_DATA.

Sponsored by:	TCP/IP Optimization Fundraise 2005
2005-11-02 13:46:32 +00:00
Robert Watson
d374e81efd Push the assignment of a new or updated so_qlimit from solisten()
following the protocol pru_listen() call to solisten_proto(), so
that it occurs under the socket lock acquisition that also sets
SO_ACCEPTCONN.  This requires passing the new backlog parameter
to the protocol, which also allows the protocol to be aware of
changes in queue limit should it wish to do something about the
new queue limit.  This continues a move towards the socket layer
acting as a library for the protocol.

Bump __FreeBSD_version due to a change in the in-kernel protocol
interface.  This change has been tested with IPv4 and UNIX domain
sockets, but not other protocols.
2005-10-30 19:44:40 +00:00
Robert Watson
7da7362b95 Re-comment sbcompress() to explain what it is it does; it took me
quite a bit of reading to figure it out, and I want to avoid figuring
it out again.

Convert an if (foo) else printf("this is almost a panic") into a
KASSERT.

MFC after:	3 days
2005-09-18 10:30:10 +00:00
Suleiman Souhlal
571dcd15e2 Fix the recent panics/LORs/hangs created by my kqueue commit by:
- Introducing the possibility of using locks different than mutexes
for the knlist locking. In order to do this, we add three arguments to
knlist_init() to specify the functions to use to lock, unlock and
check if the lock is owned. If these arguments are NULL, we assume
mtx_lock, mtx_unlock and mtx_owned, respectively.

- Using the vnode lock for the knlist locking, when doing kqueue operations
on a vnode. This way, we don't have to lock the vnode while holding a
mutex, in filt_vfsread.

Reviewed by:	jmg
Approved by:	re (scottl), scottl (mentor override)
Pointyhat to:	ssouhlal
Will be happy:	everyone
2005-07-01 16:28:32 +00:00
Robert Watson
83b3d58d05 In the current world order, each socket has two mutexes: a mutex
that protects socket and receive socket buffer state, and a second
mutex to protect send socket buffer state.  In some places, the
mutex shared between the socket and receive socket buffer will be
acquired twice, once by each layer, resulting in some
inconsistency, but providing the abstraction benefit of being able
to more easily separate the two mutexes in the future if desired.

When transitioning a socket to the SS_ISDISCONNECTING or
SS_ISDISCONNECTED states, grab the socket/receive socket buffer lock
once rather than grabbing it as the socket lock, modifying socket
state, then grabbing a second time as the receive lock in order to
modify the socket buffer state to indicate no further data can be
read.  This change is believed to close a race between the change in
socket state and the change in socket buffer state, which for a
remotely initiated close on a UNIX domain socket, resulted in
soreceive() returning ENOTCONN rather than an EOF condition.

A similar race still exists in the case of send, however, and is
harder to fix as the socket and send socket buffer mutexes are not
the same, and we would like to avoid holding combinations of socket
mutexes over sb_upcall until we've finished clarifying the locking
protocol for upcalls.

This change has the side affect of reducing the number of mutex
operations to initiate disconnect or perform disconnect on a
socket by two.

PR:		78824
Rerported by:	Marc Olzheim <marcolz@stack.nl>
MFC after:	2 weeks
2005-05-27 17:16:43 +00:00
Robert Watson
59f21d5ab1 Extend the coverage of the accept and socket mutexes in soisconnected()
so that the socket lock is held over the test-and-set removal of the
accept filter option during connect, and the two socket mutex regions
(transition to connected, perform accept filter) are combined.
2005-03-12 13:39:39 +00:00
Robert Watson
9bfb7389bc When upcalling from a socket in soisconnected() for an accept filter,
call with flag M_DONTWAIT rather than M_TRYWAIT, as we don't want to
do blocking memory allocation (etc) in the netisr.

MFC after:	3 days
2005-03-07 13:50:16 +00:00
Robert Watson
2b85a170d1 Prefer NULL to returning 0 cast to a pointer type.
MFC after:	3 days
2005-02-20 15:56:13 +00:00
Robert Watson
280249a66a In sonewconn(), set the new socket's state to show the protocol-provided
connection status before inserting the new socket into the listen
socket's accept queue, or there might be a race in which another thread
wakes up when the accept lock is released, and sees the socket before its
state is set correctly.  The wakeup still occurs after the accept lock is
released.  There have been no diagnoses of this bug in real-world systems
(as yet).

MFC after:	3 days
2005-02-17 12:53:45 +00:00
Warner Losh
9454b2d864 /* -> /*- for copyright notices, minor format tweaks as necessary 2005-01-06 23:35:40 +00:00
Robert Watson
1ef121cf6b In sonewconn(), the s/if/while/ change to wait for room at the tail of
the accept queue is a feature, not a bug/issue, so remove the XXXRW
from the comment.
2004-12-23 01:16:21 +00:00
Maxim Konovalov
2899faf96b Fix a typo in a comparison appeared in rev. 1.125.
Submitted by:	JINMEI Tatuya
2004-10-27 05:37:58 +00:00
Andre Oppermann
312c75c362 Support for dynamically loadable and unloadable protocols within existing protocol
families.

The protosw[] array of any particular protocol family ("domain") is of fixed size
defined at compile time.  This made it impossible to dynamically add or remove any
protocols to or from it.  We work around this by introducing so called SPACER's
which are embedded into the protosw[] array at compile time.  The SPACER's have
a special protocol number (32767) to indicate the fact that they are SPACER's but
are otherwise NULL.  Only as many protocols can be dynamically loaded as SPACER's
are provided in the protosw[] structure.

The pr_usrreqs structure is treated more special and contains pointers to dummy
functions only returning EOPNOTSUPP.  This is needed because the use of those
functions pointers is usually not checked within the kernel because until now it
was assumed to be a valid function pointer.  Instead of fixing all potential
callers we just return a proper error code.

Two new functions provide a clean API to register and unregister a protocol.  The
register function expects a pointer to a valid and complete struct protosw including
a pointer to struct pru_usrreqs provided by the caller.  Upon successful registration
the pr_init() function will be called to finish initialization of the protocol.  The
unregister function restores the SPACER in place of the protocol again.  It is the
responseability of the caller to ensure proper closing of all sockets and freeing
of memory allocation by the unloading protocol.

 sys/protosw.h

  o Define generic PROTO_SPACER to be 32767
  o Prototypes for all pru_*_notsupp() functions
  o Prototypes for pf_proto_[un]register() functions

 kern/uipc_domain.c

  o Global struct pr_usrreqs nousrreqs containing valid pointers to the
    pru_*_notsupp() functions
  o New functions pf_proto_[un]register()

 kern/uipc_socket2.c

  o New functions bodies for all pru_*_notsupp() functions
2004-10-19 15:13:30 +00:00
John-Mark Gurney
ad3b9257c2 Add locking to the kqueue subsystem. This also makes the kqueue subsystem
a more complete subsystem, and removes the knowlege of how things are
implemented from the drivers.  Include locking around filter ops, so a
module like aio will know when not to be unloaded if there are outstanding
knotes using it's filter ops.

Currently, it uses the MTX_DUPOK even though it is not always safe to
aquire duplicate locks.  Witness currently doesn't support the ability
to discover if a dup lock is ok (in some cases).

Reviewed by:	green, rwatson (both earlier versions)
2004-08-15 06:24:42 +00:00
Robert Watson
1e4d7da707 Reduce the number of unnecessary unlock-relocks on socket buffer mutexes
associated with performing a wakeup on the socket buffer:

- When performing an sbappend*() followed by a so[rw]wakeup(), explicitly
  acquire the socket buffer lock and use the _locked() variants of both
  calls.  Note that the _locked() sowakeup() versions unlock the mutex on
  return.  This is done in uipc_send(), divert_packet(), mroute
  socket_send(), raw_append(), tcp_reass(), tcp_input(), and udp_append().

- When the socket buffer lock is dropped before a sowakeup(), remove the
  explicit unlock and use the _locked() sowakeup() variant.  This is done
  in soisdisconnecting(), soisdisconnected() when setting the can't send/
  receive flags and dropping data, and in uipc_rcvd() which adjusting
  back-pressure on the sockets.

For UNIX domain sockets running mpsafe with a contention-intensive SMP
mysql benchmark, this results in a 1.6% query rate improvement due to
reduce mutex costs.
2004-06-26 19:10:39 +00:00
Robert Watson
3f11a2f374 Introduce sbreserve_locked(), which asserts the socket buffer lock on
the socket buffer having its limits adjusted.  sbreserve() now acquires
the lock before calling sbreserve_locked().  In soreserve(), acquire
socket buffer locks across read-modify-writes of socket buffer fields,
and calls into sbreserve/sbrelease; make sure to acquire in keeping
with the socket buffer lock order.  In tcp_mss(), acquire the socket
buffer lock in the calling context so that we have atomic read-modify
-write on buffer sizes.
2004-06-24 01:37:04 +00:00