a device pager (OBJT_DEVICE) object in that it uses fictitious pages to
provide aliases to other memory addresses. The primary difference is that
it uses an sglist(9) to determine the physical addresses for a given offset
into the object instead of invoking the d_mmap() method in a device driver.
Reviewed by: alc
Approved by: re (kensmith)
MFC after: 2 weeks
network stacks, VNET_SYSINIT:
- Add VNET_SYSINIT and VNET_SYSUNINIT macros to declare events that will
occur each time a network stack is instantiated and destroyed. In the
!VIMAGE case, these are simply mapped into regular SYSINIT/SYSUNINIT.
For the VIMAGE case, we instead use SYSINIT's to track their order and
properties on registration, using them for each vnet when created/
destroyed, or immediately on module load for already-started vnets.
- Remove vnet_modinfo mechanism that existed to serve this purpose
previously, as well as its dependency scheme: we now just use the
SYSINIT ordering scheme.
- Implement VNET_DOMAIN_SET() to allow protocol domains to declare that
they want init functions to be called for each virtual network stack
rather than just once at boot, compiling down to DOMAIN_SET() in the
non-VIMAGE case.
- Walk all virtualized kernel subsystems and make use of these instead
of modinfo or DOMAIN_SET() for init/uninit events. In some cases,
convert modular components from using modevent to using sysinit (where
appropriate). In some cases, do minor rejuggling of SYSINIT ordering
to make room for or better manage events.
Portions submitted by: jhb (VNET_SYSINIT), bz (cleanup)
Discussed with: jhb, bz, julian, zec
Reviewed by: bz
Approved by: re (VIMAGE blanket)
non-vrtiualized sysctls so we cannot used one common function.
Add a macro to convert the arg1 in the virtualized case to
vnet.h to not expose the maths to all over the code.
Add a wrapper for the single virtualized call, properly handling
arg1 and call the default implementation from there.
Convert the two over places to use the new macro.
Reviewed by: rwatson
Approved by: re (kib)
portion of the page that was written. Among other problems, this
page might be picked up by pagedaemon, with failed assertion in
vm_pageout_flush() about validity of the page.
Reported and tested by: pho
Approved by: re (kensmith)
MFC after: 3 weeks
unused custom mutex/condvar-based sleep locks with two locks: an
rwlock (for non-sleeping use) and sxlock (for sleeping use). Either
acquired for read is sufficient to stabilize the vnet list, but both
must be acquired for write to modify the list.
Replace previous no-op read locking macros, used in various places
in the stack, with actual locking to prevent race conditions. Callers
must declare when they may perform unbounded sleeps or not when
selecting how to lock.
Refactor vnet sysinits so that the vnet list and locks are initialized
before kernel modules are linked, as the kernel linker will use them
for modules loaded by the boot loader.
Update various consumers of these KPIs based on whether they may sleep
or not.
Reviewed by: bz
Approved by: re (kib)
modules was present, which turns out to be false in some situations.
Back out the assertion.
Reported by: Luiz Otavio O Souza <lists.br at gmail.com>,
Florian Smeets <flo at kasimir.com>
Approved by: re (kensmith) (implicit)
PCATCH, to indicate that thread shall not be stopped upon receipt of
SIGSTOP until it reaches the kernel->usermode boundary.
Also change thread_single(SINGLE_NO_EXIT) to only stop threads at
the user boundary unconditionally.
Tested by: pho
Reviewed by: jhb
Approved by: re (kensmith)
process that still need to be suspended or exited from thread_single
into the new function calc_remaining().
Tested by: pho
Reviewed by: jhb
Approved by: re (kensmith)
(DPCPU), as suggested by Peter Wemm, and implement a new per-virtual
network stack memory allocator. Modify vnet to use the allocator
instead of monolithic global container structures (vinet, ...). This
change solves many binary compatibility problems associated with
VIMAGE, and restores ELF symbols for virtualized global variables.
Each virtualized global variable exists as a "reference copy", and also
once per virtual network stack. Virtualized global variables are
tagged at compile-time, placing the in a special linker set, which is
loaded into a contiguous region of kernel memory. Virtualized global
variables in the base kernel are linked as normal, but those in modules
are copied and relocated to a reserved portion of the kernel's vnet
region with the help of a the kernel linker.
Virtualized global variables exist in per-vnet memory set up when the
network stack instance is created, and are initialized statically from
the reference copy. Run-time access occurs via an accessor macro, which
converts from the current vnet and requested symbol to a per-vnet
address. When "options VIMAGE" is not compiled into the kernel, normal
global ELF symbols will be used instead and indirection is avoided.
This change restores static initialization for network stack global
variables, restores support for non-global symbols and types, eliminates
the need for many subsystem constructors, eliminates large per-subsystem
structures that caused many binary compatibility issues both for
monitoring applications (netstat) and kernel modules, removes the
per-function INIT_VNET_*() macros throughout the stack, eliminates the
need for vnet_symmap ksym(2) munging, and eliminates duplicate
definitions of virtualized globals under VIMAGE_GLOBALS.
Bump __FreeBSD_version and update UPDATING.
Portions submitted by: bz
Reviewed by: bz, zec
Discussed with: gnn, jamie, jeff, jhb, julian, sam
Suggested by: peter
Approved by: re (kensmith)
dependent memory attributes:
Rename vm_cache_mode_t to vm_memattr_t. The new name reflects the
fact that there are machine-dependent memory attributes that have
nothing to do with controlling the cache's behavior.
Introduce vm_object_set_memattr() for setting the default memory
attributes that will be given to an object's pages.
Introduce and use pmap_page_{get,set}_memattr() for getting and
setting a page's machine-dependent memory attributes. Add full
support for these functions on amd64 and i386 and stubs for them on
the other architectures. The function pmap_page_set_memattr() is also
responsible for any other machine-dependent aspects of changing a
page's memory attributes, such as flushing the cache or updating the
direct map. The uses include kmem_alloc_contig(), vm_page_alloc(),
and the device pager:
kmem_alloc_contig() can now be used to allocate kernel memory with
non-default memory attributes on amd64 and i386.
vm_page_alloc() and the device pager will set the memory attributes
for the real or fictitious page according to the object's default
memory attributes.
Update the various pmap functions on amd64 and i386 that map pages to
incorporate each page's memory attributes in the mapping.
Notes: (1) Inherent to this design are safety features that prevent
the specification of inconsistent memory attributes by different
mappings on amd64 and i386. In addition, the device pager provides a
warning when a device driver creates a fictitious page with memory
attributes that are inconsistent with the real page that the
fictitious page is an alias for. (2) Storing the machine-dependent
memory attributes for amd64 and i386 as a dedicated "int" in "struct
md_page" represents a compromise between space efficiency and the ease
of MFCing these changes to RELENG_7.
In collaboration with: jhb
Approved by: re (kib)
correctly checks for reclaimed vnode, possibly calling VOP_REVOKE for
such vnode. If the terminal is already revoked, or devfs mount was
forcibly unmounted, the revocation of doomed ctty vnode causes panic.
Reported and tested by: lstewart
Approved by: re (kensmith)
MFC after: 2 weeks
if the new file mode is the same as it was before; however, this
optimization must be disabled for filesystems that support NFSv4 ACLs.
Chmod uses pathconf(2) to determine whether this is the case - however,
pathconf(2) always follows symbolic links, while the 'chmod -h' doesn't.
This change adds lpathconf(3) to make it possible to solve that problem
in a clean way.
Reviewed by: rwatson (earlier version)
Approved by: re (kib)
As pointed out, POLLHUP should be generated, even if it hasn't been
specified on input. It is also not allowed to return both POLLOUT and
POLLHUP at the same time.
Reported by: jilles
Approved by: re (kib)
under VM environments, it's too slow for FreeBSD to work
properly. For example, ping at 10hz pings about every 600ms
instead of about every second.
Approved by: re (kib)
when all writers, observed by reader, exited. Use writer generation
counter for fifo, and store the snapshot of the fifo generation in the
f_seqcount field of struct file, that is otherwise unused for fifos.
Set FreeBSD-undocumented POLLINIGNEOF flag only when file f_seqcount is
equal to fifo' fi_wgen, and revert r89376.
Fix POLLINIGNEOF for sockets and pipes, and return POLLHUP for them.
Note that the patch does not fix not returning POLLHUP for fifos.
PR: kern/94772
Submitted by: bde (original version)
Reviewed by: rwatson, jilles
Approved by: re (kensmith)
MFC after: 6 weeks (might be)
around the sequence that drop vnode lock and then busies the mount point.
Not having vlocked node or direct reference to the mp allows for the
forced unmount to proceed, making mp unmounted or reused.
Tested by: pho
Reviewed by: jeff
Approved by: re (kensmith)
MFC after: 2 weeks
system calls:
- Centralize generation of argument tokens for VM addresses in a macro,
ADDR_TOKEN(), and properly encode 64-bit addresses in 64-bit arguments.
- Fix up argument numbers across a large number of syscalls so that they
match the numeric argument into the system call.
- Don't audit the address argument to ioctl(2) or ptrace(2), but do keep
generating tokens for mmap(2), minherit(2), since they relate to passing
object access across execve(2).
Approved by: re (audit argument blanket)
Obtained from: TrustedBSD Project
MFC after: 1 week
using the size of the descriptor array.
- A lock is not needed to fetch fd_lastfile. The results are stale the
instant it is dropped.
- Use a private mutex pool for select since the pool mutex is not used
as a leaf.
- Fetch the si_mtx pointer first before resorting to hashing to compute
the mutex address.
Reviewed by: McKusick
Approved by: re (kib)
- For x86, change the interrupt source method to assign an interrupt source
to a specific CPU to return an error value instead of void, thus allowing
it to fail.
- If moving an interrupt to a CPU fails due to a lack of IDT vectors in the
destination CPU, fail the request with ENOSPC rather than panicing.
- For MSI interrupts on x86 (but not MSI-X), only allow cpuset to be used
on the first interrupt in a group. Moving the first interrupt in a group
moves the entire group.
- Use the icu_lock to protect intr_next_cpu() on x86 instead of the
intr_table_lock to fix a LOR introduced in the last set of MSI changes.
- Add a new privilege PRIV_SCHED_CPUSET_INTR for using cpuset with
interrupts. Previously, binding an interrupt to a CPU only performed a
privilege check if the interrupt had an interrupt thread. Interrupts
without a thread could be bound by non-root users as a result.
- If an interrupt event's assign_cpu method fails, then restore the original
cpuset mask for the associated interrupt thread.
Approved by: re (kib)
rather than as paths, which would lead to them being treated as relative
pathnames and hence confusingly converted into absolute pathnames.
Capture flags to unmount(2) via an argument token.
Approved by: re (audit argument blanket)
MFC after: 3 days
easily determine how much space is left in the send queue; they do not
need to know the send queue size.
NetBSD revisions:
sys_socket.c r1.41, 1.42
filio.h r1.9
Obtained from: NetBSD
Approved by: re (kensmith)
loading hwpmc, but calculate at runtime and allocate the necessary space.
Also the current logic is wrong as it can lead to an endless loop.
Sponsored by: Sandvine Incorporated
Reported by: Ryan Stone <rstone at sandvine dot com>
Tested by: Giovanni Trematerra
<giovanni dot trematerra at gmail dot com>
Approved by: re (kib)
Introduce the new flag KNF_NOKQLOCK to allow event callers to be called
without KQ_LOCK mtx held.
- Modify VFS knote calls to always use KNF_NOKQLOCK flag. This is required
for ZFS as its getattr implementation may sleep.
Approved by: re (rwatson)
Reviewed by: kib
MFC after: 2 weeks
inbound data waiting on a filedescriptor, such as a pipe or a socket,
for instance by using select(2), poll(2), kqueue(2), ioctl(FIONREAD)
etc.
But we have no way of finding out if written data have yet to be
disposed of, for instance, transmitted (and ack'ed!) to some remote
host, or read by the applicantion at the far end of the pipe.
The closest we get, is calling shutdown(2) on a TCP socket in
non-blocking mode, but this has the undesirable sideeffect of
preventing future communication.
Add a complement to FIONREAD, called FIONWRITE, which returns the
number of bytes not yet properly disposed of. Implement it for
all sockets.
Background:
A HTTP server will want to time out connections, if no new request
arrives within a certain period after the last transmitted response
has actually been sent (and ack'ed).
For a busy HTTP server, this timeout can be subsecond duration.
In order to signal to a load-balancer that the connection is truly
dead, TCP_RST will be the preferred method, as this avoids the need
for a RTT delay for FIN handshaking, with a client which, surprisingly
often, no longer at the remote IP number.
If a slow, distant client is being served a response which is big
enough to fill the window, but small enough to fit in the socket
buffer, the write(2) call will return immediately.
If the session timeout is armed at that time, all bytes in the
response may not have been transmitted by the time it fires.
FIONWRITE allows the timeout to check that no data is outstanding
on the connection, before it TCP_RST's it.
Input & Idea from: rwatson
Approved by: re (kib)
in the case of a file system with a block size that is less than the page
size, cluster_rbuild() looks at too many of the page's valid bits.
Consequently, it may terminate prematurely, resulting in poor performance.
Reported by: bde
Reviewed by: tegge
Approved by: re (kib)
specific macros for each audit argument type. This makes it easier to
follow call-graphs, especially for automated analysis tools (such as
fxr).
In MFC, we should leave the existing AUDIT_ARG() macros as they may be
used by third-party kernel modules.
Suggested by: brooks
Approved by: re (kib)
Obtained from: TrustedBSD Project
MFC after: 1 week
required by video card drivers. Specifically, this change introduces
vm_cache_mode_t with an appropriate VM_CACHE_DEFAULT definition on all
architectures. In addition, this changes adds a vm_cache_mode_t parameter
to kmem_alloc_contig() and vm_phys_alloc_contig(). These will be the
interfaces for allocating mapped kernel memory and physical memory,
respectively, with non-default cache modes.
In collaboration with: jhb
Specifically, if a non-root user attempts to bind an interrupt the request
will now report failure with EPERM rather than silently failing with a
successful return code.
MFC after: 1 week
offset of the stat is not known until link time so we must emit a
function to call SYSCTL_ADD_PROC rather than using SYSCTL_PROC
directly.
- Eliminate the atomic from SCHED_STAT_INC now that it's using per-cpu
variables. Sched stats are always incremented while we're holding
a spinlock so no further protection is required.
Reviewed by: sam
additional privileges as well as not restricting the type of
sockets a user can open.
Note: the VIMAGE/vnet fetaure of of jails is still considered
experimental and cannot guarantee that privileged users
can be kept imprisoned if enabled.
Reviewed by: rwatson
Approved by: bz (mentor)
- The uid/cuid members of struct ipc_perm are now uid_t instead of unsigned
short.
- The gid/cgid members of struct ipc_perm are now gid_t instead of unsigned
short.
- The mode member of struct ipc_perm is now mode_t instead of unsigned short
(this is merely a style bug).
- The rather dubious padding fields for ABI compat with SV/I386 have been
removed from struct msqid_ds and struct semid_ds.
- The shm_segsz member of struct shmid_ds is now a size_t instead of an
int. This removes the need for the shm_bsegsz member in struct
shmid_kernel and should allow for complete support of SYSV SHM regions
>= 2GB.
- The shm_nattch member of struct shmid_ds is now an int instead of a
short.
- The shm_internal member of struct shmid_ds is now gone. The internal
VM object pointer for SHM regions has been moved into struct
shmid_kernel.
- The existing __semctl(), msgctl(), and shmctl() system call entries are
now marked COMPAT7 and new versions of those system calls which support
the new ABI are now present.
- The new system calls are assigned to the FBSD-1.1 version in libc. The
FBSD-1.0 symbols in libc now refer to the old COMPAT7 system calls.
- A simplistic framework for tagging system calls with compatibility
symbol versions has been added to libc. Version tags are added to
system calls by adding an appropriate __sym_compat() entry to
src/lib/libc/incldue/compat.h. [1]
PR: kern/16195 kern/113218 bin/129855
Reviewed by: arch@, rwatson
Discussed with: kan, kib [1]
them under COMPAT_FREEBSD[4567]. Starting with FreeBSD 5.0 the SYSV IPC
API was implemented via direct system calls (e.g. msgctl(), msgget(), etc.)
rather than indirecting through the var-args *sys() system calls. The
shmsys() system call was already effectively deprecated for all but
COMPAT_FREEBSD4 already as its implementation for the !COMPAT_FREEBSD4 case
was to simply invoke nosys().
- Modules and kernel code alike may use DPCPU_DEFINE(),
DPCPU_GET(), DPCPU_SET(), etc. akin to the statically defined
PCPU_*. Requires only one extra instruction more than PCPU_* and is
virtually the same as __thread for builtin and much faster for shared
objects. DPCPU variables can be initialized when defined.
- Modules are supported by relocating the module's per-cpu linker set
over space reserved in the kernel. Modules may fail to load if there
is insufficient space available.
- Track space available for modules with a one-off extent allocator.
Free may block for memory to allocate space for an extent.
Reviewed by: jhb, rwatson, kan, sam, grehan, marius, marcel, stas
The advantage of using a separate condvar is that we can just use
cv_signal(9) instead of cv_broadcast(9). It makes no sense to wake up
multiple threads. It also makes the TTY code easier to understand.
t_dcdwait sounds totally unrelated.
I suspect the usage of bgwait causes a lot of spurious wakeups when
threads are blocked in the background, because they will be woken up
each time a write() call is performed.
Also wakeup dcdwait when the TTY is abandoned.
rlimit RLIMIT_SWAP that limits the amount of swap that may be reserved
for the uid.
The accounting information (charge) is associated with either map entry,
or vm object backing the entry, assuming the object is the first one
in the shadow chain and entry does not require COW. Charge is moved
from entry to object on allocation of the object, e.g. during the mmap,
assuming the object is allocated, or on the first page fault on the
entry. It moves back to the entry on forks due to COW setup.
The per-entry granularity of accounting makes the charge process fair
for processes that change uid during lifetime, and decrements charge
for proper uid when region is unmapped.
The interface of vm_pager_allocate(9) is extended by adding struct ucred *,
that is used to charge appropriate uid when allocation if performed by
kernel, e.g. md(4).
Several syscalls, among them is fork(2), may now return ENOMEM when
global or per-uid limits are enforced.
In collaboration with: pho
Reviewed by: alc
Approved by: re (kensmith)
stream (TCP) sockets.
It is functionally identical to generic soreceive() but has a
number stream specific optimizations:
o does only one sockbuf unlock/lock per receive independent of
the length of data to be moved into the uio compared to
soreceive() which unlocks/locks per *mbuf*.
o uses m_mbuftouio() instead of its own copy(out) variant.
o much more compact code flow as a large number of special
cases is removed.
o much improved reability.
It offers significantly reduced CPU usage and lock contention
when receiving fast TCP streams. Additional gains are obtained
when the receiving application is using SO_RCVLOWAT to batch up
some data before a read (and wakeup) is done.
This function was written by "reverse engineering" and is not
just a stripped down variant of soreceive().
It is not yet enabled by default on TCP sockets. Instead it is
commented out in the protocol initialization in tcp_usrreq.c
until more widespread testing has been done.
Testers, especially with 10GigE gear, are welcome.
MFP4: r164817 //depot/user/andre/soreceive_stream/
long mbuf chain into an arbitrary large uio in a single step.
It is a functional mirror image of m_uiotombuf().
This function is supposed to be used instead of hand rolled code
with the same purpose and to concentrate it into one place for
potential further optimization or hardware assistance.
chains) to pure data mbufs using m_demote(). This removes the
packet header and all m_tag information as they are not meaningful
anymore on a stream socket where mbufs are linked through m->m_next.
Strictly speaking a packet header can be only ever valid on the first
mbuf in an m_next chain.
sbcompress() was doing this already when the mbuf chain layout lent
itself to it (e.g. header splitting or merge-append), just not
consistently.
This frees resources at socket buffer append time instead of at
sbdrop_internal() time after data has been read from the socket.
For MAC the per packet information has done its duty and during
socket buffer appending the policy of the socket itself takes over.
With the append the packet boundaries disappear naturally and with
it any context that was based on it. None of the residual information
from mbuf headers in the socket buffer on stream sockets was looked at.
- remove HT_HEADER test (MT_HEADER == MT_DATA for some time now)
- be more pedantic about m_nextpkt in other than first mbuf
- update m_flags to be retained
vn_open_cred in default implementation. Valid struct ucred is needed for
audit and MAC, and curthread credentials may be wrong.
This further requires modifying the interface of vn_fullpath(9), but it
is out of scope of this change.
Reviewed by: rwatson
vn_open_cred invocations shall not audit namei path.
In particular, specify VN_OPEN_NOAUDIT for dotdot lookup performed by
default implementation of vop_vptocnp, and for the open done for core
file. vn_fullpath is called from the audit code, and vn_open there need
to disable audit to avoid infinite recursion. Core file is created on
return to user mode, that, in particular, happens during syscall return.
The creation of the core file is audited by direct calls, and we do not
want to overwrite audit information for syscall.
Reported, reviewed and tested by: rwatson
Now that we start to use credentials on character devices more often
(because of MPSAFE TTY), move the prison-checks that are in place in the
TTY code into devfs.
Instead of strictly comparing the prisons, use the more common
prison_check() function to compare credentials. This means that
pseudo-terminals are only visible in devfs by processes within the same
jail and parent jails.
Even though regular users in parent jails can now interact with
pseudo-terminals from child jails, this seems to be the right approach.
These processes are also capable of interacting with the jailed
processes anyway, through signals for example.
Reviewed by: kib, rwatson (older version)
NGROUPS_MAX, eliminate ABI dependencies on them, and raise the to 1024
and 1023 respectively. (Previously they were equal, but under a close
reading of POSIX, NGROUPS_MAX was defined to be too large by 1 since it
is the number of supplemental groups, not total number of groups.)
The bulk of the change consists of converting the struct ucred member
cr_groups from a static array to a pointer. Do the equivalent in
kinfo_proc.
Introduce new interfaces crcopysafe() and crsetgroups() for duplicating
a process credential before modifying it and for setting group lists
respectively. Both interfaces take care for the details of allocating
groups array. crsetgroups() takes care of truncating the group list
to the current maximum (NGROUPS) if necessary. In the future,
crsetgroups() may be responsible for insuring invariants such as sorting
the supplemental groups to allow groupmember() to be implemented as a
binary search.
Because we can not change struct xucred without breaking application
ABIs, we leave it alone and introduce a new XU_NGROUPS value which is
always 16 and is to be used or NGRPS as appropriate for things such as
NFS which need to use no more than 16 groups. When feasible, truncate
the group list rather than generating an error.
Minor changes:
- Reduce the number of hand rolled versions of groupmember().
- Do not assign to both cr_gid and cr_groups[0].
- Modify ipfw to cache ucreds instead of part of their contents since
they are immutable once referenced by more than one entity.
Submitted by: Isilon Systems (initial implementation)
X-MFC after: never
PR: bin/113398 kern/133867
Instead of locking the local unp followed by the remote unp, use the same
locking model as accept() and read lock the global link lock followed by
the remote unp while fetching the remote sockaddr.
Reported by: Mel Flynn mel.flynn of mailing.thruhere.net
Reviewed by: rwatson
MFC after: 1 week
allocator for the jumbo frames zones. This change has two benefits: (1) a
custom back-end deallocator is no longer required. UMA's standard
deallocator suffices. (2) It eliminates a potentially confusing artifact
of using contigmalloc(): The malloc(9) statistics contain bogus information
about the usage of jumbo frames. Specifically, the malloc(9) statistics
report all jumbo frames in use whereas the UMA zone statistics report the
"truth" about the number in use vs. the number free.
in the type field of system call tables. Specifically, one can now use
the 'NO*' types as flags in addition to the 'COMPAT*' types. For example,
to tag 'COMPAT*' system calls as living in a KLD via NOSTD. The COMPAT*
type is required to be listed first in this case.
- Add new functions 'type()' and 'flag()' to the embedded awk script in
makesyscalls.sh that return true if a requested flag is found in the
type field ($3). The flag() function checks all of the flags in the
field, but type() only checks the first flag. type() is meant to be
used in the top-level "switch" statement and flag() should be used
otherwise.
- Retire the CPT_NOA type, it is now replaced with "COMPAT|NOARGS" using
the flags approach.
- Tweak the comment descriptions of COMPAT[46] system calls so that they
say "freebsd[46] foo" rather than "old foo".
- Document the COMPAT6 type.
- Sync comments in compat32 syscall table with the master table.
- Mark nfsclnt as UNIMPL. It should have been NOSTD instead of NOIMPL back
when it lived in nfsclient.ko, but it was removed from that a long time
ago.
Actually, as it did receive few tuning, the support is disabled by
default, but it can opt-in with the option ADAPTIVE_LOCKMGRS.
Due to the nature of lockmgrs, adaptive spinning needs to be
selectively enabled for any interested lockmgr.
The support is bi-directional, or, in other ways, it will work in both
cases if the lock is held in read or write way. In particular, the
read path is passible of further tunning using the sysctls
debug.lockmgr.retries and debug.lockmgr.loops . Ideally, such sysctls
should be axed or compiled out before release.
Addictionally note that adaptive spinning doesn't cope well with
LK_SLEEPFAIL. The reason is that many (and probabilly all) consumers
of LK_SLEEPFAIL are mainly interested in knowing if the interlock was
dropped or not in order to reacquire it and re-test initial conditions.
This directly interacts with adaptive spinning because lockmgr needs
to drop the interlock while spinning in order to avoid a deadlock
(further details in the comments inside the patch).
Final note: finding someone willing to help on tuning this with
relevant workloads would be either very important and appreciated.
Tested by: jeff, pho
Requested by: many
The code that was in place in exit1() was mainly based on code from the
old TTY layer. The main reason behind this, was because at one moment I
ran a system that had two TTY layers in place at the same time. It is
now sufficient to do the following:
- Remove references from the session structure to the TTY vnode and the
session leader.
- If we have a controlling TTY and the session used by the TTY is equal
to our session, send the SIGHUP.
- If we have a vnode to the controlling TTY which has not been revoked,
revoke it.
While there, change sys/kern/tty.c to use s_ttyp in the comparison
instead of s_ttyvp. It should not make any difference, because s_ttyvp
can only become null when the session leader already left, but it's
nicer to compare against the proper value.
any open file descriptors >= 'lowfd'. It is largely identical to the same
function on other operating systems such as Solaris, DFly, NetBSD, and
OpenBSD. One difference from other *BSD is that this closefrom() does not
fail with any errors. In practice, while the manpages for NetBSD and
OpenBSD claim that they return EINTR, they ignore internal errors from
close() and never return EINTR. DFly does return EINTR, but for the common
use case (closing fd's prior to execve()), the caller really wants all
fd's closed and returning EINTR just forces callers to call closefrom() in
a loop until it stops failing.
Note that this implementation of closefrom(2) does not make any effort to
resolve userland races with open(2) in other threads. As such, it is not
multithread safe.
Submitted by: rwatson (initial version)
Reviewed by: rwatson
MFC after: 2 weeks
Right now the only way to make tcsetsid(3)/TIOCSCTTY work, is by
ensuring the session leader is dead. This means that an application that
catches SIGHUPs and performs a sleep prevents us from assigning a new
session leader.
Change the code to make it work on revoked TTYs as well. This allows us
to change init(8) to make the shutdown script run in a more clean
environment.
