in a user process gaining visibility into the 'old' contents of a filesystem
block. There were two cases: (1) when uiomove() fails (user process issues
illegal write), and (2) when uiomove() overlaps a mmap() of the same file at
the same offset (fault -> recursive buffer I/O reads contents of old block).
Unfortunately 1.72 also had the unintended effect of forcing the filesystem
to do a read-before-write in the case of a full-block-write (non append case),
e.g. 'dd if=/dev/zero of=test.dat bs=1m count=256 conv=notrunc'. This
destroys performance.. not only is a read forced for every write, but
clustering breaks as well.
The solution is to clear the buffer manually in the full-block case rather
then asking BALLOC to do it (BALLOC issues the read-before-write). In the
partial-block case we want BALLOC to do it because the read-before-write
is necessary. This patch should greatly improve database and news-feed
server performance.
Found by: MKI <mki@mozone.net>
MFC after: 3 days
executes in the usage() message and manual page. Use "utility" instead of
"command" in both places to emphasise that shell builtins etc. will not work,
and to be consistent with the terminology used by POSIX.
PR: 39210
Submitted by: Danny J. Zerkel <dzerkel@columbus.rr.com>
MFC after: 1 week
uifind() with a proc lock held.
change_ruid() and change_euid() have been modified to take a uidinfo
structure which will be pre-allocated by callers, they will then
call uihold() on the uidinfo structure so that the caller's logic
is simplified.
This allows one to call uifind() before locking the proc struct and
thereby avoid a potential blocking allocation with the proc lock
held.
This may need revisiting, perhaps keeping a spare uidinfo allocated
per process to handle this situation or re-examining if the proc
lock needs to be held over the entire operation of changing real
or effective user id.
Submitted by: Don Lewis <dl-freebsd@catspoiler.org>
release of Giant.
o Reduce the scope of GIANT_REQUIRED in vm_map_insert().
These changes will enable us to remove the acquisition and release
of Giant from obreak().
so that /dev/mumble can be the entrypoint to some networking graph,
e.g. a tunnel or a remote tape drive or whatever...
Not fully tested (by me) yet.
Submitted by: Mark Santcroos <marks@ripe.net>
MFC after: 3 weeks
This facilitates the use in circumstances where you are using a serial
console as well. GDB doesn't support anything higher than 9600 baud (19k2
if you are lucky), but the console does.
allocated slabs and bucket caches for free items. It will not go ask the vm
for pages. This differs from M_NOWAIT in that it not only doesn't block, it
doesn't even ask.
- Add a new zcreate option ZONE_VM, that sets the BUCKETCACHE zflag. This
tells uma that it should only allocate buckets out of the bucket cache, and
not from the VM. It does this by using the M_NOVM option to zalloc when
getting a new bucket. This is so that the VM doesn't recursively enter
itself while trying to allocate buckets for vm_map_entry zones. If there
are already allocated buckets when we get here we'll still use them but
otherwise we'll skip it.
- Use the ZONE_VM flag on vm map entries and pv entries on x86.
during the previous probe are stale.
What really should be done is route the probe through
device_probe_and_attach bit this is one of those ICBBATIASS (I can't be
bothered as there is a simpler solution). The user can easily replug the
device after kldloading a new device driver.
'make load' if an object dir was, like it is used in /sys/modules. I.e.
cd /sys/modules/umass
make obj
make
make load
works again without having to install the module.
If no objdir was used the module in the current directory is used.
magic numbers. Use stxa_sync instead of stxa; membar #Sync; to ensure
that no instruction is placed between the two. This can cause random
corruption even though interrupts are already disabled.
Fixed pow(x, y) when x is very close to -1.0 and y is a very large odd
integer. E.g., pow(-1.0 - pow(2.0, -52.0), 1.0 + pow(2.0, 52.0)) was
0.0 instead of being very close to -exp(1.0).
PR: 39236
Submitted by: Stephen L Moshier <steve@moshier.net>
e_powf.c:
Apply the same patch although it is just cosmetic because odd integers
large enough to cause the problem are too large to be precisely represented
as floats.
MFC after: 1 week
"snapend - l" underflows; this fixes a buffer overflow with malformed
NFS packets, and may fix other buffer overflows with malformed packets.
Obtained from: tcpdump.org CVS
