from x86 to use smp_ipi_mtx spin lock not only for smp_rendezvous_cpus()
but also for the MD cache invalidation, TLB demapping and remote register
reading IPIs due to the following reasons:
- The cross-IPI SMP deadlock x86 otherwise is subject to can't happen on
sparc64. That's because on sparc64, spin locks don't disable interrupts
completely but only raise the processor interrupt level to PIL_TICK. This
means that IPIs still get delivered and direct dispatch IPIs such as the
cache invalidation etc. IPIs in question are still executed.
- In smp_rendezvous_cpus(), smp_ipi_mtx is held not only while sending an
IPI_RENDEZVOUS, but until all CPUs have processed smp_rendezvous_action().
Consequently, smp_ipi_mtx may be locked for an extended amount of time as
queued IPIs (as opposed to the direct ones) such as IPI_RENDEZVOUS are
scheduled via a soft interrupt. Moreover, given that this soft interrupt
is only delivered at PIL_RENDEZVOUS, processing of smp_rendezvous_action()
on a target may be interrupted by f. e. a tick interrupt at PIL_TICK, in
turn leading to the target in question trying to send an IPI by itself
while IPI_RENDEZVOUS isn't fully handled, yet, and, thus, resulting in a
deadlock.
o As mentioned in the commit message of r245850, on least some sun4u platforms
concurrent sending of IPIs by different CPUs is fatal. Therefore, hold the
reintroduced MD ipi_mtx also while delivering cross-traps via MI helpers,
i. e. ipi_{all_but_self,cpu,selected}().
o Akin to x86, let the last CPU to process cpu_mp_bootstrap() set smp_started
instead of the BSP in cpu_mp_unleash(). This ensures that all APs actually
are started, when smp_started is no longer 0.
o In all MD and MI IPI helpers, check for smp_started == 1 rather than for
smp_cpus > 1 or nothing at all. This avoids races during boot causing IPIs
trying to be delivered to APs that in fact aren't up and running, yet.
While at it, move setting of the cpu_ipi_{selected,single}() pointers to
the appropriate delivery functions from mp_init() to cpu_mp_start() where
it's better suited and allows to get rid of the global isjbus variable.
o Given that now concurrent IPI delivery no longer is possible, also nuke
the delays before completely disabling interrupts again in the CPU-specific
cross-trap delivery functions, previously giving other CPUs a window for
sending IPIs on their part. Actually, we now should be able to entirely get
rid of completely disabling interrupts in these functions. Such a change
needs more testing, though.
o In {s,}tick_get_timecount_mp(), make the {s,}tick variable static. While not
necessary for correctness, this avoids page faults when accessing the stack
of a foreign CPU as {s,}tick now is locked into the TLBs as part of static
kernel data. Hence, {s,}tick_get_timecount_mp() always execute as fast as
possible, avoiding jitter.
PR: 201245
MFC after: 3 days
The number of available lock list entries for a thread is LOCK_CHILDCOUNT,
and each entry can record up to LOCK_NCHILDREN locks. When iterating over
the locks held by a thread, a bound on the loop index is therefore given
by LOCK_CHILDCOUNT * LOCK_NCHILDREN; WITNESS_COUNT is an unrelated
constant.
Reviewed by: jhb
MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D2974
Lock order checking is done without the witness mutex held, so multiple
threads that are racing to establish a new lock order may read matrix
entries that are in an inconsistent state. Don't print a warning in this
case, but instead just redo the check after taking the witness lock.
Differential Revision: https://reviews.freebsd.org/D2713
Reviewed by: jhb
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division
The replacement started at r283088 was necessarily incomplete without
replacing boolean_t with bool. This also involved cleaning some type
mismatches and ansifying old C function declarations.
Pointed out by: bde
Discussed with: bde, ian, jhb
currently a spin lock. Apparently, the only reason for this is that
umtx_thread_exit() is called under the process spinlock, which put the
requirement on the umtx_lock. Note that the witness static order list
is wrong for the umtx_lock, umtx_lock is explicitely before any thread
lock, so it is also before sleepq locks.
Change umtx_lock to be the sleepable mutex. For the reason above, the
calls to umtx_thread_exit() are moved from thread_exit() earlier in
each caller, when the process spin lock is not yet taken.
Discussed with: jhb
Tested by: pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
1. Remove initializer for badstack_sbuf_size; it gets set unconditionally.
2. Remove meaningless comment.
3. Group witness_count and its sysctl together.
4. Fix spacing in for statements (space after for and within condition).
5. Change *all* M_NOWAIT usages in witness_initialize() to M_WAITOK; not
just those that were newly introduced -- the allocation is assumed to
succeed for all allocations.
6. Avoid using uint8_t as the base type in sizeof() expressions; Use the
variable name (w_rmatrix) as much as possible.
Pointed out by: jhb@ (thanks!)
the value without recompiling the kernel. This is useful when
recompiling is not possible as an immediate solution. When we run out
of witness objects, witness is completely disabled. Not having an
immediate solution can therefore be problematic.
Submitted by: Sreekanth Rupavatharam <rupavath@juniper.net>
Obtained from: Juniper Networks, Inc.
This includes:
o All directories named *ia64*
o All files named *ia64*
o All ia64-specific code guarded by __ia64__
o All ia64-specific makefile logic
o Mention of ia64 in comments and documentation
This excludes:
o Everything under contrib/
o Everything under crypto/
o sys/xen/interface
o sys/sys/elf_common.h
Discussed at: BSDcan
These changes prevent sysctl(8) from returning proper output,
such as:
1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.
Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.
MFC after: 2 weeks
Sponsored by: Mellanox Technologies
pmap pvlist locks which are scaled by MAXCPU.
This allows an amd64 system to boot with MAXCPU set
to 256, which is currently FreeBSD's hard limit without
x2apic support.
Compile-tested for other arch's.
PR: 185831
Discussed with: jhb
MFC after: 3 weeks
AppleTalk was a network transport protocol for Apple Macintosh devices
in 80s and then 90s. Starting with Mac OS X in 2000 the AppleTalk was
a legacy protocol and primary networking protocol is TCP/IP. The last
Mac OS X release to support AppleTalk happened in 2009. The same year
routing equipment vendors (namely Cisco) end their support.
Thus, AppleTalk won't be supported in FreeBSD 11.0-RELEASE.
is operational. init_sleepqueues() initializes 256 mutexes, which,
due to witness still being cold, started to overflow the pending_locks
array.
As stated in the reported panic message, increase WITNESS_PENDLIST
from 768 to 1024, which provides space for additional 256 locks.
Reported by: many
Tested by: rakuco, bdrewery
of a lock within a single thread.
- Fix handling of interlocks in WITNESS by properly requiring the interlock
to be held exactly once if it is specified.
locks. To support this, VNODE locks are created with the LK_IS_VNODE
flag. This flag is propagated down using the LO_IS_VNODE flag.
Note that WITNESS still records the LOR. Only the printing and the
optional entering into the kernel debugger is bypassed with the
WITNESS_NO_VNODE option.
This is an ongoing effort to provide runtime debug information
useful in the field that does not panic existing installations.
This gives us the flexibility needed when shipping images to a
potentially large audience with WITNESS enabled without worrying
about formerly non-fatal LORs hurting a release.
Sponsored by: iXsystems
other CPUs doesn't require locking so get rid of it. As the latter is used
for the timecounter on certain machine models, using a spin lock in this
case can lead to a deadlock with the upcoming callout(9) rework.
- Merge r134227/r167250 from x86:
Avoid cross-IPI SMP deadlock by using the smp_ipi_mtx spin lock not only
for smp_rendezvous_cpus() but also for the MD cache invalidation and TLB
demapping IPIs.
- Mark some unused function arguments as such.
MFC after: 1 week
'flags' field is added to the end of bpf_if structure. Currently the only
flag is BPFIF_FLAG_DYING which is set on bpf detach and checked by bpf_attachd()
Problem can be easily triggered on SMP stable/[89] by the following command (sort of):
'while true; do ifconfig vlan222 create vlan 222 vlandev em0 up ; tcpdump -pi vlan222 & ; ifconfig vlan222 destroy ; done'
Fix possible use-after-free when BPF detaches itself from interface, freeing bpf_bif memory,
while interface is still UP and there can be routes via this interface.
Freeing is now delayed till ifnet_departure_event is received via eventhandler(9) api.
Convert bpfd rwlock back to mutex due lack of performance gain (currently checking if packet
matches filter is done without holding bpfd lock and we have to acquire write lock if packet matches)
Approved by: kib(mentor)
MFC in: 4 weeks
Interface locks and descriptor locks are converted from mutex(9) to rwlock(9).
This greately improves performance: in most common case we need to acquire 1
reader lock instead of 2 mutexes.
- Remove filter(descriptor) (reader) lock in bpf_mtap[2]
This was suggested by glebius@. We protect filter by requesting interface
writer lock on filter change.
- Cover struct bpf_if under BPF_INTERNAL define. This permits including bpf.h
without including rwlock stuff. However, this is is temporary solution,
struct bpf_if should be made opaque for any external caller.
Found by: Dmitrij Tejblum <tejblum@yandex-team.ru>
Sponsored by: Yandex LLC
Reviewed by: glebius (previous version)
Reviewed by: silence on -net@
Approved by: (mentor)
MFC after: 3 weeks
Historical behavior of letting other CPUs merily go on is a default for
time being. The new behavior can be switched on via
kern.stop_scheduler_on_panic tunable and sysctl.
Stopping of the CPUs has (at least) the following benefits:
- more of the system state at panic time is preserved intact
- threads and interrupts do not interfere with dumping of the system
state
Only one thread runs uninterrupted after panic if stop_scheduler_on_panic
is set. That thread might call code that is also used in normal context
and that code might use locks to prevent concurrent execution of certain
parts. Those locks might be held by the stopped threads and would never
be released. To work around this issue, it was decided that instead of
explicit checks for panic context, we would rather put those checks
inside the locking primitives.
This change has substantial portions written and re-written by attilio
and kib at various times. Other changes are heavily based on the ideas
and patches submitted by jhb and mdf. bde has provided many insights
into the details and history of the current code.
The new behavior may cause problems for systems that use a USB keyboard
for interfacing with system console. This is because of some unusual
locking patterns in the ukbd code which have to be used because on one
hand ukbd is below syscons, but on the other hand it has to interface
with other usb code that uses regular mutexes/Giant for its concurrency
protection. Dumping to USB-connected disks may also be affected.
PR: amd64/139614 (at least)
In cooperation with: attilio, jhb, kib, mdf
Discussed with: arch@, bde
Tested by: Eugene Grosbein <eugen@grosbein.net>,
gnn,
Steven Hartland <killing@multiplay.co.uk>,
glebius,
Andrew Boyer <aboyer@averesystems.com>
(various versions of the patch)
MFC after: 3 months (or never)
This enables locking consumers to pass their own structures around as const and
be able to assert locks embedded into those structures.
Reviewed by: ed, kib, jhb
The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.
This has been irking me for a while. This causes significant
CPU use on bottlenecked CPUs (eg my older EEEPC w/ an earlier
Celeron CPU and my MIPS24k boards) when they're passing
a lot of traffic.
Since the file/line values are only used for printing, this
should only affect display. It should have no operational
change on the code, besides reducing CPU use.
sbuf_new_for_sysctl(9). This allows using an sbuf with a SYSCTL_OUT
drain for extremely large amounts of data where the caller knows that
appropriate references are held, and sleeping is not an issue.
Inspired by: rwatson
Add a drain function for struct sysctl_req, and use it for a variety
of handlers, some of which had to do awkward things to get a large
enough SBUF_FIXEDLEN buffer.
Note that some sysctl handlers were explicitly outputting a trailing
NUL byte. This behaviour was preserved, though it should not be
necessary.
Reviewed by: phk (original patch)
unexpected things in copyout(9) and so wiring the user buffer is not
sufficient to perform a copyout(9) while holding a random mutex.
Requested by: nwhitehorn
handlers, some of which had to do awkward things to get a large enough
FIXEDLEN buffer.
Note that some sysctl handlers were explicitly outputting a trailing NUL
byte. This behaviour was preserved, though it should not be necessary.
Reviewed by: phk
(TOCONS | TOLOG) mask even when called from DDB points.
That breaks several output, where the most notable is textdump output.
Fix this by having configurable callbacks passed to witness_list_locks()
and witness_display_spinlock() for printing out datas.
Reported by: several broken textdump outputs
Tested by: Giovanni Trematerra
<giovanni dot trematerra at gmail dot com>
MFC after: 7 days
X-MFC: r207922
architecture from page queue lock to a hashed array of page locks
(based on a patch by Jeff Roberson), I've implemented page lock
support in the MI code and have only moved vm_page's hold_count
out from under page queue mutex to page lock. This changes
pmap_extract_and_hold on all pmaps.
Supported by: Bitgravity Inc.
Discussed with: alc, jeffr, and kib
