success and a proper errno value on failure. This makes it
consistent with cv_timedwait(), and paves the way for the
introduction of functions such as sema_timedwait_sig() which can
fail in multiple ways.
Bump __FreeBSD_version and add a note to UPDATING.
Approved by: scottl (ips driver), arch
flags relating to several aspects of socket functionality. This change
breaks out several bits relating to send and receive operation into a
new per-socket buffer field, sb_state, in order to facilitate locking.
This is required because, in order to provide more granular locking of
sockets, different state fields have different locking properties. The
following fields are moved to sb_state:
SS_CANTRCVMORE (so_state)
SS_CANTSENDMORE (so_state)
SS_RCVATMARK (so_state)
Rename respectively to:
SBS_CANTRCVMORE (so_rcv.sb_state)
SBS_CANTSENDMORE (so_snd.sb_state)
SBS_RCVATMARK (so_rcv.sb_state)
This facilitates locking by isolating fields to be located with other
identically locked fields, and permits greater granularity in socket
locking by avoiding storing fields with different locking semantics in
the same short (avoiding locking conflicts). In the future, we may
wish to coallesce sb_state and sb_flags; for the time being I leave
them separate and there is no additional memory overhead due to the
packing/alignment of shorts in the socket buffer structure.
SOCK_LOCK(so):
- Hold socket lock over calls to MAC entry points reading or
manipulating socket labels.
- Assert socket lock in MAC entry point implementations.
- When externalizing the socket label, first make a thread-local
copy while holding the socket lock, then release the socket lock
to externalize to userspace.
order definition for witness. Send lock before receive lock, and
socket locks after accept but before select:
filedesc -> accept -> so_snd -> so_rcv -> sellck
All routing locks after send lock:
so_rcv -> radix node head
All protocol locks before socket locks:
unp -> so_snd
udp -> udpinp -> so_snd
tcp -> tcpinp -> so_snd
reference count:
- Assert SOCK_LOCK(so) macros that directly manipulate so_count:
soref(), sorele().
- Assert SOCK_LOCK(so) in macros/functions that rely on the state of
so_count: sofree(), sotryfree().
- Acquire SOCK_LOCK(so) before calling these functions or macros in
various contexts in the stack, both at the socket and protocol
layers.
- In some cases, perform soisdisconnected() before sotryfree(), as
this could result in frobbing of a non-present socket if
sotryfree() actually frees the socket.
- Note that sofree()/sotryfree() will release the socket lock even if
they don't free the socket.
Submitted by: sam
Sponsored by: FreeBSD Foundation
Obtained from: BSD/OS
protect fields in the socket buffer. Add accessor macros to use the
mutex (SOCKBUF_*()). Initialize the mutex in soalloc(), and destroy
it in sodealloc(). Add addition, add SOCK_*() access macros which
will protect most remaining fields in the socket; for the time being,
use the receive socket buffer mutex to implement socket level locking
to reduce memory overhead.
Submitted by: sam
Sponosored by: FreeBSD Foundation
Obtained from: BSD/OS
global and allocated variables. This strategy is derived from work
originally developed by BSDi for BSD/OS, and applied to FreeBSD by Sam
Leffler:
- Add unp_mtx, a global mutex which will protect all UNIX domain socket
related variables, structures, etc.
- Add UNP_LOCK(), UNP_UNLOCK(), UNP_LOCK_ASSERT() macros.
- Acquire unp_mtx on entering most UNIX domain socket code,
drop/re-acquire around calls into VFS, and release it on return.
- Avoid performing sodupsockaddr() while holding the mutex, so in general
move to allocating storage before acquiring the mutex to copy the data.
- Make a stack copy of the xucred rather than copying out while holding
unp_mtx. Copy the peer credential out after releasing the mutex.
- Add additional assertions of vnode locks following VOP_CREATE().
A few notes:
- Use of an sx lock for the file list mutex may cause problems with regard
to unp_mtx when garbage collection passed file descriptors.
- The locking in unp_pcblist() for sysctl monitoring is correct subject to
the unpcb zone not returning memory for reuse by other subsystems
(consistent with similar existing concerns).
- Sam's version of this change, as with the BSD/OS version, made use of
both a global lock and per-unpcb locks. However, in practice, the
global lock covered all accesses, so I have simplified out the unpcb
locks in the interest of getting this merged faster (reducing the
overhead but not sacrificing granularity in most cases). We will want
to explore possibilities for improving lock granularity in this code in
the future.
Submitted by: sam
Sponsored by: FreeBSD Foundatiuon
Obtained from: BSD/OS 5 snapshot provided by BSDi
(time grows downward)
thread 1 thread 2
------------|------------
dec ref_cnt |
| dec ref_cnt <-- ref_cnt now zero
cmpset |
free all |
return |
|
alloc again,|
reuse prev |
ref_cnt |
| cmpset, read
| already freed
| ref_cnt
------------|------------
This should fix that by performing only a single
atomic test-and-set that will serve to decrement
the ref_cnt, only if it hasn't changed since the
earlier read, otherwise it'll loop and re-read.
This forces ordering of decrements so that truly
the thread which did the LAST decrement is the
one that frees.
This is how atomic-instruction-based refcnting
should probably be handled.
Submitted by: Julian Elischer
Add two new functions: ttyref() and ttyrel(). ttymalloc() creates a struct
tty with a reference count of one. when ttyrel sees the count go to zero,
struct tty is freed.
Hold references for open ttys and for ttys which are controlling terminal
for sessions.
Until drivers start using ttyrel(), this commit will make no difference.
when I reordered events in accept1() to allocate a file descriptor
earlier, I didn't properly update use of goto on exit to unwind for
cases where the file descriptor is now held, but wasn't previously.
The result was that, in the event of accept() on a non-blocking socket,
or in the event of a socket error, a file descriptor would be leaked.
This ended up being non-fatal in many cases, as the file descriptor
would be properly GC'd on process exit, so only showed up for processes
that do a lot of non-blocking accept() calls, and also live for a long
time (such as qmail).
This change updates the use of goto targets to do additional unwinding.
Eyes provided by: Brian Feldman <green@freebsd.org>
Feet, hands provided by: Stefan Ehmann <shoesoft@gmx.net>,
Dimitry Andric <dimitry@andric.com>
Arjan van Leeuwen <avleeuwen@piwebs.com>
is generic to any threading system. This commit does not link this
file to the build yet, nor does it remove these functions from their
current location in kern_thread.c. (that commit coming up after further review)
with an ASUS A7N8X-E motherboard in APIC mode, since storming interrupts
don't repeat immediately. Use DELAY(1) to wait a bit for them to repeat.
This affects all systems. Only delay for the first
(10 * intr_storm_threshold) interrupts (per interrupt handler) so that
this is only a pessimization while warming up. Throttle after calling
the sub-handlers instead of before so that the long delay given by
throttling can be used instead of the DELAY(1) to detect storms after
warming up.
Reduced the throttling period from 1/10 second to 1/hz seconds so that
throttling doesn't destroy performance so much. Interrupts that are
detected as storming are effectively handled by polling at a frequency
of hz Hz. On A7N8X-E's there is another hardware or configuration bug
that makes the throttled frequency closer to 2*hz Hz.
tree, output an empty string instead of "?". This is already what
happened with DEVICE_SYSCTL_LOCATION and DEVICE_SYSCTL_PNPINFO. This
makes the output of "sysctl dev" much nicer (it won't display those
empty sysctls).
Reviewed by: des
size_t and size_t *, respectively. Update callers for the new interface.
This is a better fix for overflows that occurred when dumping segments
larger than 2GB to core files.
called ttyldoptim().
Use this function from all the relevant drivers.
I belive no drivers finger linesw[] directly anymore, paving the way for
locking and refcounting.
class variables in addition to per-device variables. In plain English,
this means that dev.foo0.bar is now called dev.foo.0.bar, and it is
possible to to have dev.foo.bar as well.
double NULL entries signal Witness to stop processing the array of
order entries meaning none of the spin locks are added resulting in
panics on boot.
- Add a missing NULL, NULL terminator to the Slip locks list to keep them
separate from the spin locks.
