Commit Graph

359 Commits

Author SHA1 Message Date
Mateusz Guzik
2466d12b09 sx: port over writer starvation prevention measures from rwlock
A constant stream of readers could completely starve writers and this is not
a hypothetical scenario.

The 'poll2_threads' test from the will-it-scale suite reliably starves writers
even with concurrency < 10 threads.

The problem was run into and diagnosed by dillon@backplane.com

There was next to no change in lock contention profile during -j 128 pkg build,
despite an sx lock being at the top.

Tested by:	pho
2018-05-22 07:20:22 +00:00
Matt Macy
06bf2a6aef Add simple preempt safe epoch API
Read locking is over used in the kernel to guarantee liveness. This API makes
it easy to provide livenes guarantees without atomics.

Includes epoch_test kernel module to stress test the API.

Documentation will follow initial use case.

Test case and improvements to preemption handling in response to discussion
with mjg@

Reviewed by:	imp@, shurd@
Approved by:	sbruno@
2018-05-10 17:55:24 +00:00
Konstantin Belousov
ed9e8bc468 Account the size of the vslock-ed memory by the thread.
Assert that all such memory is unwired on return to usermode.

The count of the wired memory will be used to detect the copyout mode.

Tested by:	pho (as part of the larger patch)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2018-03-24 13:51:27 +00:00
Pedro F. Giffuni
df57947f08 spdx: initial adoption of licensing ID tags.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

Initially, only tag files that use BSD 4-Clause "Original" license.

RelNotes:	yes
Differential Revision:	https://reviews.freebsd.org/D13133
2017-11-18 14:26:50 +00:00
Gleb Smirnoff
83c9dea1ba - Remove 'struct vmmeter' from 'struct pcpu', leaving only global vmmeter
in place.  To do per-cpu stats, convert all fields that previously were
  maintained in the vmmeters that sit in pcpus to counter(9).
- Since some vmmeter stats may be touched at very early stages of boot,
  before we have set up UMA and we can do counter_u64_alloc(), provide an
  early counter mechanism:
  o Leave one spare uint64_t in struct pcpu, named pc_early_dummy_counter.
  o Point counter(9) fields of vmmeter to pcpu[0].pc_early_dummy_counter,
    so that at early stages of boot, before counters are allocated we already
    point to a counter that can be safely written to.
  o For sparc64 that required a whole dummy pcpu[MAXCPU] array.

Further related changes:
- Don't include vmmeter.h into pcpu.h.
- vm.stats.vm.v_swappgsout and vm.stats.vm.v_swappgsin changed to 64-bit,
  to match kernel representation.
- struct vmmeter hidden under _KERNEL, and only vmstat(1) is an exclusion.

This is based on benno@'s 4-year old patch:
https://lists.freebsd.org/pipermail/freebsd-arch/2013-July/014471.html

Reviewed by:	kib, gallatin, marius, lidl
Differential Revision:	https://reviews.freebsd.org/D10156
2017-04-17 17:34:47 +00:00
Konstantin Belousov
aca4bb9112 Do not leak mount references for dying threads.
Thread might create a condition for delayed SU cleanup, which creates
a reference to the mount point in td_su, but exit without returning
through userret(), e.g. when terminating due to single-threading or
process exit.  In this case, td_su reference is not dropped and mount
point cannot be freed.

Handle the situation by clearing td_su also in the thread destructor
and in exit1().  softdep_ast_cleanup() has to receive the thread as
argument, since e.g. thread destructor is executed in different
context.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2017-02-25 10:38:18 +00:00
Konstantin Belousov
77d6809483 The assertion re-added in r302614 was triggered when stopping signal
is delivered to vforked child.  Issue is that we avoid stopping such
children in issignal() to not block parents.  But executed AST, which
ignored stops, leaves the child with the signal pending but no AST
pending.

On first exec after vfork(), call signotify() to handle pending
reenabled signals.  Adjust the assert to not check vfork children
until exec.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2016-07-18 10:53:47 +00:00
Konstantin Belousov
8f01bee46b Revive the check, disabled in r197963.
Despite the implication (process has pending signals -> the current
thread marked for AST and has TDF_NEEDSIGCHK set) is not true due to
other thread might manipulate its signal blocking mask, it should still
hold for the single-threaded processes.  Enable check for the condition
for single-threaded case, and replicate it from userret() to ast() as
well, where we check that ast indeed has no signal to deliver.

Note that the check is under DIAGNOSTIC, it is not enabled for INVARIANTS
but !DIAGNOSTIC since it imposes too heavy-weight locking for day-to-day
used debugging kernel.

Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-07-12 03:53:15 +00:00
Konstantin Belousov
4f4c35bb38 Add assert to complement r302328.
AST must not execute with TDF_SBDRY or TDF_SEINTR/TDF_SERESTART thread
flags set, which is asserted in userret(). As the consequence, -1 return
from cursig() must not be possible.

Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2016-07-12 03:52:05 +00:00
Konstantin Belousov
3a1e5dd8e6 Rewrite sigdeferstop(9) and sigallowstop(9) into more flexible
framework allowing to set the suspension policy for the dynamic block.
Extend the currently possible policies of stopping on interruptible
sleeps and ignoring such sleeps by two more: do not suspend at
interruptible sleeps, but interrupt them with either EINTR or ERESTART.

Reviewed by:	jilles
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)
2016-06-26 20:07:24 +00:00
Edward Tomasz Napierala
ae34b6ff96 Add four new RCTL resources - readbps, readiops, writebps and writeiops,
for limiting disk (actually filesystem) IO.

Note that in some cases these limits are not quite precise. It's ok,
as long as it's within some reasonable bounds.

Testing - and review of the code, in particular the VFS and VM parts - is
very welcome.

MFC after:	1 month
Relnotes:	yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D5080
2016-04-07 04:23:25 +00:00
Mateusz Guzik
e94e50af1d racct: perform a lockless check for p_throttled
This reduces proc lock contention.

Reviewed by:	trasz
2015-07-13 22:52:11 +00:00
Mateusz Guzik
4ea6a9a28f Generalised support for copy-on-write structures shared by threads.
Thread credentials are maintained as follows: each thread has a pointer to
creds and a reference on them. The pointer is compared with proc's creds on
userspace<->kernel boundary and updated if needed.

This patch introduces a counter which can be compared instead, so that more
structures can use this scheme without adding more comparisons on the boundary.
2015-06-10 10:43:59 +00:00
Konstantin Belousov
1bc93bb7b9 Currently, softupdate code detects overstepping on the workitems
limits in the code which is deep in the call stack, and owns several
critical system resources, like vnode locks.  Attempt to wait while
the per-mount softupdate thread cleans up the backlog may deadlock,
because the thread might need to lock the same vnode which is owned by
the waiting thread.

Instead of synchronously waiting for the worker, perform the worker'
tickle and pause until the backlog is cleaned, at the safe point
during return from kernel to usermode.  A new ast request to call
softdep_ast_cleanup() is created, the SU code now only checks the size
of queue and schedules ast.

There is no ast delivery for the kernel threads, so they are exempted
from the mechanism, except NFS daemon threads.  NFS server loop
explicitely checks for the request, and informs the schedule_cleanup()
that it is capable of handling the requests by the process P2_AST_SU
flag.  This is needed because nfsd may be the sole cause of the SU
workqueue overflow.  But, to not cause nsfd to spawn additional
threads just because we slow down existing workers, only tickle su
threads, without waiting for the backlog cleanup.

Reviewed by:	jhb, mckusick
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2015-05-27 09:20:42 +00:00
John Baldwin
ed95805e90 Remove support for Xen PV domU kernels. Support for HVM domU kernels
remains.  Xen is planning to phase out support for PV upstream since it
is harder to maintain and has more overhead.  Modern x86 CPUs include
virtualization extensions that support HVM guests instead of PV guests.
In addition, the PV code was i386 only and not as well maintained recently
as the HVM code.
- Remove the i386-only NATIVE option that was used to disable certain
  components for PV kernels.  These components are now standard as they
  are on amd64.
- Remove !XENHVM bits from PV drivers.
- Remove various shims required for XEN (e.g. PT_UPDATES_FLUSH, LOAD_CR3,
  etc.)
- Remove duplicate copy of <xen/features.h>.
- Remove unused, i386-only xenstored.h.

Differential Revision:	https://reviews.freebsd.org/D2362
Reviewed by:	royger
Tested by:	royger (i386/amd64 HVM domU and amd64 PVH dom0)
Relnotes:	yes
2015-04-30 15:48:48 +00:00
Edward Tomasz Napierala
4b5c9cf62f Add kern.racct.enable tunable and RACCT_DISABLED config option.
The point of this is to be able to add RACCT (with RACCT_DISABLED)
to GENERIC, to avoid having to rebuild the kernel to use rctl(8).

Differential Revision:	https://reviews.freebsd.org/D2369
Reviewed by:	kib@
MFC after:	1 month
Relnotes:	yes
Sponsored by:	The FreeBSD Foundation
2015-04-29 10:23:02 +00:00
Konstantin Belousov
18cc2ff047 Revert r263475: TDP_DEVMEMIO no longer needed, since amd64 /dev/kmem
does not access kernel mappings directly.

Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-01-12 08:58:07 +00:00
Konstantin Belousov
52f3c44efe Fix two issues with /dev/mem access on amd64, both causing kernel page
faults.

First, for accesses to direct map region should check for the limit by
which direct map is instantiated.

Second, for accesses to the kernel map, success returned from the
kernacc(9) does not guarantee that consequent attempt to read or write
to the checked address succeed, since other thread might invalidate
the address meantime.  Add a new thread private flag TDP_DEVMEMIO,
which instructs vm_fault() to return error when fault happens on the
MAP_ENTRY_NOFAULT entry, instead of panicing.  The trap handler would
then see a page fault from access, and recover in normal way, making
/dev/mem access safer.

Remove GIANT_REQUIRED from the amd64 memrw(), since it is not needed
and having Giant locked does not solve issues for amd64.

Note that at least the second issue exists on other architectures, and
requires similar patching for md code.

Reported and tested by:	clusteradm (gjb, sbruno)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2014-03-21 14:25:09 +00:00
Robert Watson
4a14441044 Update kernel inclusions of capability.h to use capsicum.h instead; some
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version to decide whether
to include capability.h.

MFC after:	3 weeks
2014-03-16 10:55:57 +00:00
Attilio Rao
e7a9eed7a8 - Assert for not leaking readers rw locks counter on userland return.
- Use a correct spin_cnt for KDTRACE_HOOK case in rw read lock.

Sponsored by:	EMC / Isilon storage division
2013-12-17 13:37:02 +00:00
Attilio Rao
54366c0bd7 - For kernel compiled only with KDTRACE_HOOKS and not any lock debugging
option, unbreak the lock tracing release semantic by embedding
  calls to LOCKSTAT_PROFILE_RELEASE_LOCK() direclty in the inlined
  version of the releasing functions for mutex, rwlock and sxlock.
  Failing to do so skips the lockstat_probe_func invokation for
  unlocking.
- As part of the LOCKSTAT support is inlined in mutex operation, for
  kernel compiled without lock debugging options, potentially every
  consumer must be compiled including opt_kdtrace.h.
  Fix this by moving KDTRACE_HOOKS into opt_global.h and remove the
  dependency by opt_kdtrace.h for all files, as now only KDTRACE_FRAMES
  is linked there and it is only used as a compile-time stub [0].

[0] immediately shows some new bug as DTRACE-derived support for debug
in sfxge is broken and it was never really tested.  As it was not
including correctly opt_kdtrace.h before it was never enabled so it
was kept broken for a while.  Fix this by using a protection stub,
leaving sfxge driver authors the responsibility for fixing it
appropriately [1].

Sponsored by:	EMC / Isilon storage division
Discussed with:	rstone
[0] Reported by:	rstone
[1] Discussed with:	philip
2013-11-25 07:38:45 +00:00
John Baldwin
3cf3b9f097 Partially revert r195702. Deferring stops is now implemented via a set of
calls to toggle TDF_SBDRY rather than passing PBDRY to individual sleep
calls.
- Remove the stop_allowed parameters from cursig() and issignal().
  issignal() checks TDF_SBDRY directly.
- Remove the PBDRY and SLEEPQ_STOP_ON_BDRY flags.
2013-03-18 17:23:58 +00:00
Edward Tomasz Napierala
a8efb53478 When throttling a process to enforce RACCT limits, do not use neither
PBDRY (which simply doesn't make any sense) nor PCATCH (which could
be used by a malicious process to work around the PCPU limit).

Submitted by:	Rudo Tomori
Reviewed by:	kib
2013-03-14 23:25:42 +00:00
John Baldwin
f9379dc411 Replace the TDP_NOSLEEPING flag with a counter so that the
THREAD_NO_SLEEPING() and THREAD_SLEEPING_OK() macros can nest.

Reviewed by:	attilio
2013-03-01 22:03:31 +00:00
John Baldwin
593efaf9f7 Further refine the handling of stop signals in the NFS client. The
changes in r246417 were incomplete as they did not add explicit calls to
sigdeferstop() around all the places that previously passed SBDRY to
_sleep().  In addition, nfs_getcacheblk() could trigger a write RPC from
getblk() resulting in sigdeferstop() recursing.  Rather than manually
deferring stop signals in specific places, change the VFS_*() and VOP_*()
methods to defer stop signals for filesystems which request this behavior
via a new VFCF_SBDRY flag.  Note that this has to be a VFC flag rather than
a MNTK flag so that it works properly with VFS_MOUNT() when the mount is
not yet fully constructed.  For now, only the NFS clients are set this new
flag in VFS_SET().

A few other related changes:
- Add an assertion to ensure that TDF_SBDRY doesn't leak to userland.
- When a lookup request uses VOP_READLINK() to follow a symlink, mark
  the request as being on behalf of the thread performing the lookup
  (cnp_thread) rather than using a NULL thread pointer.  This causes
  NFS to properly handle signals during this VOP on an interruptible
  mount.

PR:		kern/176179
Reported by:	Russell Cattelan (sigdeferstop() recursion)
Reviewed by:	kib
MFC after:	1 month
2013-02-21 19:02:50 +00:00
Attilio Rao
5584e91718 Fixup r240246: hwpmc needs to retain the pinning until ASTs are not
executed. This means past the point where userret() is generally
executed.

Skip the td_pinned check if a callchain tracing is currently happening
and add a more robust check to pmc_capture_user_callchain() in order to
catch td_pinned leak past ast() in hwpmc case.

Reported and tested by:	fabient
MFC after:	1 week
X-MFC:	r240246
2012-10-30 15:10:50 +00:00
Edward Tomasz Napierala
36af98697d Add CPU percentage limit enforcement to RCTL. The resouce name is "pcpu".
It was implemented by Rudolf Tomori during Google Summer of Code 2012.
2012-10-26 16:01:08 +00:00
Konstantin Belousov
9b233e2307 Add a KPI to allow to reserve some amount of space in the numvnodes
counter, without actually allocating the vnodes. The supposed use of
the getnewvnode_reserve(9) is to reclaim enough free vnodes while the
code still does not hold any resources that might be needed during the
reclamation, and to consume the slack later for getnewvnode() calls
made from the innards. After the critical block is finished, the
caller shall free any reserve left, by getnewvnode_drop_reserve(9).

Reviewed by:	avg
Tested by:	pho
MFC after:	1 week
2012-10-14 19:43:37 +00:00
Attilio Rao
16cbf13b53 Move the checks for td_pinned, td_critnest, TDP_NOFAULTING and
TDP_NOSLEEPING leaking from syscallret() to userret() so that also
trap handling is covered. Also, the check on td_locks is not duplicated
between the two functions.

Reported by:	avg
Reviewed by:	kib
MFC after:	1 week
2012-09-08 18:35:15 +00:00
Attilio Rao
fbe18392a1 Move PT_UPDATED_FLUSH() before td_locks check in order to have more
coverage also in the XEN case.

Reviewed by:	kib
MFC after:	1 week
2012-09-08 18:29:53 +00:00
Attilio Rao
324e57150d userret() already checks for td_locks when INVARIANTS is enabled, so
there is no need to check if Giant is acquired after it.

Reviewed by:	kib
MFC after:	1 week
2012-09-08 18:27:11 +00:00
Pawel Jakub Dawidek
effb6326a1 Remove redundant include.
MFC after:	1 month
2012-06-10 20:24:01 +00:00
John Baldwin
88bf5036fc Include the associated wait channel message for context switch ktrace
records.  kdump supports both the old and new messages.

Submitted by:	Andrey Zonov  andrey zonov org
MFC after:	1 week
2012-04-20 15:32:36 +00:00
Fabien Thomas
f5f9340b98 Add software PMC support.
New kernel events can be added at various location for sampling or counting.
This will for example allow easy system profiling whatever the processor is
with known tools like pmcstat(8).

Simultaneous usage of software PMC and hardware PMC is possible, for example
looking at the lock acquire failure, page fault while sampling on
instructions.

Sponsored by: NETASQ
MFC after:	1 month
2012-03-28 20:58:30 +00:00
Konstantin Belousov
24f3dcfe50 Assert that exiting process does not return to usermode.
Reviewed by:	avg, jhb
MFC after:	1 week
2011-10-03 16:58:58 +00:00
Kip Macy
8451d0dd78 In order to maximize the re-usability of kernel code in user space this
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.

Reviewed by:	rwatson
Approved by:	re (bz)
2011-09-16 13:58:51 +00:00
Konstantin Belousov
26ccf4f10f Inline the syscallenter() and syscallret(). This reduces the time measured
by the syscall entry speed microbenchmarks by ~10% on amd64.

Submitted by:	jhb
Approved by:	re (bz)
MFC after:	2 weeks
2011-09-11 16:05:09 +00:00
Jonathan Anderson
24c1c3bf71 We may split today's CAPABILITIES into CAPABILITY_MODE (which has
to do with global namespaces) and CAPABILITIES (which has to do with
constraining file descriptors). Just in case, and because it's a better
name anyway, let's move CAPABILITIES out of the way.

Also, change opt_capabilities.h to opt_capsicum.h; for now, this will
only hold CAPABILITY_MODE, but it will probably also hold the new
CAPABILITIES (implying constrained file descriptors) in the future.

Approved by: rwatson
Sponsored by: Google UK Ltd
2011-06-29 13:03:05 +00:00
Robert Watson
fc94e4476b Continue introducing Capsicum capability mode support:
If a system call wasn't listed in capabilities.conf, return ECAPMODE at
syscall entry.

Reviewed by:	anderson
Discussed with:	benl, kris, pjd
Sponsored by:	Google, Inc.
Obtained from:	Capsicum Project
MFC after:	3 months
2011-03-01 13:32:07 +00:00
Bjoern A. Zeeb
bf9ce95bd2 Mfp4 CH=177256:
Catch a set vnet upon return to user space. This usually
  means return paths with CURVNET_RESTORE() missing.

  If VNET_DEBUG is turned on we can even tell the function
  that did the CURVNET_SET() which is really helpful; else
  we print "N/A".

  Sponsored by: The FreeBSD Foundation
  Sponsored by: CK Software GmbH
  Reviewed by:  jhb

MFC after:	11 days
2011-02-14 20:49:37 +00:00
Konstantin Belousov
6fa39a7327 Allow debugger to specify that children of the traced process should be
automatically traced. Extend the ptrace(PL_LWPINFO) to report that child
just forked.

Reviewed by:	davidxu, jhb
MFC after:	2 weeks
2011-01-25 10:59:21 +00:00
Ed Maste
25e45560da Remove extra braces for style(9) (found while cleaning up an old work tree). 2010-09-28 01:36:01 +00:00
Rui Paulo
b3d354c9ce Call the systrace_probe_func() when the error value.
Sponsored by:	The FreeBSD Foundation
2010-08-22 11:30:49 +00:00
John Baldwin
f2a664ac97 Retire td_syscalls now that it is no longer needed. 2010-07-15 20:24:37 +00:00
Konstantin Belousov
34a39b7b1f Obey sv_syscallnames bounds in syscallname().
Reported and tested by:	pho
2010-07-04 18:16:17 +00:00
John Baldwin
fc0de8f0b6 Move prototypes for kern_sigtimedwait() and kern_sigprocmask() to
<sys/syscallsubr.h> where all other kern_<syscall> prototypes live.
2010-06-30 18:03:42 +00:00
Konstantin Belousov
153ac44cf6 Count number of threads that enter and leave dynamically registered
syscalls. On the dynamic syscall deregistration, wait until all
threads leave the syscall code. This somewhat increases the safety
of the loadable modules unloading.

Reviewed by:	jhb
Tested by:	pho
MFC after:	1 month
2010-06-28 18:06:46 +00:00
Konstantin Belousov
699d648aab Remove the support for int13 FPU exception reporting on i386. It is
believed that all 486-class CPUs FreeBSD is capable to run on, either
have no FPU and cannot use external coprocessor, or have FPU on the
package and can use #MF.

Reviewed by:	bde
Tested by:	pho (previous version)
2010-06-23 11:12:58 +00:00
Rui Paulo
f05a947676 Make DTrace syscall provider work again by including opt_kdtrace.h here. 2010-06-17 17:34:45 +00:00
Konstantin Belousov
b2318c2860 Allow to use syscallname(9) outside subr_trap.c.
MFC after:	1 month
2010-05-26 15:39:43 +00:00