we have to revert to TTYDISC which we know will successfully open
rather than try the previous ldisc which might also fail to open.
Do not let ldisc implementations muck about with ->t_line, and remove
code which checks for reopens, it should never happen.
Move ldisc->l_hotchar to tty->t_hotchar and have ldisc implementation
initialize it in their open routines. Reset to zero when we enter
TTYDISC. ("no" should really be -1 since zero could be a valid
hotchar for certain old european mainframe protocols.)
Thanks to Sam for importing tags in a way that allowed this to be done.
Submitted by: Gleb Smirnoff <glebius@cell.sick.ru>
Also allow the sr and ar drivers to create netgraph versions of their modules.
Document the change to the ksocket node.
- Assert the mutex in NG_IDHASH_FIND() since the mutex is required to
safely walk the node lists in the ng_ID_hash table.
- Acquire the ng_nodelist_mtx when walking ng_allnodes or ng_allhooks
to generate state dump output from the netgraph sysctls.
Only the first link0..link$NLINKS hooks would be utilized, whereas
the link hooks may be connected sparsely.
Add a counter variable so that the link hook array is only traversed
while there is still work to do, but that it continues up to the end
if it has to.
Tweak things so that ng_fec has a chance of working with things
other than ethernet. Use ifp->if_output of the underlying interfaces
and use IF_HANDOFF() rather than depending on ether_output() and
ether_output_frame() explicitly. Also, don't insist that underlying
devices be IFM_ETHER when checking their link states in the link
monitor code.
With these changes, I was able to create a two channel bundle
consisting of one ethernet interface and one 802.11 wireless
device (via ndis). Note that this only works because both devices
use the same if_output vector: ng_fec will not let you bundle
devices with different output vectors together (it really doesn't
make sense to do that).
underlying interfaces rather than using ac_netgraph in struct arpcom.
The latter is meant only for use by ng_ether, and using it breaks
interoperability with the rest of netgraph.
- Lock down low hanging fruit use of sb_flags with socket buffer
lock.
- Lock down low hanging fruit use of so_state with socket lock.
- Lock down low hanging fruit use of so_options.
- Lock down low-hanging fruit use of sb_lowwat and sb_hiwat with
socket buffer lock.
- Annotate situations in which we unlock the socket lock and then
grab the receive socket buffer lock, which are currently actually
the same lock. Depending on how we want to play our cards, we
may want to coallesce these lock uses to reduce overhead.
- Convert a if()->panic() into a KASSERT relating to so_state in
soaccept().
- Remove a number of splnet()/splx() references.
More complex merging of socket and socket buffer locking to
follow.
The big lines are:
NODEV -> NULL
NOUDEV -> NODEV
udev_t -> dev_t
udev2dev() -> findcdev()
Various minor adjustments including handling of userland access to kernel
space struct cdev etc.
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.
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
global mutex, accept_mtx, which serializes access to the following
fields across all sockets:
so_qlen so_incqlen so_qstate
so_comp so_incomp so_list
so_head
While providing only coarse granularity, this approach avoids lock
order issues between sockets by avoiding ownership of the fields
by a specific socket and its per-socket mutexes.
While here, rewrite soclose(), sofree(), soaccept(), and
sonewconn() to add assertions, close additional races and address
lock order concerns. In particular:
- Reorganize the optimistic concurrency behavior in accept1() to
always allocate a file descriptor with falloc() so that if we do
find a socket, we don't have to encounter the "Oh, there wasn't
a socket" race that can occur if falloc() sleeps in the current
code, which broke inbound accept() ordering, not to mention
requiring backing out socket state changes in a way that raced
with the protocol level. We may want to add a lockless read of
the queue state if polling of empty queues proves to be important
to optimize.
- In accept1(), soref() the socket while holding the accept lock
so that the socket cannot be free'd in a race with the protocol
layer. Likewise in netgraph equivilents of the accept1() code.
- In sonewconn(), loop waiting for the queue to be small enough to
insert our new socket once we've committed to inserting it, or
races can occur that cause the incomplete socket queue to
overfill. In the previously implementation, it was sufficient
to simply tested once since calling soabort() didn't release
synchronization permitting another thread to insert a socket as
we discard a previous one.
- In soclose()/sofree()/et al, it is the responsibility of the
caller to remove a socket from the incomplete connection queue
before calling soabort(), which prevents soabort() from having
to walk into the accept socket to release the socket from its
queue, and avoids races when releasing the accept mutex to enter
soabort(), permitting soabort() to avoid lock ordering issues
with the caller.
- Generally cluster accept queue related operations together
throughout these functions in order to facilitate locking.
Annotate new locking in socketvar.h.
the socket is on an accept queue of a listen socket. This change
renames the flags to SQ_COMP and SQ_INCOMP, and moves them to a new
state field on the socket, so_qstate, as the locking for these flags
is substantially different for the locking on the remainder of the
flags in so_state.
behaviour lost in the change from 4.x style netgraph tee nodes.
Alter the tee node to use the new method. Document the behaviour.
Step the ABI version number... old netgraph klds will refuse to load.
Better than just crashing.
Submitted by: Gleb Smirnoff <glebius@cell.sick.ru>
state. Apparently it happens when both devices try to disconnect RFCOMM
multiplexor channel at the same time.
The scenario is as follows:
- local device initiates RFCOMM connection to the remote device. This
creates both RFCOMM multiplexor channel and data channel;
- remote device terminates RFCOMM data channel (inactivity timeout);
- local device acknowledges RFCOMM data channel termination. Because
there is no more active data channels and local device has initiated
connection it terminates RFCOMM multiplexor channel;
- remote device does not acknowledges RFCOMM multiplexor channel
termination. Instead it sends its own request to terminate RFCOMM
multiplexor channel. Even though local device acknowledges RFCOMM
multiplexor channel termination the remote device still keeps
L2CAP connection open.
Because of hanging RFCOMM multiplexor channel subsequent RFCOMM
connections between local and remote devices will fail.
Reported by: Johann Hugo <jhugo@icomtek.csir.co.za>
there so there are no ABI changes);
+ replace 5 redefinitions of the IPF2AC macro with one in if_arp.h
Eventually (but before freezing the ABI) we need to get rid of
struct arpcom (initially with the help of some smart #defines
to avoid having to touch each and every driver, see below).
Apart from the struct ifnet, struct arpcom now only stores a copy
of the MAC address (ac_enaddr, but we already have another copy in
the struct ifnet -- if_addrhead), and a netgraph-specific field
which is _always_ accessed through the ifp, so it might well go
into the struct ifnet too (where, besides, there is already an entry
for AF_NETGRAPH data...)
Too bad ac_enaddr is widely referenced by all drivers. But
this can be fixed as follows:
#define ac_enaddr ac_if.the_original_ac_enaddr_in_struct_ifnet
(note that the right hand side would likely be a pointer rather than
the base address of an array.)
of an interface. No functional change.
On passing, comment an useless invocation of TAILQ_INIT(&ifp->if_addrhead)
which could probably be removed in the interest of clarity.
