Commit Graph

2446 Commits

Author SHA1 Message Date
kmacy
9bc55ad7bd revert to opt-in flowtable 2009-06-09 21:55:28 +00:00
oleg
1980405dfd Close long existed race with net.inet.ip.fw.one_pass = 0:
If packet leaves ipfw to other kernel subsystem (dummynet, netgraph, etc)
it carries pointer to matching ipfw rule. If this packet then reinjected back
to ipfw, ruleset processing starts from that rule. If rule was deleted
meanwhile, due to existed race condition panic was possible (as well as
other odd effects like parsing rules in 'reap list').

P.S. this commit changes ABI so userland ipfw related binaries should be
recompiled.

MFC after:	1 month
Tested by:	Mikolaj Golub
2009-06-09 21:27:11 +00:00
kmacy
8fdb55dd41 make flowtable opt-out 2009-06-09 20:27:30 +00:00
kmacy
110a6b7b9d move jenkins hash to its own header in libkern 2009-06-09 20:21:40 +00:00
kmacy
3f394b4e78 - add drbr routines for accessing #qentries and conditionally dequeueing
- track bytes enqueued in buf_ring
2009-06-09 19:19:16 +00:00
bz
675aab46a1 Remove one INET dependency by calling the general
AF agnostic version for doing the routing lookup.

Reviewed by:	kmacy
2009-06-09 09:50:43 +00:00
hrs
998ac729b4 Style fix.
Submitted by:	bz
2009-06-09 08:09:30 +00:00
hrs
d14474a66c - Fix sanity check of GIFSOPTS ioctl.
- Rename option mask s/GIF_FULLOPTS/GIF_OPTMASK/

Spotted by:	Eygene Ryabinkin, delphij
2009-06-09 02:27:59 +00:00
bz
3513417bbf Remove two unneeded, hidden includes. 2009-06-08 20:04:46 +00:00
bz
b7ff2bdc20 After r193232 rt_tables in vnet.h are no longer indirectly dependent on
the ROUTETABLES kernel option thus there is no need to include opt_route.h
anymore in all consumers of vnet.h and no longer depend on it for module
builds.

Remove the hidden include in flowtable.h as well and leave the two
explicit #includes in ip_input.c and ip_output.c.
2009-06-08 19:57:35 +00:00
zec
8b1f38241a Introduce an infrastructure for dismantling vnet instances.
Vnet modules and protocol domains may now register destructor
functions to clean up and release per-module state.  The destructor
mechanisms can be triggered by invoking "vimage -d", or a future
equivalent command which will be provided via the new jail framework.

While this patch introduces numerous placeholder destructor functions,
many of those are currently incomplete, thus leaking memory or (even
worse) failing to stop all running timers.  Many of such issues are
already known and will be incrementaly fixed over the next weeks in
smaller incremental commits.

Apart from introducing new fields in structs ifnet, domain, protosw
and vnet_net, which requires the kernel and modules to be rebuilt, this
change should have no impact on nooptions VIMAGE builds, since vnet
destructors can only be called in VIMAGE kernels.  Moreover,
destructor functions should be in general compiled in only in
options VIMAGE builds, except for kernel modules which can be safely
kldunloaded at run time.

Bump __FreeBSD_version to 800097.
Reviewed by:	bz, julian
Approved by:	rwatson, kib (re), julian (mentor)
2009-06-08 17:15:40 +00:00
hrs
9bf362d0cc Fix and add a workaround on an issue of EtherIP packet with reversed
version field sent via gif(4)+if_bridge(4).  The EtherIP
implementation found on FreeBSD 6.1, 6.2, 6.3, 7.0, 7.1, and 7.2 had
an interoperability issue because it sent the incorrect EtherIP
packets and discarded the correct ones.

This change introduces the following two flags to gif(4):

 accept_rev_ethip_ver: accepts both correct EtherIP packets and ones
    with reversed version field, if enabled.  If disabled, the gif
    accepts the correct packets only.  This flag is enabled by
    default.

 send_rev_ethip_ver: sends EtherIP packets with reversed version field
    intentionally, if enabled.  If disabled, the gif sends the correct
    packets only.  This flag is disabled by default.

These flags are stored in struct gif_softc and can be set by
ifconfig(8) on per-interface basis.

Note that this is an incompatible change of EtherIP with the older
FreeBSD releases.  If you need to interoperate older FreeBSD boxes and
new versions after this commit, setting "send_rev_ethip_ver" is
needed.

Reviewed by:	thompsa and rwatson
Spotted by:	Shunsuke SHINOMIYA
PR:		kern/125003
MFC after:	2 weeks
2009-06-07 23:00:40 +00:00
rwatson
f4934662e5 Move "options MAC" from opt_mac.h to opt_global.h, as it's now in GENERIC
and used in a large number of files, but also because an increasing number
of incorrect uses of MAC calls were sneaking in due to copy-and-paste of
MAC-aware code without the associated opt_mac.h include.

Discussed with:	pjd
2009-06-05 14:55:22 +00:00
luigi
1384b62c4b More cleanup in preparation of ipfw relocation (no actual code change):
+ move ipfw and dummynet hooks declarations to raw_ip.c (definitions
  in ip_var.h) same as for most other global variables.
  This removes some dependencies from ip_input.c;

+ remove the IPFW_LOADED macro, just test ip_fw_chk_ptr directly;

+ remove the DUMMYNET_LOADED macro, just test ip_dn_io_ptr directly;

+ move ip_dn_ruledel_ptr to ip_fw2.c which is the only file using it;

To be merged together with rev 193497

MFC after:	5 days
2009-06-05 13:44:30 +00:00
sam
ba34647600 move ifq_detach from if_detach to if_free; this permits callers to
reference if_snd in the period between detach+free which helps simplify
detach code

Reviewed by:	jhb, rwatson
2009-06-02 18:53:21 +00:00
rwatson
5984810c66 Revert a recent netisr2 change: when billing packets to the current
CPU, don't lock the workstream, as its mutexes may not have been
initialized if there are fewer workstreams than CPUs.

Run into by:	hps, ps
2009-06-01 18:38:36 +00:00
bz
c62e99f85d Convert the two dimensional array to be malloced and introduce
an accessor function to get the correct rnh pointer back.

Update netstat to get the correct pointer using kvm_read()
as well.

This not only fixes the ABI problem depending on the kernel
option but also permits the tunable to overwrite the kernel
option at boot time up to MAXFIBS, enlarging the number of
FIBs without having to recompile. So people could just use
GENERIC now.

Reviewed by:	julian, rwatson, zec
X-MFC:		not possible
2009-06-01 15:49:42 +00:00
rwatson
d07d0043a3 Garbage collect NETISR_POLL and NETISR_POLLMORE, which are no longer
required for options DEVICE_POLLING.

De-fragment the NETISR_ constant space and lower NETISR_MAXPROT from
32 to 16 -- when sizing queue arrays using this compile-time constant,
significant amounts of memory are saved.

Warn on the console when tunable values for netisr are automatically
adjusted during boot due to exceeding limits, invalid values, or as a
result of DEVICE_POLLING.
2009-06-01 15:03:58 +00:00
rwatson
2bab695560 Reimplement the netisr framework in order to support parallel netisr
threads:

- Support up to one netisr thread per CPU, each processings its own
  workstream, or set of per-protocol queues.  Threads may be bound
  to specific CPUs, or allowed to migrate, based on a global policy.

  In the future it would be desirable to support topology-centric
  policies, such as "one netisr per package".

- Allow each protocol to advertise an ordering policy, which can
  currently be one of:

  NETISR_POLICY_SOURCE: packets must maintain ordering with respect to
    an implicit or explicit source (such as an interface or socket).

  NETISR_POLICY_FLOW: make use of mbuf flow identifiers to place work,
    as well as allowing protocols to provide a flow generation function
    for mbufs without flow identifers (m2flow).  Falls back on
    NETISR_POLICY_SOURCE if now flow ID is available.

  NETISR_POLICY_CPU: allow protocols to inspect and assign a CPU for
    each packet handled by netisr (m2cpuid).

- Provide utility functions for querying the number of workstreams
  being used, as well as a mapping function from workstream to CPU ID,
  which protocols may use in work placement decisions.

- Add explicit interfaces to get and set per-protocol queue limits, and
  get and clear drop counters, which query data or apply changes across
  all workstreams.

- Add a more extensible netisr registration interface, in which
  protocols declare 'struct netisr_handler' structures for each
  registered NETISR_ type.  These include name, handler function,
  optional mbuf to flow ID function, optional mbuf to CPU ID function,
  queue limit, and ordering policy.  Padding is present to allow these
  to be expanded in the future.  If no queue limit is declared, then
  a default is used.

- Queue limits are now per-workstream, and raised from the previous
  IFQ_MAXLEN default of 50 to 256.

- All protocols are updated to use the new registration interface, and
  with the exception of netnatm, default queue limits.  Most protocols
  register as NETISR_POLICY_SOURCE, except IPv4 and IPv6, which use
  NETISR_POLICY_FLOW, and will therefore take advantage of driver-
  generated flow IDs if present.

- Formalize a non-packet based interface between interface polling and
  the netisr, rather than having polling pretend to be two protocols.
  Provide two explicit hooks in the netisr worker for start and end
  events for runs: netisr_poll() and netisr_pollmore(), as well as a
  function, netisr_sched_poll(), to allow the polling code to schedule
  netisr execution.  DEVICE_POLLING still embeds single-netisr
  assumptions in its implementation, so for now if it is compiled into
  the kernel, a single and un-bound netisr thread is enforced
  regardless of tunable configuration.

In the default configuration, the new netisr implementation maintains
the same basic assumptions as the previous implementation: a single,
un-bound worker thread processes all deferred work, and direct dispatch
is enabled by default wherever possible.

Performance measurement shows a marginal performance improvement over
the old implementation due to the use of batched dequeue.

An rmlock is used to synchronize use and registration/unregistration
using the framework; currently, synchronized use is disabled
(replicating current netisr policy) due to a measurable 3%-6% hit in
ping-pong micro-benchmarking.  It will be enabled once further rmlock
optimization has taken place.  However, in practice, netisrs are
rarely registered or unregistered at runtime.

A new man page for netisr will follow, but since one doesn't currently
exist, it hasn't been updated.

This change is not appropriate for MFC, although the polling shutdown
handler should be merged to 7-STABLE.

Bump __FreeBSD_version.

Reviewed by:	bz
2009-06-01 10:41:38 +00:00
zec
861b77b017 Introduce an interm userland-kernel API for creating vnets and
assigning ifnets from one vnet to another.  Deletion of vnets is not
yet supported.

The interface is implemented as an ioctl extension so that no syscalls
had to be introduced.  This should be acceptable given that the new
interface will be used for a short / interim period only, until the
new jail management framwork gains the capability of managing vnets.
This method for managing vimages / vnets has been in use for the past
7 years without any observable issues.

The userland tool to be used in conjunction with the interim API can be
found in p4: //depot/projects/vimage-commit2/src/usr.sbin/vimage/... and
will most probably never get commited to svn.

While here, bump copyright notices in kern_vimage.c and vimage.h to
cover work done in year 2009.

Approved by:	julian (mentor)
Discussed with:	bz, rwatson
2009-05-31 12:10:04 +00:00
attilio
b523608331 When user_frac in the polling subsystem is low it is going to busy the
CPU for too long period than necessary.  Additively, interfaces are kept
polled (in the tick) even if no more packets are available.
In order to avoid such situations a new generic mechanism can be
implemented in proactive way, keeping track of the time spent on any
packet and fragmenting the time for any tick, stopping the processing
as soon as possible.

In order to implement such mechanism, the polling handler needs to
change, returning the number of packets processed.
While the intended logic is not part of this patch, the polling KPI is
broken by this commit, adding an int return value and the new flag
IFCAP_POLLING_NOCOUNT (which will signal that the return value is
meaningless for the installed handler and checking should be skipped).

Bump __FreeBSD_version in order to signal such situation.

Reviewed by:	emaste
Sponsored by:	Sandvine Incorporated
2009-05-30 15:14:44 +00:00
rwatson
52ba259960 Make the rmlock(9) interface a bit more like the rwlock(9) interface:
- Add rm_init_flags() and accept extended options only for that variation.
- Add a flags space specifically for rm_init_flags(), rather than borrowing
  the lock_init() flag space.
- Define flag RM_RECURSE to use instead of LO_RECURSABLE.
- Define flag RM_NOWITNESS to allow an rmlock to be exempt from WITNESS
  checking; this wasn't possible previously as rm_init() always passed
  LO_WITNESS when initializing an rmlock's struct lock.
- Add RM_SYSINIT_FLAGS().
- Rename embedded mutex in rmlocks to make it more obvious what it is.
- Update consumers.
- Update man page.
2009-05-29 10:52:37 +00:00
jamie
a013e0afcb Add hierarchical jails. A jail may further virtualize its environment
by creating a child jail, which is visible to that jail and to any
parent jails.  Child jails may be restricted more than their parents,
but never less.  Jail names reflect this hierarchy, being MIB-style
dot-separated strings.

Every thread now points to a jail, the default being prison0, which
contains information about the physical system.  Prison0's root
directory is the same as rootvnode; its hostname is the same as the
global hostname, and its securelevel replaces the global securelevel.
Note that the variable "securelevel" has actually gone away, which
should not cause any problems for code that properly uses
securelevel_gt() and securelevel_ge().

Some jail-related permissions that were kept in global variables and
set via sysctls are now per-jail settings.  The sysctls still exist for
backward compatibility, used only by the now-deprecated jail(2) system
call.

Approved by:	bz (mentor)
2009-05-27 14:11:23 +00:00
sam
4578aab134 rev bpf attach/detach event api to include the dlt 2009-05-25 16:34:35 +00:00
zec
48f748dc29 V_irtualize the if_clone framework, thus allowing for clonable ifnets
to optionally have overlapping unit numbers if attached in different
vnets.

At this stage if_loop is the only clonable ifnet class that has been
extended to allow for such overlapping allocation of unit numbers, i.e.
in each vnet it is possible to have a lo0 interface.  Other clonable ifnet
classes remain to operate with traditional semantics, i.e. each instance
of a clonable ifnet will be assigned a globally unique unit number,
regardless in which vnet such an ifnet becomes instantiated.

While here, garbage collect unused _lo_list field in struct vnet_net,
as well as improve indentation for #defines in sys/net/vnet.h.

The layout of struct vnet_net has changed, therefore bump
__FreeBSD_version.

This change has no functional impact on nooptions VIMAGE kernel builds.

Reviewed by:	bz, brooks
Approved by:	julian (mentor)
2009-05-23 21:43:44 +00:00
zec
ce69980b94 Set ifp->if_afdata_initialized to 0 while holding IF_AFDATA_LOCK on ifp,
not after the lock has been released.

Reviewed by:	bz
Discussed with:	rwatson
2009-05-22 22:22:21 +00:00
zec
363a644ce6 Introduce the if_vmove() function, which will be used in the future
for reassigning ifnets from one vnet to another.

if_vmove() works by calling a restricted subset of actions normally
executed by if_detach() on an ifnet in the current vnet, and then
switches to the target vnet and executes an appropriate subset of
if_attach() actions there.

if_attach() and if_detach() have become wrapper functions around
if_attach_internal() and if_detach_internal(), where the later
variants have an additional argument, a flag indicating whether a
full attach or detach sequence is to be executed, or only a
restricted subset suitable for moving an ifnet from one vnet to
another.  Hence, if_vmove() will not call if_detach() and if_attach()
directly, but will call the if_detach_internal() and
if_attach_internal() variants instead, with the vmove flag set.

While here, staticize ifnet_setbyindex() since it is not referenced
from outside of sys/net/if.c.

Also rename ifccnt field in struct vimage to ifcnt, and do some minor
whitespace garbage collection where appropriate.

This change should have no functional impact on nooptions VIMAGE kernel
builds.

Reviewed by:	bz, rwatson, brooks?
Approved by:	julian (mentor)
2009-05-22 22:09:00 +00:00
qingli
e6b86b7c8f When an interface address is removed and the last prefix
route is also being deleted, the link-layer address table
(arp or nd6) will flush those L2 llinfo entries that match
the removed prefix.

Reviewed by:	kmacy
2009-05-20 21:07:15 +00:00
sam
f487a64e06 add bpf_track eventhandler for monitoring bpf taps attached/detached
Reviewed by:	csjp
2009-05-18 17:18:40 +00:00
rwatson
2e8fb1cbcc Garbage collect unused NETISR_{ATM,NETGRAPH,PPP} netisr constants. 2009-05-18 10:33:23 +00:00
rwatson
deae02e77d Garbage collect now-unused NETISR_FORCEQUEUE, which overrode the global
direct dispatch policy for specific protocols (NETISR_USB).  We leave
the additional 'flags' argument to netisr_register() for the time being,
even though it is no longer required.
2009-05-13 17:22:33 +00:00
rwatson
e0965aca60 Remove now-unused NETISR_USB. 2009-05-13 17:17:05 +00:00
zec
d78a1b1a82 Change the curvnet variable from a global const struct vnet *,
previously always pointing to the default vnet context, to a
dynamically changing thread-local one.  The currvnet context
should be set on entry to networking code via CURVNET_SET() macros,
and reverted to previous state via CURVNET_RESTORE().  Recursions
on curvnet are permitted, though strongly discuouraged.

This change should have no functional impact on nooptions VIMAGE
kernel builds, where CURVNET_* macros expand to whitespace.

The curthread->td_vnet (aka curvnet) variable's purpose is to be an
indicator of the vnet context in which the current network-related
operation takes place, in case we cannot deduce the current vnet
context from any other source, such as by looking at mbuf's
m->m_pkthdr.rcvif->if_vnet, sockets's so->so_vnet etc.  Moreover, so
far curvnet has turned out to be an invaluable consistency checking
aid: it helps to catch cases when sockets, ifnets or any other
vnet-aware structures may have leaked from one vnet to another.

The exact placement of the CURVNET_SET() / CURVNET_RESTORE() macros
was a result of an empirical iterative process, whith an aim to
reduce recursions on CURVNET_SET() to a minimum, while still reducing
the scope of CURVNET_SET() to networking only operations - the
alternative would be calling CURVNET_SET() on each system call entry.
In general, curvnet has to be set in three typicall cases: when
processing socket-related requests from userspace or from within the
kernel; when processing inbound traffic flowing from device drivers
to upper layers of the networking stack, and when executing
timer-driven networking functions.

This change also introduces a DDB subcommand to show the list of all
vnet instances.

Approved by:	julian (mentor)
2009-05-05 10:56:12 +00:00
zec
7a56f17240 Make indentation more uniform accross vnet container structs.
This is a purely cosmetic / NOP change.

Reviewed by:	bz
Approved by:	julian (mentor)
Verified by:	svn diff -x -w producing no output
2009-05-02 08:16:26 +00:00
zec
d4df3d2519 Unbreak options VIMAGE + nooptions INVARIANTS kernel builds.
Submitted by:	julian
Approved by:	julian (mentor)
2009-05-02 05:02:28 +00:00
thompsa
e3d44e50bf Reorder the bridge add and delete routines to avoid calling ifpromisc() with
the bridge lock held.
2009-05-01 19:46:42 +00:00
thompsa
f55b83f9f4 Use the flowid if its available for selecting the tx port. 2009-04-30 14:25:44 +00:00
zec
39b6dc8ba2 Permit buiding kernels with options VIMAGE, restricted to only a single
active network stack instance.  Turning on options VIMAGE at compile
time yields the following changes relative to default kernel build:

1) V_ accessor macros for virtualized variables resolve to structure
fields via base pointers, instead of being resolved as fields in global
structs or plain global variables.  As an example, V_ifnet becomes:

    options VIMAGE:          ((struct vnet_net *) vnet_net)->_ifnet
    default build:           vnet_net_0._ifnet
    options VIMAGE_GLOBALS:  ifnet

2) INIT_VNET_* macros will declare and set up base pointers to be used
by V_ accessor macros, instead of resolving to whitespace:

    INIT_VNET_NET(ifp->if_vnet); becomes

    struct vnet_net *vnet_net = (ifp->if_vnet)->mod_data[VNET_MOD_NET];

3) Memory for vnet modules registered via vnet_mod_register() is now
allocated at run time in sys/kern/kern_vimage.c, instead of per vnet
module structs being declared as globals.  If required, vnet modules
can now request the framework to provide them with allocated bzeroed
memory by filling in the vmi_size field in their vmi_modinfo structures.

4) structs socket, ifnet, inpcbinfo, tcpcb and syncache_head are
extended to hold a pointer to the parent vnet.  options VIMAGE builds
will fill in those fields as required.

5) curvnet is introduced as a new global variable in options VIMAGE
builds, always pointing to the default and only struct vnet.

6) struct sysctl_oid has been extended with additional two fields to
store major and minor virtualization module identifiers, oid_v_subs and
oid_v_mod.  SYSCTL_V_* family of macros will fill in those fields
accordingly, and store the offset in the appropriate vnet container
struct in oid_arg1.
In sysctl handlers dealing with virtualized sysctls, the
SYSCTL_RESOLVE_V_ARG1() macro will compute the address of the target
variable and make it available in arg1 variable for further processing.

Unused fields in structs vnet_inet, vnet_inet6 and vnet_ipfw have
been deleted.

Reviewed by:	bz, rwatson
Approved by:	julian (mentor)
2009-04-30 13:36:26 +00:00
kmacy
fe88b83c9d replace IFQ_ENQUEUE + if_start with if_transmit 2009-04-27 22:46:26 +00:00
kmacy
cbd8310535 replace IFQ_HANDOFF with if_transmit 2009-04-27 22:45:56 +00:00
kmacy
e4f2f98bb3 remove gratuitous memory barrier, a remnant of unified L2 / L3 2009-04-27 22:45:19 +00:00
kmacy
25ccf1bf5d remove call to IFQ_HANDOFF is it called by if_transmit in the default case
and doing so allows the ifnet driver to define its own queueing mechanism
2009-04-27 22:44:26 +00:00
sam
6079771a5e use if_transmit intead of direct frobbing of the if_snd q; this is no
longer allowed

Identified by:	rwatson
Reviewed by:	kmacy
2009-04-27 22:06:49 +00:00
zec
8d976eab5c In preparation for turning on options VIMAGE in next commits,
rearrange / replace / adjust several INIT_VNET_* initializer
macros, all of which currently resolve to whitespace.

Reviewed by:	bz (an older version of the patch)
Approved by:	julian (mentor)
2009-04-26 22:06:42 +00:00
rwatson
00b3a1fd4f As with ifnet_byindex_ref(), don't return IFF_DYING interfaces from
ifunit_ref().  ifunit() continues to return them.

MFC after:	3 weeks
2009-04-23 15:56:01 +00:00
rwatson
471539dc8f Add ifunit_ref(), a version of ifunit(), that returns not just an
interface pointer, but also a reference to it.

Modify ifioctl() to use ifunit_ref(), holding the reference until
all ioctls, etc, have completed.

This closes a class of reader-writer races in which interfaces
could be removed during long-running ioctls, leading to crashes.
Many other consumers of ifunit() should now use ifunit_ref() to
avoid similar races.

MFC after:	3 weeks
2009-04-23 13:08:47 +00:00
rwatson
ccc05d4c7f During if_detach(), invoke if_dead() to set the ifnet's function
pointers to "dead" implementations that no-op rather than invoking
the device driver.  This would generally be unexpected and
possibly quite badly handled by most device drivers after
if_detach() has completed.

Reviewed by:	bms
MFC after:	3 weeks
2009-04-23 11:51:53 +00:00
rwatson
bf5b2167ac Move portions of data structure initialization from if_attach() to
if_alloc(), and portions of data structure destruction from if_detach()
to if_free().  These changes leave more of the struct ifnet in a
safe-to-access condition between alloc and attach, and between detach
and free, and focus on attach/detach as stack usage events rather than
data structure initialization.

Affected fields include the linkstate task queue, if_afdata lock,
address lists, kqueue state, and MAC labels.  ifq_attach() ifq_detach()
are not moved as ifq_attach() may use a queue length set by the device
driver between if_alloc() and if_attach().

MFC after:	3 weeks
2009-04-23 10:59:40 +00:00
rwatson
c797841f0d Add a new interface flag, IFF_DYING, which is set when a device driver
calls if_free(), and remains set if the refcount is elevated.  IF_DYING
skips the bit in the if_flags bitmask previously used by IFF_NEEDSGIANT,
so that an MFC can be done without changing which bit is used, as
IFF_NEEDSGIANT is still present in 7.x.

ifnet_byindex_ref() checks for IFF_DYING and returns NULL if it is set,
preventing new references from by acquired by index, preventing
monitoring sysctls from seeing it.  Other lookup mechanisms currently
do not check IFF_DYING, but may need to in the future.

MFC after:	3 weeks
2009-04-23 09:32:30 +00:00
rwatson
6b19bec016 Start to address a number of races relating to use of ifnet pointers
after the corresponding interface has been destroyed:

(1) Add an ifnet refcount, ifp->if_refcount.  Initialize it to 1 in
    if_alloc(), and modify if_free_type() to decrement and check the
    refcount.

(2) Add new if_ref() and if_rele() interfaces to allow kernel code
    walking global interface lists to release IFNET_[RW]LOCK() yet
    keep the ifnet stable.  Currently, if_rele() is a no-op wrapper
    around if_free(), but this may change in the future.

(3) Add new ifnet field, if_alloctype, which caches the type passed
    to if_alloc(), but unlike if_type, won't be changed by drivers.
    This allows asynchronous free's of the interface after the
    driver has released it to still use the right type.  Use that
    instead of the type passed to if_free_type(), but assert that
    they are the same (might have to rethink this if that doesn't
    work out).

(4) Add a new ifnet_byindex_ref(), which looks up an interface by
    index and returns a reference rather than a pointer to it.

(5) Fix if_alloc() to fully initialize the if_addr_mtx before hooking
    up the ifnet to global lists.

(6) Modify sysctls in if_mib.c to use ifnet_byindex_ref() and release
    the ifnet when done.

When this change is MFC'd, it will need to replace if_ispare fields
rather than adding new fields in order to avoid breaking the binary
interface.  Once this change is MFC'd, if_free_type() should be
removed, as its 'type' argument is now optional.

This refcount is not appropriate for counting mbuf pkthdr references,
and also not for counting entry into the device driver via ifnet
function pointers.  An rmlock may be appropriate for the latter.
Rather, this is about ensuring data structure stability when reaching
an ifnet via global ifnet lists and tables followed by copy in or out
of userspace.

MFC after:      3 weeks
Reported by:    mdtancsa
Reviewed by:    brooks
2009-04-21 22:43:32 +00:00