Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add CPU percentage limit enforcement to RCTL. The resouce name is "pcpu".
It was implemented by Rudolf Tomori during Google Summer of Code 2012.

Stop treating system processes as special. This fixes panics
like the one triggered by this:

# kldload geom_vinum
# pwait `pgrep -S gv_worker` &
# kldunload geom_vinum

or this:

GEOM_JOURNAL: Shutting down geom gjournal 3464572051.
panic: destroying non-empty racct: 1 allocated for resource 6

which were tracked by jh@ to be caused by checking p->p_flag,
while it wasn't initialised yet. Basically, during fork, the code
checked p_flag, concluded the process isn't marked as P_SYSTEM,
incremented the counter, and later on, when exiting, checked that
the process was marked as P_SYSTEM, and thus didn't decrement it.

Also, I believe there wasn't any good reason for checking P_SYSTEM
in the first place.

Tested by: jh

Enforce upper bound on the input buffer length.

Reported by: Mateusz Guzik

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

This means that their use is restricted to a single C file.

Fix another bug introduced in r225641, which caused rctl to access certain
fields in 'struct proc' before they got initialized in do_fork().

MFC after: 3 days

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)

Fix whitespace.

Submitted by: amdmi3
Approved by: re (rwatson)

Work around a kernel panic triggered by forkbomb with an rctl rule
such as j:name:maxproc:sigkill=100. Proper fix - deferring psignal
to a taskqueue - is somewhat complicated and thus will happen
after 9.0.

Approved by: re (kib)

Since r224036 the cputime and wallclock are supposed to be in seconds,
not microseconds. Make it so.

Approved by: re (kib)

Rename resource names to match these in login.conf.

Style fix - macros are supposed to be uppercase.

Remove definitions for RACCT_FSIZE and RACCT_SBSIZE - these two are rather
performance-sensitive and not that useful, so I won't be merging them
before 9.0.

Change the way rctl interfaces with jails by introducing prison_racct
structure, which acts as a proxy between them. This makes jail rules
persistent, i.e. they can be added before jail gets created, and they
don't disappear when the jail gets destroyed.

Rename a misnamed structure field (hr_loginclass), and reorder priv(9)
constants to match the order and naming of syscalls. No functional changes.

Add rctl. It's used by racct to take user-configurable actions based
on the set of rules it maintains and the current resource usage. It also
privides userland API to manage that ruleset.

Sponsored by: The FreeBSD Foundation
Reviewed by: kib (earlier version)