improve cancellation robustness.
Introduce a new file operation, fo_aio_queue, which is responsible for
queueing and completing an asynchronous I/O request for a given file.
The AIO subystem now exports library of routines to manipulate AIO
requests as well as the ability to run a handler function in the
"default" pool of AIO daemons to service a request.
A default implementation for file types which do not include an
fo_aio_queue method queues requests to the "default" pool invoking the
fo_read or fo_write methods as before.
The AIO subsystem permits file types to install a private "cancel"
routine when a request is queued to permit safe dequeueing and cleanup
of cancelled requests.
Sockets now use their own pool of AIO daemons and service per-socket
requests in FIFO order. Socket requests will not block indefinitely
permitting timely cancellation of all requests.
Due to the now-tight coupling of the AIO subsystem with file types,
the AIO subsystem is now a standard part of all kernels. The VFS_AIO
kernel option and aio.ko module are gone.
Many file types may block indefinitely in their fo_read or fo_write
callbacks resulting in a hung AIO daemon. This can result in hung
user processes (when processes attempt to cancel all outstanding
requests during exit) or a hung system. To protect against this, AIO
requests are only permitted for known "safe" files by default. AIO
requests for all file types can be enabled by setting the new
vfs.aio.enable_usafe sysctl to a non-zero value. The AIO tests have
been updated to skip operations on unsafe file types if the sysctl is
zero.
Currently, AIO requests on sockets and raw disks are considered safe
and are enabled by default. aio_mlock() is also enabled by default.
Reviewed by: cem, jilles
Discussed with: kib (earlier version)
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D5289
sbappendstream() does. Although, M_NOTREADY may appear only on SOCK_STREAM
sockets, due to sendfile(2) supporting only the latter, there is a corner
case of AF_UNIX/SOCK_STREAM socket, that still uses records for the sake
of control data, albeit being stream socket.
Provide private version of m_clrprotoflags(), which understands PRUS_NOTREADY,
similar to m_demote().
Use the same scheme implemented to manage credentials.
Code needing to look at process's credentials (as opposed to thred's) is
provided with *_proc variants of relevant functions.
Places which possibly had to take the proc lock anyway still use the proc
pointer to access limits.
why there could appear a zero-sized mbufs in socket buffers.
A proper fix would be to divorce record socket buffers and stream
socket buffers, and divorce pru_send that accepts normal data from
pru_send that accepts control data.
in sbappend_locked() and sbappendrecord_locked().
This is a quick fix to the panic introduced by r274712.
A proper solution should be to make sosend_generic() avoid calling
pru_send() with NULL mbuf for the protocols that do not understand
control messages. Those protocols that understand control messages,
should be able to receive NULL mbuf, if control is non-NULL.
sending not ready data:
o Add new flag to pru_send() flags - PRUS_NOTREADY.
o Add new protocol method pru_ready().
Sponsored by: Nginx, Inc.
Sponsored by: Netflix
o Introduce a notion of "not ready" mbufs in socket buffers. These
mbufs are now being populated by some I/O in background and are
referenced outside. This forces following implications:
- An mbuf which is "not ready" can't be taken out of the buffer.
- An mbuf that is behind a "not ready" in the queue neither.
- If sockbet buffer is flushed, then "not ready" mbufs shouln't be
freed.
o In struct sockbuf the sb_cc field is split into sb_ccc and sb_acc.
The sb_ccc stands for ""claimed character count", or "committed
character count". And the sb_acc is "available character count".
Consumers of socket buffer API shouldn't already access them directly,
but use sbused() and sbavail() respectively.
o Not ready mbufs are marked with M_NOTREADY, and ready but blocked ones
with M_BLOCKED.
o New field sb_fnrdy points to the first not ready mbuf, to avoid linear
search.
o New function sbready() is provided to activate certain amount of mbufs
in a socket buffer.
A special note on SCTP:
SCTP has its own sockbufs. Unfortunately, FreeBSD stack doesn't yet
allow protocol specific sockbufs. Thus, SCTP does some hacks to make
itself compatible with FreeBSD: it manages sockbufs on its own, but keeps
sb_cc updated to inform the stack of amount of data in them. The new
notion of "not ready" data isn't supported by SCTP. Instead, only a
mechanical substitute is done: s/sb_cc/sb_ccc/.
A proper solution would be to take away struct sockbuf from struct
socket and allow protocols to implement their own socket buffers, like
SCTP already does. This was discussed with rrs@.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
The current TSO limitation feature only takes the total number of
bytes in an mbuf chain into account and does not limit by the number
of mbufs in a chain. Some kinds of hardware is limited by two
factors. One is the fragment length and the second is the fragment
count. Both of these limits need to be taken into account when doing
TSO. Else some kinds of hardware might have to drop completely valid
mbuf chains because they cannot loaded into the given hardware's DMA
engine. The new way of doing TSO limitation has been made backwards
compatible as input from other FreeBSD developers and will use
defaults for values not set.
Reviewed by: adrian, rmacklem
Sponsored by: Mellanox Technologies
MFC after: 1 week
buffers drop packets". It was caused by a check for the space available
in a sockbuf, but it was checking the wrong sockbuf.
sys/sys/sockbuf.h
sys/kern/uipc_sockbuf.c
Add sbappendaddr_nospacecheck_locked(), which is just like
sbappendaddr_locked but doesn't validate the receiving socket's
space. Factor out common code into sbappendaddr_locked_internal().
We shouldn't simply make sbappendaddr_locked check the space and
then call sbappendaddr_nospacecheck_locked, because that would cause
the O(n) function m_length to be called twice.
sys/kern/uipc_usrreq.c
Use sbappendaddr_nospacecheck_locked for SOCK_SEQPACKET sockets,
because the receiving sockbuf's size limit is irrelevant.
tests/sys/kern/unix_seqpacket_test.c
Now that 185813 is fixed, pipe_128k_8k fails intermittently due to
185812. Make it fail every time by adding a usleep after starting
the writer thread and before starting the reader thread in
test_pipe. That gives the writer time to fill up its send buffer.
Also, clear the expected failure message due to 185813. It actually
said "185812", but that was a typo.
PR: kern/185813
Reviewed by: silence from freebsd-net@ and rwatson@
MFC after: 3 weeks
Sponsored by: Spectra Logic Corporation
mbufs, but return chain of free mbufs to a caller. Caller can either reuse
them or return to allocator in a batch manner.
- Implement sbdrop()/sbdrop_locked() as a wrapper around sbcut_internal().
- Expose sbcut_locked() for outside usage.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
Approved by: re (marius)
of relying on the tvtohz() workaround. The latter has been introduced
lately by jhb@ (r254699) in order to have a fix that can be backported
to STABLE.
Reported by: Vitja Makarov <vitja.makarov at gmail dot com>
Reviewed by: jhb (earlier version)
mbuf that was fully consumed by the previous call, the mbuf ptr returned by the
current call ends up being the previous mbuf in the sb chain to the one that
contains the data we want.
This does not cause any observable issues because the mbuf copy routines happily
walk the mbuf chain to get to the data at the moff offset, which in this case
means they effectively skip over the mbuf returned by sbsndptr().
We can't adjust sb->sb_sndptr during the previous call for this case because the
next mbuf in the chain may not exist yet. We therefore need to detect the
condition and make the adjustment during the current call.
Fix by detecting the special case of moff being at the start of the next mbuf in
the chain and adjust the required accounting variables accordingly.
Reviewed by: andre
MFC after: 2 weeks
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)
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.
- 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
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
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
(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
- 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
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>
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
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
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.
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().
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.
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.
