- witness_lock() is split into two pieces: witness_checkorder() and
witness_lock(). Witness_checkorder() determines if acquiring a specified
lock at the time it is called would result in a lock order. It
optionally adds a new lock order relationship as well. witness_lock()
updates witness's data structures to assume that a lock has been acquired
by stick a new lock instance in the appropriate lock instance list.
- The mutex and sx lock functions now call checkorder() prior to trying to
acquire a lock and continue to call witness_lock() after the acquire is
completed. This will let witness catch a deadlock before it happens
rather than trying to do so after the threads have deadlocked (i.e. never
actually report it).
- A new function witness_defineorder() has been added that adds a lock
order between two locks at runtime without having to acquire the locks.
If the lock order cannot be added it will return an error. This function
is available to programmers via the WITNESS_DEFINEORDER() macro which
accepts either two mutexes or two sx locks as its arguments.
- A few simple wrapper macros were added to allow developers to call
witness_checkorder() anywhere as a way of enforcing locking assertions
in code that might acquire a certain lock in some situations. The
macros are: witness_check_{mutex,shared_sx,exclusive_sx} and take an
appropriate lock as the sole argument.
- The code to remove a lock instance from a lock list in witness_unlock()
was unnested by using a goto to vastly improve the readability of this
function.
instead of taskqueue_swi. This shaves from 1 to 10% of the overhead.
Overhaul the locking once more, there was a few possible races that
are now closed.
Joe Marcus Clarke <marcus@FreeBSD.ORG>, subshells could lose a
non-zero exit status.
This commit is Joe's proposed patch. Thanks!
I verified that the problem Joe found is fixed and I ran a full world
with this patch.
I don't plan to ever commit language patches to /bin/sh again. It is
a minefield too big to navigate without a full-time committment, which
I am not willing to do on our /bin/sh.
Under normal circumstances I would recommend using NetBSD's sh which
has a lot of language fixes (like the ones what these patches were
about) but unfortunately they had implemented broken signal behaviour
for shellscript containing interactive programs. Similar issues apply
to pdksh which is OpenBSD's sh.
From my perspective bash2 is the only really working bourne sh out
there and that one is GPLed. Oh well.
installkernel.debug target (in the kernel build directory) which is
only defined if the kernel was configured for debugging which it is
not the case for GENERIC kernels on release branches.
panic() so that the buffer overflow just beyond this point is always
caught, even when the code is not compiled with INVARIANTS.
Change chn_setblocksize() buffer reallocation code to attempt to avoid
the feed_vchan16() buffer overflow by attempting to always keep the
bufsoft buffer at least as large as the bufhard buffer.
Print a diagnositic message
Danger! %s bufsoft size increasing from %d to %d after CHANNEL_SETBLOCKSIZE()
if our best attempts fail. If feed_vchan16() were to be called by
the interrupt handler while locks are dropped in chn_setblocksize()
to increase the size bufsoft to match the size of bufhard, the panic()
code in feed_vchan16() will be triggered. If the diagnostic message
is printed, it is a warning that a panic is possible if the system
were to see events in an "unlucky" order.
Change the locking code to avoid the need for MTX_RECURSIVE mutexes.
Add the MTX_DUPOK option to the channel mutexes and change the locking
sequence to always lock the parent channel before its children to avoid
the possibility of deadlock.
Actually implement locking assertions for the channel mutexes and fix
the problems found by the resulting assertion violations.
Clean up the locking code in dsp_ioctl().
Allocate the channel buffers using the malloc() M_WAITOK option instead
of M_NOWAIT so that buffer allocation won't fail. Drop locks across
the malloc() calls.
Add/modify KASSERTS() in attempt to detect problems early.
Abuse layering by adding a pointer to the snd_dbuf structure that points
back to the pcm_channel that owns it. This allows sndbuf_resize() to do
proper locking without having to change the its API, which is used by
the hardware drivers.
Don't dereference a NULL pointer when setting hw.snd.maxautovchans
if a hardware driver is not loaded. Noticed by Ryan Sommers
<ryans at gamersimpact.com>.
Tested by: Stefan Ehmann <shoesoft AT gmx.net>
Tested by: matk (Mathew Kanner)
Tested by: Gordon Bergling <gbergling AT 0xfce3.net>
debug.ddb_use_printf sysctl, output kernel debugger data to both the
console and kernel message buffer via printf. This fixes the case where
backtrace() went directly to the console and should help debugging greatly.
Thanks to Ian Dowse for the work, minor edits or any bugs are by myself.
Submitted by: iedowse
return an error value that made Write_Disk() abort. While on the
subject, improve the initialization of the error variable in read_gpt()
and update_gpt() even though nothing was broken there.
and NgAllocRecvData(), that dynamically allocate buffer for a binary
message, an ascii message, and a data packet, respectively. The size
of the allocated buffer is equal to the socket's receive buffer size
to guarantee that a message or a data packet is not truncated.
- Get rid of the static size buffer in NgSendAsciiMsg().
OK'ed by: archie, julian
the proc lock only if we actually need to perform a stop. This
avoids two locks and unlocks of the process lock each system call,
and wins me about 20% on a simply system call test (getuid(),
which would otherwise require no locking). This also has a net
improvement of about 10MB/s on some of the SMP bandwidth tests
I'm running.
Reviewed by: jhb
- malloc() returns a void* and does not need a cast
- when called with M_WAITOK, malloc() can not return NULL so don't
check for that case. The result of the check was bogus anyway since
it would leave the interface broken.
