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add awge(4)
ipfilter(4): mark as MPSAFE. my testing seems to work fine, and this version was known to work on solaris with no global locking available.
ena(4) became MPSAFe last year
Add bge(4) to the list of drivers that take advantage of NET_MPSAFE
fix various typos, mainly s/trasfering/transferring/ and s/theese/these/.
doc: Update TODO.smpnet to reflect invention of ETHER_F_ALLMULTI.
fix various typos in comments and messages.
doc: more MPSAFE interfaces
Remove ixgbe because both ixg and ixv exist in the list.
update the list of ethernet drivers that have been MPSAFEified.
if_tap was made mpsafe in revision 1.102
Remove references to BRIDGE_IPF, it is now compiled in by default.
BRIDGE_IPF is MP-safe, discussed with ozaki-r@
strip(4) was removed
netsmb is no more
write down some observations about the locking wild west around if_mcast_op()
Merge changes from current as of 20200406
FDDI support has been removed.
Token Ring has been removed.
HIPPI has been removed.
Protecting ec_multi* of ethercom with ec_lock have been finished now.
Add aq(4) and ixl(4) to the MPSAFE component list.
Sync with HEAD
Add another known issue (if_flags)
Add another known issue
Sync with HEAD
Note that kernels with NET_MPSAFE won't work with non-NET_MPSAFE modules. XXX The initial merge of the [pgoyette-compat] branch will NOT address XXX this issue.
Sync with HEAD, resolve a few conflicts
Drop LMC-related entry from TODO.smpnet, and note removal of LMC.
Ssync with HEAD
remove references to isdn
Sync with HEAD Resolve a couple of conflicts (result of the uimin/uimax changes)
Note removal of midway and NATM, and prune the entries from TODO.smpnet.
Retire EtherIP, we have L2TP instead.
Pull up following revision(s) (requested by msaitoh in ticket #950): sys/dev/pci/if_lmc.h: revision 1.25 sys/dev/pci/if_lmc.c: revision 1.65 doc/TODO.smpnet: revision 1.20 Move txintr_setup() stuff from lmc_interrupt() and do it in ifnet_start(). Now we can use bpf_mtap() in the TX path. Not tested.
Add ipsecif(4)
Categorize non MP-safe components into protected and unprotected ones
Sync with HEAD
Move txintr_setup() stuff from lmc_interrupt() and do it in ifnet_start(). Now we can use bpf_mtap() in the TX path. Not tested.
Remove the Econet code. It was part of acorn26, which was removed a month ago.
Mention the limitation of enabling both NET_MPSAFE and ALTQ
Mention IPv6 address selection policy isn't MP-safe yet Though it's not a problem until a policy is set.
Mention ec_multi*
Pull up following revision(s) (requested by ozaki-r in ticket #300): crypto/dist/ipsec-tools/src/setkey/parse.y: 1.19 crypto/dist/ipsec-tools/src/setkey/token.l: 1.20 distrib/sets/lists/tests/mi: 1.754, 1.757, 1.759 doc/TODO.smpnet: 1.12-1.13 sys/net/pfkeyv2.h: 1.32 sys/net/raw_cb.c: 1.23-1.24, 1.28 sys/net/raw_cb.h: 1.28 sys/net/raw_usrreq.c: 1.57-1.58 sys/net/rtsock.c: 1.228-1.229 sys/netinet/in_proto.c: 1.125 sys/netinet/ip_input.c: 1.359-1.361 sys/netinet/tcp_input.c: 1.359-1.360 sys/netinet/tcp_output.c: 1.197 sys/netinet/tcp_var.h: 1.178 sys/netinet6/icmp6.c: 1.213 sys/netinet6/in6_proto.c: 1.119 sys/netinet6/ip6_forward.c: 1.88 sys/netinet6/ip6_input.c: 1.181-1.182 sys/netinet6/ip6_output.c: 1.193 sys/netinet6/ip6protosw.h: 1.26 sys/netipsec/ipsec.c: 1.100-1.122 sys/netipsec/ipsec.h: 1.51-1.61 sys/netipsec/ipsec6.h: 1.18-1.20 sys/netipsec/ipsec_input.c: 1.44-1.51 sys/netipsec/ipsec_netbsd.c: 1.41-1.45 sys/netipsec/ipsec_output.c: 1.49-1.64 sys/netipsec/ipsec_private.h: 1.5 sys/netipsec/key.c: 1.164-1.234 sys/netipsec/key.h: 1.20-1.32 sys/netipsec/key_debug.c: 1.18-1.21 sys/netipsec/key_debug.h: 1.9 sys/netipsec/keydb.h: 1.16-1.20 sys/netipsec/keysock.c: 1.59-1.62 sys/netipsec/keysock.h: 1.10 sys/netipsec/xform.h: 1.9-1.12 sys/netipsec/xform_ah.c: 1.55-1.74 sys/netipsec/xform_esp.c: 1.56-1.72 sys/netipsec/xform_ipcomp.c: 1.39-1.53 sys/netipsec/xform_ipip.c: 1.50-1.54 sys/netipsec/xform_tcp.c: 1.12-1.16 sys/rump/librump/rumpkern/Makefile.rumpkern: 1.170 sys/rump/librump/rumpnet/net_stub.c: 1.27 sys/sys/protosw.h: 1.67-1.68 tests/net/carp/t_basic.sh: 1.7 tests/net/if_gif/t_gif.sh: 1.11 tests/net/if_l2tp/t_l2tp.sh: 1.3 tests/net/ipsec/Makefile: 1.7-1.9 tests/net/ipsec/algorithms.sh: 1.5 tests/net/ipsec/common.sh: 1.4-1.6 tests/net/ipsec/t_ipsec_ah_keys.sh: 1.2 tests/net/ipsec/t_ipsec_esp_keys.sh: 1.2 tests/net/ipsec/t_ipsec_gif.sh: 1.6-1.7 tests/net/ipsec/t_ipsec_l2tp.sh: 1.6-1.7 tests/net/ipsec/t_ipsec_misc.sh: 1.8-1.18 tests/net/ipsec/t_ipsec_sockopt.sh: 1.1-1.2 tests/net/ipsec/t_ipsec_tcp.sh: 1.1-1.2 tests/net/ipsec/t_ipsec_transport.sh: 1.5-1.6 tests/net/ipsec/t_ipsec_tunnel.sh: 1.9 tests/net/ipsec/t_ipsec_tunnel_ipcomp.sh: 1.1-1.2 tests/net/ipsec/t_ipsec_tunnel_odd.sh: 1.3 tests/net/mcast/t_mcast.sh: 1.6 tests/net/net/t_ipaddress.sh: 1.11 tests/net/net_common.sh: 1.20 tests/net/npf/t_npf.sh: 1.3 tests/net/route/t_flags.sh: 1.20 tests/net/route/t_flags6.sh: 1.16 usr.bin/netstat/fast_ipsec.c: 1.22 Do m_pullup before mtod It may fix panicks of some tests on anita/sparc and anita/GuruPlug. --- KNF --- Enable DEBUG for babylon5 --- Apply C99-style struct initialization to xformsw --- Tweak outputs of netstat -s for IPsec - Get rid of "Fast" - Use ipsec and ipsec6 for titles to clarify protocol - Indent outputs of sub protocols Original outputs were organized like this: (Fast) IPsec: IPsec ah: IPsec esp: IPsec ipip: IPsec ipcomp: (Fast) IPsec: IPsec ah: IPsec esp: IPsec ipip: IPsec ipcomp: New outputs are organized like this: ipsec: ah: esp: ipip: ipcomp: ipsec6: ah: esp: ipip: ipcomp: --- Add test cases for IPComp --- Simplify IPSEC_OSTAT macro (NFC) --- KNF; replace leading whitespaces with hard tabs --- Introduce and use SADB_SASTATE_USABLE_P --- KNF --- Add update command for testing Updating an SA (SADB_UPDATE) requires that a process issuing SADB_UPDATE is the same as a process issued SADB_ADD (or SADB_GETSPI). This means that update command must be used with add command in a configuration of setkey. This usage is normally meaningless but useful for testing (and debugging) purposes. --- Add test cases for updating SA/SP The tests require newly-added udpate command of setkey. --- PR/52346: Frank Kardel: Fix checksumming for NAT-T See XXX for improvements. --- Remove codes for PACKET_TAG_IPSEC_IN_CRYPTO_DONE It seems that PACKET_TAG_IPSEC_IN_CRYPTO_DONE is for network adapters that have IPsec accelerators; a driver sets the mtag to a packet when its device has already encrypted the packet. Unfortunately no driver implements such offload features for long years and seems unlikely to implement them soon. (Note that neither FreeBSD nor Linux doesn't have such drivers.) Let's remove related (unused) codes and simplify the IPsec code. --- Fix usages of sadb_msg_errno --- Avoid updating sav directly On SADB_UPDATE a target sav was updated directly, which was unsafe. Instead allocate another sav, copy variables of the old sav to the new one and replace the old one with the new one. --- Simplify; we can assume sav->tdb_xform cannot be NULL while it's valid --- Rename key_alloc* functions (NFC) We shouldn't use the term "alloc" for functions that just look up data and actually don't allocate memory. --- Use explicit_memset to surely zero-clear key_auth and key_enc --- Make sure to clear keys on error paths of key_setsaval --- Add missing KEY_FREESAV --- Make sure a sav is inserted to a sah list after its initialization completes --- Remove unnecessary zero-clearing codes from key_setsaval key_setsaval is now used only for a newly-allocated sav. (It was used to reset variables of an existing sav.) --- Correct wrong assumption of sav->refcnt in key_delsah A sav in a list is basically not to be sav->refcnt == 0. And also KEY_FREESAV assumes sav->refcnt > 0. --- Let key_getsavbyspi take a reference of a returning sav --- Use time_mono_to_wall (NFC) --- Separate sending message routine (NFC) --- Simplify; remove unnecessary zero-clears key_freesaval is used only when a target sav is being destroyed. --- Omit NULL checks for sav->lft_c sav->lft_c can be NULL only when initializing or destroying sav. --- Omit unnecessary NULL checks for sav->sah --- Omit unnecessary check of sav->state key_allocsa_policy picks a sav of either MATURE or DYING so we don't need to check its state again. --- Simplify; omit unnecessary saidx passing - ipsec_nextisr returns a saidx but no caller uses it - key_checkrequest is passed a saidx but it can be gotton by another argument (isr) --- Fix splx isn't called on some error paths --- Fix header size calculation of esp where sav is NULL --- Fix header size calculation of ah in the case sav is NULL This fix was also needed for esp. --- Pass sav directly to opencrypto callback In a callback, use a passed sav as-is by default and look up a sav only if the passed sav is dead. --- Avoid examining freshness of sav on packet processing If a sav list is sorted (by lft_c->sadb_lifetime_addtime) in advance, we don't need to examine each sav and also don't need to delete one on the fly and send up a message. Fortunately every sav lists are sorted as we need. Added key_validate_savlist validates that each sav list is surely sorted (run only if DEBUG because it's not cheap). --- Add test cases for SAs with different SPIs --- Prepare to stop using isr->sav isr is a shared resource and using isr->sav as a temporal storage for each packet processing is racy. And also having a reference from isr to sav makes the lifetime of sav non-deterministic; such a reference is removed when a packet is processed and isr->sav is overwritten by new one. Let's have a sav locally for each packet processing instead of using shared isr->sav. However this change doesn't stop using isr->sav yet because there are some users of isr->sav. isr->sav will be removed after the users find a way to not use isr->sav. --- Fix wrong argument handling --- fix printf format. --- Don't validate sav lists of LARVAL or DEAD states We don't sort the lists so the validation will always fail. Fix PR kern/52405 --- Make sure to sort the list when changing the state by key_sa_chgstate --- Rename key_allocsa_policy to key_lookup_sa_bysaidx --- Separate test files --- Calculate ah_max_authsize on initialization as well as esp_max_ivlen --- Remove m_tag_find(PACKET_TAG_IPSEC_PENDING_TDB) because nobody sets the tag --- Restore a comment removed in previous The comment is valid for the below code. --- Make tests more stable sleep command seems to wait longer than expected on anita so use polling to wait for a state change. --- Add tests that explicitly delete SAs instead of waiting for expirations --- Remove invalid M_AUTHIPDGM check on ESP isr->sav M_AUTHIPDGM flag is set to a mbuf in ah_input_cb. An sav of ESP can have AH authentication as sav->tdb_authalgxform. However, in that case esp_input and esp_input_cb are used to do ESP decryption and AH authentication and M_AUTHIPDGM never be set to a mbuf. So checking M_AUTHIPDGM of a mbuf on isr->sav of ESP is meaningless. --- Look up sav instead of relying on unstable sp->req->sav This code is executed only in an error path so an additional lookup doesn't matter. --- Correct a comment --- Don't release sav if calling crypto_dispatch again --- Remove extra KEY_FREESAV from ipsec_process_done It should be done by the caller. --- Don't bother the case of crp->crp_buf == NULL in callbacks --- Hold a reference to an SP during opencrypto processing An SP has a list of isr (ipsecrequest) that represents a sequence of IPsec encryption/authentication processing. One isr corresponds to one opencrypto processing. The lifetime of an isr follows its SP. We pass an isr to a callback function of opencrypto to continue to a next encryption/authentication processing. However nobody guaranteed that the isr wasn't freed, i.e., its SP wasn't destroyed. In order to avoid such unexpected destruction of isr, hold a reference to its SP during opencrypto processing. --- Don't make SAs expired on tests that delete SAs explicitly --- Fix a debug message --- Dedup error paths (NFC) --- Use pool to allocate tdb_crypto For ESP and AH, we need to allocate an extra variable space in addition to struct tdb_crypto. The fixed size of pool items may be larger than an actual requisite size of a buffer, but still the performance improvement by replacing malloc with pool wins. --- Don't use unstable isr->sav for header size calculations We may need to optimize to not look up sav here for users that don't need to know an exact size of headers (e.g., TCP segmemt size caclulation). --- Don't use sp->req->sav when handling NAT-T ESP fragmentation In order to do this we need to look up a sav however an additional look-up degrades performance. A sav is later looked up in ipsec4_process_packet so delay the fragmentation check until then to avoid an extra look-up. --- Don't use key_lookup_sp that depends on unstable sp->req->sav It provided a fast look-up of SP. We will provide an alternative method in the future (after basic MP-ification finishes). --- Stop setting isr->sav on looking up sav in key_checkrequest --- Remove ipsecrequest#sav --- Stop setting mtag of PACKET_TAG_IPSEC_IN_DONE because there is no users anymore --- Skip ipsec_spi_*_*_preferred_new_timeout when running on qemu Probably due to PR 43997 --- Add localcount to rump kernels --- Remove unused macro --- Fix key_getcomb_setlifetime The fix adjusts a soft limit to be 80% of a corresponding hard limit. I'm not sure the fix is really correct though, at least the original code is wrong. A passed comb is zero-cleared before calling key_getcomb_setlifetime, so comb->sadb_comb_soft_addtime = comb->sadb_comb_soft_addtime * 80 / 100; is meaningless. --- Provide and apply key_sp_refcnt (NFC) It simplifies further changes. --- Fix indentation Pointed out by knakahara@ --- Use pslist(9) for sptree --- Don't acquire global locks for IPsec if NET_MPSAFE Note that the change is just to make testing easy and IPsec isn't MP-safe yet. --- Let PF_KEY socks hold their own lock instead of softnet_lock Operations on SAD and SPD are executed via PF_KEY socks. The operations include deletions of SAs and SPs that will use synchronization mechanisms such as pserialize_perform to wait for references to SAs and SPs to be released. It is known that using such mechanisms with holding softnet_lock causes a dead lock. We should avoid the situation. --- Make IPsec SPD MP-safe We use localcount(9), not psref(9), to make the sptree and secpolicy (SP) entries MP-safe because SPs need to be referenced over opencrypto processing that executes a callback in a different context. SPs on sockets aren't managed by the sptree and can be destroyed in softint. localcount_drain cannot be used in softint so we delay the destruction of such SPs to a thread context. To do so, a list to manage such SPs is added (key_socksplist) and key_timehandler_spd deletes dead SPs in the list. For more details please read the locking notes in key.c. Proposed on tech-kern@ and tech-net@ --- Fix updating ipsec_used - key_update_used wasn't called in key_api_spddelete2 and key_api_spdflush - key_update_used wasn't called if an SP had been added/deleted but a reply to userland failed --- Fix updating ipsec_used; turn on when SPs on sockets are added --- Add missing IPsec policy checks to icmp6_rip6_input icmp6_rip6_input is quite similar to rip6_input and the same checks exist in rip6_input. --- Add test cases for setsockopt(IP_IPSEC_POLICY) --- Don't use KEY_NEWSP for dummy SP entries By the change KEY_NEWSP is now not called from softint anymore and we can use kmem_zalloc with KM_SLEEP for KEY_NEWSP. --- Comment out unused functions --- Add test cases that there are SPs but no relevant SAs --- Don't allow sav->lft_c to be NULL lft_c of an sav that was created by SADB_GETSPI could be NULL. --- Clean up clunky eval strings - Remove unnecessary \ at EOL - This allows to omit ; too - Remove unnecessary quotes for arguments of atf_set - Don't expand $DEBUG in eval - We expect it's expanded on execution Suggested by kre@ --- Remove unnecessary KEY_FREESAV in an error path sav should be freed (unreferenced) by the caller. --- Use pslist(9) for sahtree --- Use pslist(9) for sah->savtree --- Rename local variable newsah to sah It may not be new. --- MP-ify SAD slightly - Introduce key_sa_mtx and use it for some list operations - Use pserialize for some list iterations --- Introduce KEY_SA_UNREF and replace KEY_FREESAV with it where sav will never be actually freed in the future KEY_SA_UNREF is still key_freesav so no functional change for now. This change reduces diff of further changes. --- Remove out-of-date log output Pointed out by riastradh@ --- Use KDASSERT instead of KASSERT for mutex_ownable Because mutex_ownable is too heavy to run in a fast path even for DIAGNOSTIC + LOCKDEBUG. Suggested by riastradh@ --- Assemble global lists and related locks into cache lines (NFCI) Also rename variable names from *tree to *list because they are just lists, not trees. Suggested by riastradh@ --- Move locking notes --- Update the locking notes - Add locking order - Add locking notes for misc lists such as reglist - Mention pserialize, key_sp_ref and key_sp_unref on SP operations Requested by riastradh@ --- Describe constraints of key_sp_ref and key_sp_unref Requested by riastradh@ --- Hold key_sad.lock on SAVLIST_WRITER_INSERT_TAIL --- Add __read_mostly to key_psz Suggested by riastradh@ --- Tweak wording (pserialize critical section => pserialize read section) Suggested by riastradh@ --- Add missing mutex_exit --- Fix setkey -D -P outputs The outputs were tweaked (by me), but I forgot updating libipsec in my local ATF environment... --- MP-ify SAD (key_sad.sahlist and sah entries) localcount(9) is used to protect key_sad.sahlist and sah entries as well as SPD (and will be used for SAD sav). Please read the locking notes of SAD for more details. --- Introduce key_sa_refcnt and replace sav->refcnt with it (NFC) --- Destroy sav only in the loop for DEAD sav --- Fix KASSERT(solocked(sb->sb_so)) failure in sbappendaddr that is called eventually from key_sendup_mbuf If key_sendup_mbuf isn't passed a socket, the assertion fails. Originally in this case sb->sb_so was softnet_lock and callers held softnet_lock so the assertion was magically satisfied. Now sb->sb_so is key_so_mtx and also softnet_lock isn't always held by callers so the assertion can fail. Fix it by holding key_so_mtx if key_sendup_mbuf isn't passed a socket. Reported by knakahara@ Tested by knakahara@ and ozaki-r@ --- Fix locking notes of SAD --- Fix deadlock between key_sendup_mbuf called from key_acquire and localcount_drain If we call key_sendup_mbuf from key_acquire that is called on packet processing, a deadlock can happen like this: - At key_acquire, a reference to an SP (and an SA) is held - key_sendup_mbuf will try to take key_so_mtx - Some other thread may try to localcount_drain to the SP with holding key_so_mtx in say key_api_spdflush - In this case localcount_drain never return because key_sendup_mbuf that has stuck on key_so_mtx never release a reference to the SP Fix the deadlock by deferring key_sendup_mbuf to the timer (key_timehandler). --- Fix that prev isn't cleared on retry --- Limit the number of mbufs queued for deferred key_sendup_mbuf It's easy to be queued hundreds of mbufs on the list under heavy network load. --- MP-ify SAD (savlist) localcount(9) is used to protect savlist of sah. The basic design is similar to MP-ifications of SPD and SAD sahlist. Please read the locking notes of SAD for more details. --- Simplify ipsec_reinject_ipstack (NFC) --- Add per-CPU rtcache to ipsec_reinject_ipstack It reduces route lookups and also reduces rtcache lock contentions when NET_MPSAFE is enabled. --- Use pool_cache(9) instead of pool(9) for tdb_crypto objects The change improves network throughput especially on multi-core systems. --- Update ipsec(4), opencrypto(9) and vlan(4) are now MP-safe. --- Write known issues on scalability --- Share a global dummy SP between PCBs It's never be changed so it can be pre-allocated and shared safely between PCBs. --- Fix race condition on the rawcb list shared by rtsock and keysock keysock now protects itself by its own mutex, which means that the rawcb list is protected by two different mutexes (keysock's one and softnet_lock for rtsock), of course it's useless. Fix the situation by having a discrete rawcb list for each. --- Use a dedicated mutex for rt_rawcb instead of softnet_lock if NET_MPSAFE --- fix localcount leak in sav. fixed by ozaki-r@n.o. I commit on behalf of him. --- remove unnecessary comment. --- Fix deadlock between pserialize_perform and localcount_drain A typical ussage of localcount_drain looks like this: mutex_enter(&mtx); item = remove_from_list(); pserialize_perform(psz); localcount_drain(&item->localcount, &cv, &mtx); mutex_exit(&mtx); This sequence can cause a deadlock which happens for example on the following situation: - Thread A calls localcount_drain which calls xc_broadcast after releasing a specified mutex - Thread B enters the sequence and calls pserialize_perform with holding the mutex while pserialize_perform also calls xc_broadcast - Thread C (xc_thread) that calls an xcall callback of localcount_drain tries to hold the mutex xc_broadcast of thread B doesn't start until xc_broadcast of thread A finishes, which is a feature of xcall(9). This means that pserialize_perform never complete until xc_broadcast of thread A finishes. On the other hand, thread C that is a callee of xc_broadcast of thread A sticks on the mutex. Finally the threads block each other (A blocks B, B blocks C and C blocks A). A possible fix is to serialize executions of the above sequence by another mutex, but adding another mutex makes the code complex, so fix the deadlock by another way; the fix is to release the mutex before pserialize_perform and instead use a condvar to prevent pserialize_perform from being called simultaneously. Note that the deadlock has happened only if NET_MPSAFE is enabled. --- Add missing ifdef NET_MPSAFE --- Take softnet_lock on pr_input properly if NET_MPSAFE Currently softnet_lock is taken unnecessarily in some cases, e.g., icmp_input and encap4_input from ip_input, or not taken even if needed, e.g., udp_input and tcp_input from ipsec4_common_input_cb. Fix them. NFC if NET_MPSAFE is disabled (default). --- - sanitize key debugging so that we don't print extra newlines or unassociated debugging messages. - remove unused functions and make internal ones static - print information in one line per message --- humanize printing of ip addresses --- cast reduction, NFC. --- Fix typo in comment --- Pull out ipsec_fill_saidx_bymbuf (NFC) --- Don't abuse key_checkrequest just for looking up sav It does more than expected for example key_acquire. --- Fix SP is broken on transport mode isr->saidx was modified accidentally in ipsec_nextisr. Reported by christos@ Helped investigations by christos@ and knakahara@ --- Constify isr at many places (NFC) --- Include socketvar.h for softnet_lock --- Fix buffer length for ipsec_logsastr
Mention NOMPSAFE
add opencrypto(9)'s scalability comment
Write known issues on scalability
Update ipsec(4), opencrypto(9) and vlan(4) are now MP-safe.
Sync with HEAD
Sync with HEAD
file TODO.smpnet was added on branch bouyer-socketcan on 2017-04-21 16:51:16 +0000
Write about bpf's statistic counters
Write about lingering obsolete variables due to kvm(3)
Sync with HEAD
file TODO.smpnet was added on branch pgoyette-localcount on 2017-03-20 06:52:12 +0000
Add ixv(4) to MP-safe component's list.
Add ixg(4)
Tidy up again
Tidy up the lists
Remove multicast stuffs from the list of Non MP-safe components
Add l2tp(4)
Add BRIDGE_IPF
Add many entries
Defer bpf_mtap in Rx interrupt context to softint bpf_mtap of some drivers is still called in hardware interrupt context. We want to run them in softint as well as bpf_mtap of most drivers (see if_percpuq_softint and if_input). To this end, bpf_mtap_softint mechanism is implemented; it defers bpf_mtap processing to a dedicated softint for a target driver. By using the machanism, we can move bpf_mtap processing to softint without changing target drivers much while it adds some overhead on CPU and memory. Once target drivers are changed to softint-based, we should return to normal bpf_mtap. Proposed on tech-kern and tech-net