and make the sleep length depend on value of variable forkfsleep;
it's set to zero by default (no sleep)
this is a preparation for making the sleep length settable via sysctl
- leave 5 processes for root-only use, the previous value of 1
was unsufficient to execute additional commands once logged, and
perhaps also not enough to actually login remotely with recent (open)sshd
- protect the log of "proc: table full" with ratecheck(), so that
the message is only logged once per 10 seconds; though syslogd normally
doesn't pass the repeated messages through, this avoids flooding
syslogd and potentially also screen/logs
- If the process hits either system limit of number of processes in system,
or user's limit of same, force the process to sleep for 0.5 seconds
before returning failure. This turns 2000 rampaging fork monsters into
2000 harmlessly snoozing fork monsters.
The sleep is intentionally uninterruptible by signals.
These are not intended as ultimate protection agains fork-bombs.
Determined attacker can eat CPU differently than via repeating
fork() calls. But this is good enough to help protect against
programming mistakes or simple-minded tests.
Based on FreeBSD kern_fork.c change in revision 1.132 by
Mike Silbersack <silby at FreeBSD org>
Change also discussed on tech-kern@NetBSD.org, thread
'Fork bomb protection patch'.
backed by physical pages (ie. because it reused a previously-freed one),
so that we can skip a bunch of useless work in that case.
this fixes the underlying problem behind PR 18543, and also speeds up fork()
quite a bit (eg. 7% on my pc, 1% on my ultra2) when we get a cache hit.
that can be used to block a process after fork(2) or exec(2) calls. The
new process is created in the SSTOP state and is never scheduled for running.
This feature is designed so that it is esay to attach the process using gdb
before it has done anything.
It works also with sproc, kthread_create, clone...
kqueue provides a stateful and efficient event notification framework
currently supported events include socket, file, directory, fifo,
pipe, tty and device changes, and monitoring of processes and signals
kqueue is supported by all writable filesystems in NetBSD tree
(with exception of Coda) and all device drivers supporting poll(2)
based on work done by Jonathan Lemon for FreeBSD
initial NetBSD port done by Luke Mewburn and Jason Thorpe
only signal handler array sharable between threads
move other random signal stuff from struct proc to struct sigctx
This addresses kern/10981 by Matthew Orgass.
* __HAVE_SYSCALL_INTERN. If this is defined, e_syscall is replaced by
e_syscall_intern, which is called at key places in the kernel. This can be
used to set a MD syscall handler pointer. This obsoletes and replaces the
*_HAS_SEPARATED_SYSCALL flags.
* __HAVE_MINIMAL_EMUL. If this is defined, certain (deprecated) elements in
struct emul are omitted.
and adding it to allproc) after it's fully initialized.
this prevents the scheduler from coming in via a clock interrupt
and tripping over a partially-initialized proc.
emulation-specific data
add process exit, exec and fork function hooks into struct emul:
* e_proc_fork() - called in fork1() after the new forked process is setup
* e_proc_exec() - called in sys_execve() after the executed process is setup
* e_proc_exit() - called in exit1() after all the other process cleanups are
done, right before machine-dependant switch to new context; also called
for "old" emulation from sys_execve() if emulation of executed program and
the original process is different
This was discussed on tech-kern.
use that to inform about way to raise current limit when we reach maximum
number of processes, descriptors or vnodes
XXX hopefully I catched all users of tablefull()
<vm/pglist.h> -> <uvm/uvm_pglist.h>
<vm/vm_inherit.h> -> <uvm/uvm_inherit.h>
<vm/vm_kern.h> -> into <uvm/uvm_extern.h>
<vm/vm_object.h> -> nothing
<vm/vm_pager.h> -> into <uvm/uvm_pager.h>
also includes a bunch of <vm/vm_page.h> include removals (due to redudancy
with <vm/vm.h>), and a scattering of other similar headers.
p_cpu member to struct proc. Use this in certain places when
accessing scheduler state, etc. For the single-processor case,
just initialize p_cpu in fork1() to avoid having to set it in the
low-level context switch code on platforms which will never have
multiprocessing.
While I'm here, comment a few places where there are known issues
for the SMP implementation.
doing a cpu_set_kpc(), just pass the entry point and argument all
the way down the fork path starting with fork1(). In order to
avoid special-casing the normal fork in every cpu_fork(), MI code
passes down child_return() and the child process pointer explicitly.
This fixes a race condition on multiprocessor systems; a CPU could
grab the newly created processes (which has been placed on a run queue)
before cpu_set_kpc() would be performed.
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.
The old timeout()/untimeout() API has been removed from the kernel.
write lock when doing PID allocation, and during the process exit path.
Use a read lock every where else, including within schedcpu() (interrupt
context). Note that holding the write lock implies blocking schedcpu()
from running (blocks softclock).
PID allocation is now MP-safe.
Note this actually fixes a bug on single processor systems that was probably
extremely difficult to tickle; it was possible that schedcpu() would run
off a bad pointer if the right clock interrupt happened to come in the
middle of a LIST_INSERT_HEAD() or LIST_REMOVE() to/from allproc.
the child inherits the stack pointer from the parent (traditional
behavior). Like the signal stack, the stack area is secified as
a low address and a size; machine-dependent code accounts for stack
direction.
This is required for clone(2).
parent, specified at fork time. Specify a new flag to wait4(2), WALTSIG,
to wait for processes which use an alternate exit signal.
This is required for clone(2).
