mac_thread_userret() only if PS_MACPEND is set in the process AST mask.
This avoids the cost of the entry point in the common case, but
requires policies interested in the userret event to set the flag
(protected by the scheduler lock) if they do want the event. Since
all the policies that we're working with which use mac_thread_userret()
use the entry point only selectively to perform operations deferred
for locking reasons, this maintains the desired semantics.
Approved by: re
Requested by: bde
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
- Begin moving scheduler specific functionality into sched_4bsd.c
- Replace direct manipulation of scheduler data with hooks provided by the
new api.
- Remove KSE specific state modifications and single runq assumptions from
kern_switch.c
Reviewed by: -arch
sched_lock. This means that we no longer access p_limit in mi_switch()
and the p_limit pointer can be protected by the proc lock.
- Remove PRS_ZOMBIE check from CPU limit test in mi_switch(). PRS_ZOMBIE
processes don't call mi_switch(), and even if they did there is no longer
the danger of p_limit being NULL (which is what the original zombie check
was added for).
- When we bump the current processes soft CPU limit in ast(), just bump the
private p_cpulimit instead of the shared rlimit. This fixes an XXX for
some value of fix. There is still a (probably benign) bug in that this
code doesn't check that the new soft limit exceeds the hard limit.
Inspired by: bde (2)
modules to perform MAC-related events when a thread returns to user
space. This is required for policies that have floating process labels,
as it's not always possible to acquire the process lock at arbitrary
points in the stack during system call processing; process labels might
represent traditional authentication data, process history information,
or other data.
LOMAC will use this entry point to perform the process label update
prior to the thread returning to userspace, when plugged into the MAC
framework.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
has exceeded its CPU time limit.
- In mi_switch(), set PS_XCPU when the CPU time limit is exceeded.
- Perform actual CPU time limit exceeded work in ast() when PS_XCPU is set.
Requested by: many
gets signals operating based on a TailQ, and is good enough to run X11,
GNOME, and do job control. There are some intricate parts which could be
more refined to match the sigset_t versions, but those require further
evaluation of directions in which our signal system can expand and contract
to fit our needs.
After this has been in the tree for a while, I will make in kernel API
changes, most notably to trapsignal(9) and sendsig(9), to use ksiginfo
more robustly, such that we can actually pass information with our
(queued) signals to the userland. That will also result in using a
struct ksiginfo pointer, rather than a signal number, in a lot of
kern_sig.c, to refer to an individual pending signal queue member, but
right now there is no defined behaviour for such.
CODAFS is unfinished in this regard because the logic is unclear in
some places.
Sponsored by: New Gold Technology
Reviewed by: bde, tjr, jake [an older version, logic similar]
failed to set signal flags proprly for ast()
failed to set signal flags proprly for ast()
failed to set signal flags proprly for ast()
failed to set signal flags proprly for ast()
The ability to schedule multiple threads per process
(one one cpu) by making ALL system calls optionally asynchronous.
to come: ia64 and power-pc patches, patches for gdb, test program (in tools)
Reviewed by: Almost everyone who counts
(at various times, peter, jhb, matt, alfred, mini, bernd,
and a cast of thousands)
NOTE: this is still Beta code, and contains lots of debugging stuff.
expect slight instability in signals..
they aren't in the usual path of execution for syscalls and traps.
The main complication for this is that we have to set flags to control
ast() everywhere that changes the signal mask.
Avoid locking in userret() in most of the remaining cases.
Submitted by: luoqi (first part only, long ago, reorganized by me)
Reminded by: dillon
back into the calling MD code. The MD code must ensure no races between
checking the astpening flag and returning to usermode.
Submitted by: peter (ia64 bits)
Tested on: alpha (peter, jeff), i386, ia64 (peter), sparc64
Instead of caching the ucred reference, just go ahead and eat the
decerement and increment of the refcount. Now that Giant is pushed down
into crfree(), we no longer have to get Giant in the common case. In the
case when we are actually free'ing the ucred, we would normally free it on
the next kernel entry, so the cost there is not new, just in a different
place. This also removse td_cache_ucred from struct thread. This is
still only done #ifdef DIAGNOSTIC.
[ missed this file in the previous commit ]
Tested on: i386, alpha
While in userland, keep the thread's ucred reference in a shadow
field so that the usual place to store it is NULL.
If DIAGNOSTIC is not set, the thread ucred is kept valid until the next
kernel entry, at which time it is checked against the process cred
and possibly corrected. Produces a BIG speedup in
kernels with INVARIANTS set. (A previous commit corrected it
for the non INVARIANTS case already)
Reviewed by: dillon@freebsd.org
reaquiring it. In the same vein, don't bother dropping the thread cred
when goinf ot userland. We are guaranteed to nned it when we come back,
(which we are guaranteed to do).
Reviewed by: jhb@freebsd.org, bde@freebsd.org (slightly different version)
mutex releases to not require flags for the cases when preemption is
not allowed:
The purpose of the MTX_NOSWITCH and SWI_NOSWITCH flags is to prevent
switching to a higher priority thread on mutex releease and swi schedule,
respectively when that switch is not safe. Now that the critical section
API maintains a per-thread nesting count, the kernel can easily check
whether or not it should switch without relying on flags from the
programmer. This fixes a few bugs in that all current callers of
swi_sched() used SWI_NOSWITCH, when in fact, only the ones called from
fast interrupt handlers and the swi_sched of softclock needed this flag.
Note that to ensure that swi_sched()'s in clock and fast interrupt
handlers do not switch, these handlers have to be explicitly wrapped
in critical_enter/exit pairs. Presently, just wrapping the handlers is
sufficient, but in the future with the fully preemptive kernel, the
interrupt must be EOI'd before critical_exit() is called. (critical_exit()
can switch due to a deferred preemption in a fully preemptive kernel.)
I've tested the changes to the interrupt code on i386 and alpha. I have
not tested ia64, but the interrupt code is almost identical to the alpha
code, so I expect it will work fine. PowerPC and ARM do not yet have
interrupt code in the tree so they shouldn't be broken. Sparc64 is
broken, but that's been ok'd by jake and tmm who will be fixing the
interrupt code for sparc64 shortly.
Reviewed by: peter
Tested on: i386, alpha
remove the check from addupc_task(). It would need sched_lock while
testing the flag anyways.
- Always read sticks while holding sched_lock using a temporary variable
where needed.
- Always init prticks to 0 in ast() to quiet a warning.
- The MD functions critical_enter/exit are renamed to start with a cpu_
prefix.
- MI wrapper functions critical_enter/exit maintain a per-thread nesting
count and a per-thread critical section saved state set when entering
a critical section while at nesting level 0 and restored when exiting
to nesting level 0. This moves the saved state out of spin mutexes so
that interlocking spin mutexes works properly.
- Most low-level MD code that used critical_enter/exit now use
cpu_critical_enter/exit. MI code such as device drivers and spin
mutexes use the MI wrappers. Note that since the MI wrappers store
the state in the current thread, they do not have any return values or
arguments.
- mtx_intr_enable() is replaced with a constant CRITICAL_FORK which is
assigned to curthread->td_savecrit during fork_exit().
Tested on: i386, alpha
userland. The per thread ucred reference is immutable and thus needs no
locks to be read. However, until all the proc locking associated with
writes to p_ucred are completed, it is still not safe to use the per-thread
reference.
Tested on: x86 (SMP), alpha, sparc64
as a physical atomic operation. That would require the code to use the
atomic API, which it does not. Instead, the operation is made psuedo
atomic (hence the quotes) by use of the lock to protect clearing all of the
flags in question.
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.
Sorry john! (your next MFC will be a doosie!)
Reviewed by: peter@freebsd.org, dillon@freebsd.org
X-MFC after: ha ha ha ha
Instead introduce the [M] prefix to existing keywords. e.g.
MSTD is the MP SAFE version of STD. This is prepatory for a
massive Giant lock pushdown. The old MPSAFE keyword made
syscalls.master too messy.
Begin comments MP-Safe procedures with the comment:
/*
* MPSAFE
*/
This comments means that the procedure may be called without
Giant held (The procedure itself may still need to obtain
Giant temporarily to do its thing).
sv_prepsyscall() is now MP SAFE and assumed to be MP SAFE
sv_transtrap() is now MP SAFE and assumed to be MP SAFE
ktrsyscall() and ktrsysret() are now MP SAFE (Giant Pushdown)
trapsignal() is now MP SAFE (Giant Pushdown)
Places which used to do the if (mtx_owned(&Giant)) mtx_unlock(&Giant)
test in syscall[2]() in */*/trap.c now do not. Instead they
explicitly unlock Giant if they previously obtained it, and then
assert that it is no longer held to catch broken system calls.
Rebuild syscall tables.
the process of exiting the kernel. The ast() function now loops as long
as the PS_ASTPENDING or PS_NEEDRESCHED flags are set. It returns with
preemption disabled so that any further AST's that arrive via an
interrupt will be delayed until the low-level MD code returns to user
mode.
- Use u_int's to store the tick counts for profiling purposes so that we
do not need sched_lock just to read p_sticks. This also closes a
problem where the call to addupc_task() could screw up the arithmetic
due to non-atomic reads of p_sticks.
- Axe need_proftick(), aston(), astoff(), astpending(), need_resched(),
clear_resched(), and resched_wanted() in favor of direct bit operations
on p_sflag.
- Fix up locking with sched_lock some. In addupc_intr(), use sched_lock
to ensure pr_addr and pr_ticks are updated atomically with setting
PS_OWEUPC. In ast() we clear pr_ticks atomically with clearing
PS_OWEUPC. We also do not grab the lock just to test a flag.
- Simplify the handling of Giant in ast() slightly.
Reviewed by: bde (mostly)
lock until after grabbing the sched_lock to avoid CURSIG racing with
psignal.
- Don't grab Giant for addupc_task() as it isn't needed.
Reported by: tegge (signal race), bde (addupc_task a while back)
simpler for npx exceptions that start as traps (no assembly required...)
and works better for npx exceptions that start as interrupts (there is
no longer a problem for nested interrupts).
Submitted by: original (pre-SMPng) version by luoqi
