- Reorder fork1() to do malloc() and other blocking operations prior to
acquiring the needed process locks.
- The new process inherit's the credentials of curthread, not the
credentials of the old process.
- Document a really weird race that will come up with KSE allows multiple
kernel threads per process.
exit1() we don't have to release it until we acquire schd_lock to
call cpu_throw().
- Since we can switch at any time due to preemption or a lock release
prior to acquiring sched_lock, don't update switchtime and switchticks
until the very end of exit1() after we have acquired sched_lock.
- Interlock the proctree_lock and proc lock in wait1() and exit1() to
avoid lost wakeups when a parent blocks waiting for a child to exit at
the bottom of wait1(). In exit1() the proc lock interlocked with
proctree_lock (and released after acquiring sched_lock) is that of
the parent process.
- In wait1() use an exclusive lock of proctree lock while we are
looking for a process to harvest. This allows us to completely
remove all references to the process once we've found one (i.e.,
disconnect it from pgrp's, session's, zombproc list, and it's parent's
children list) "atomically" without needing to worry about a lock
upgrade.
- We don't need sched_lock to test if p_stat is SZOMB or SSTOP when holding
the proc lock since the proc lock is always held with p_stat is set to
SZOMB or SSTOP.
- Protect nprocs with an xlock of the allproc_lock.
locks the process.
- Defer other blocking operations such as vrele()'s until after we
release locks.
- execsigs() now requires the proc lock to be held when it is called
rather than locking the process internally.
mallochash. Mallochash is going to go away as soon as I introduce the
kfree/kmalloc api and partially overhaul the malloc wrapper. This can't happen
until all users of the malloc api that expect memory to be aligned on the size
of the allocation are fixed.
Implement the following checks on freed memory in the bucket path:
- Slab membership
- Alignment
- Duplicate free
This previously was only done if we skipped the buckets. This code will slow
down INVARIANTS a bit, but it is smp safe. The checks were moved out of the
normal path and into hooks supplied in uma_dbg.
Turn the sigio sx into a mutex.
Sigio lock is really only needed to protect interrupts from dereferencing
the sigio pointer in an object when the sigio itself is being destroyed.
In order to do this in the most unintrusive manner change pgsigio's
sigio * argument into a **, that way we can lock internally to the
function.
loading breakage'). The patch fixes serious issues with the VFS
operations vector array which results in a crash when a filesystem module
adding a new VOP is loaded into the kernel. Basically what was happening
before was that the old operations vector was being freed and a new one
allocated. The original MALLOC code tended to reuse the same address
for the case and so the bug did not rear its ugly head until the new memory
subsystem was emplaced.
This patch replaces the temporary workaround Dave O'Brien comitted in 1.58.
The patch is clean enough that I intend to MFC it to stable at some point.
Submitted by: Alexander Kabaev <ak03@gte.com>
MFC after: 1 week
0xdeadc0de and then check for it just before memory is handed off as part
of a new request. This will catch any post free/pre alloc modification of
memory, as well as introduce errors for anything that tries to dereference
it as a pointer.
This code takes the form of special init, fini, ctor and dtor routines that
are specificly used by malloc. It is in a seperate file because additional
debugging aids will want to live here as well.
Requested by: bde
Since locking sigio_lock is usually followed by calling pgsigio(),
move the declaration of sigio_lock and the definitions of SIGIO_*() to
sys/signalvar.h.
While I am here, sort include files alphabetically, where possible.
malloc profiling) also modified the set of pre-defined buckets for the
memory allocator. For reasons unknown to me, this resulted in extensive
memory corruption in the kernel, in particular on SMP boxes, so I'm
committing this work-around until Jeff gets a chance to debug it
properly. David Wolfskill pointed me at this commit as the one that
might be a problem; I've been running this code on two dual-processor
burn-in boxes for about 12 hours now, and the rate of panics due to
memory corruption has dropped to zero (from one every five minutes).
Hopefully not treading on the toes of: jeff
SIGCHLD handler is SIG_IGN. This is a reimplementation of the
problematic revision 1.131 of kern_exit.c. To avoid accessing process
UPAGES, we set a new procsig flag when the SIGCHLD handler is SIG_IGN
and use that instead.
Otherwise we fall back to using the static hints the next time around.
We still have the leftover fallback code there which meant that we skipped
the use_hints checking on the second and subsequent calls. Also, be a bit
more careful about walking off the end of the envp array.
I've extracted this from a larger diff. I hope I didn't miss anything...
of a socket. This avoids lock order reversal caused by locking a
process in pgsigio().
sowakeup() and the callers of it (sowwakeup, soisconnected, etc.) now
require sigio_lock to be locked. Provide sowwakeup_locked(),
soisconnected_locked(), and so on in case where we have to modify a
socket and wake up a process atomically.
by other bits of code, split struct timecounter into two.
struct timecounter contains just the bits which pertains to the hardware
counter and the reading of it.
struct timehands (as in "the hands on a clock") contains all the ugly bit
fidling stuff. Statically compile ten timehands.
This commit is the functional part. A later cosmetic patch will rename
various variables and fieldnames.
timeout loop.
Limit the rate at which we wind the timecounters to approx 1000 Hz.
This limits the precision of the get{bin,nano,micro}[up]time(9)
functions to roughly a millisecond.
timecounter will be used starting at the next second, which is
good enough for sysctl purposes. If better adjustment is needed
the NTP PLL should be used.
LRU fashion when the listen queue fills up. Previously, there was
no mechanism to kick out old sockets, leading to an easy DoS of
daemons using accept filtering.
Reviewed by: alfred
MFC after: 3 days
