with sleepable locks held from further up in the network stack, and
attempts to allocate memory to hold multicast group membership information
with M_WAITOK.
This panic was triggered specifically when an exiting routing daemon
process closes its raw sockets after joining multicast groups on them.
While we're here, comment some possible locking badness.
PR: kern/48560
this more accurately reflects what the underlying hardware of most
acpi machines that don't have children pci busses.
We still need a better way to get this information from acpi/hardware.
dereferenced directly. Toss an ifdef around it for the moment and
allow this to compile. This likely means that priority packets aren't
queued to the special high priority queue. The maintainer of this
should look into the problem.
This is likely fallout from the netgraph migration to using a more
generic meta tag from the mbug recently.
Fixes: pc98 tinerbox
and WITNESS is not built, then force all M_WAITOK allocations to
M_NOWAIT behavior (transparently). This is to be used temporarily
if wierd deadlocks are reported because we still have code paths
that perform M_WAITOK allocations with lock(s) held, which can
lead to deadlock. If WITNESS is compiled, then the sysctl is ignored
and we ask witness to tell us wether we have locks held, converting
to M_NOWAIT behavior only if it tells us that we do.
Note this removes the previous mbuf.h inclusion as well (only needed
by last revision), and cleans up unneeded [artificial] comparisons
to just the mbuf zones. The problem described above has nothing to
do with previous mbuf wait behavior; it is a general problem.
zones, and do it by direct comparison of uma_zone_t instead of strcmp.
The mbuf subsystem used to provide M_TRYWAIT/M_DONTWAIT semantics, but
this is mostly no longer the case. M_WAITOK has taken over the spot
M_TRYWAIT used to have, and for mbuf things, still may return NULL if
the code path is incorrectly holding a mutex going into mbuf allocation
functions.
The M_WAITOK/M_NOWAIT semantics are absolute; though it may deadlock
the system to try to malloc or uma_zalloc something with a mutex held
and M_WAITOK specified, it is absolutely required to not return NULL
and will result in instability and/or security breaches otherwise.
There is still room to add the WITNESS_WARN() to all cases so that
we are notified of the possibility of deadlocks, but it cannot change
the value of the "badness" variable and allow allocation to actually
fail except for the specialized cases which used to be M_TRYWAIT.
functionality by setting to a non-zero value. This is an integer, but
is treated as a boolean by the code, so clamp it to a boolean value
when set so as to avoid unnecessary bridge reinitialization if it's
changed to another value.
PR: kern/61174
Requested by: Bruce Cran
around in the vnodes surroundings when we allocate a block.
Assign a blocksize when we create a vnode, and yell a warning (and ignore it)
if we got the wrong size.
Please email all such warnings to me.
generic filesystem events to userspace. Currently only mount and unmount
of filesystems are signalled. Soon to be added, up/down status of NFS.
Introduce a sysctl node used to route requests to/from filesystems
based on filesystem ids.
Introduce a new vfsop, vfs_sysctl(mp, req) that is used as the callback/
entrypoint by the sysctl code to change individual filesystems.
ffs_mount -> bdevvp -> getnewvnode(..., mp = NULL, ...) ->
insmntqueue(vp, mp = NULL) -> KASSERT -> panic
Make getnewvnode() only call insmntqueue() if the mountpoint parameter
is not NULL.
our cached 'next vnode' being removed from this mountpoint. If we
find that it was recycled, we restart our traversal from the start
of the list.
Code to do that is in all local disk filesystems (and a few other
places) and looks roughly like this:
MNT_ILOCK(mp);
loop:
for (vp = TAILQ_FIRST(&mp...);
(vp = nvp) != NULL;
nvp = TAILQ_NEXT(vp,...)) {
if (vp->v_mount != mp)
goto loop;
MNT_IUNLOCK(mp);
...
MNT_ILOCK(mp);
}
MNT_IUNLOCK(mp);
The code which takes vnodes off a mountpoint looks like this:
MNT_ILOCK(vp->v_mount);
...
TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
...
MNT_IUNLOCK(vp->v_mount);
...
vp->v_mount = something;
(Take a moment and try to spot the locking error before you read on.)
On a SMP system, one CPU could have removed nvp from our mountlist
but not yet gotten to assign a new value to vp->v_mount while another
CPU simultaneously get to the top of the traversal loop where it
finds that (vp->v_mount != mp) is not true despite the fact that
the vnode has indeed been removed from our mountpoint.
Fix:
Introduce the macro MNT_VNODE_FOREACH() to traverse the list of
vnodes on a mountpoint while taking into account that vnodes may
be removed from the list as we go. This saves approx 65 lines of
duplicated code.
Split the insmntque() which potentially moves a vnode from one mount
point to another into delmntque() and insmntque() which does just
what the names say.
Fix delmntque() to set vp->v_mount to NULL while holding the
mountpoint lock.
to dup_sockaddr() was renamed to sodupsockaddr(), the argument was
changed from '1' to 'M_WAITOK', which changed the semantics. This
resulted in a WITNESS warning about a potential sleep while holding the
NFS server mutex. Now this will no longer happen, restoring a possible
bug present in the original code (setting RC_NAM even though the malloc
to copy the addres may fail). bde observes that the flag names here
should probably not be the same as the malloc flags for name space
reasons.
Bumped into by: kuriyama
honor the alignment and boundary constraints in the dma tag when loading
buffers. Previously, these constraints were only honored when allocating
memory via bus_dmamem_alloc(). Now, bus_dmamap_load() will automatically
use bounce buffers when needed.
Also add a set of sysctls to monitor the global busdma stats. These are:
hw.busdma.free_bpages
hw.busdma.reserved_bpages
hw.busdma.active_bpages
hw.busdma.total_bpages
hw.busdma.total_bounced
hw.busdma.total_deferred
to failing -- that is, allocations via malloc(M_WAITOK) that are required
to never fail -- if WITNESS is not defined. While everyone should be
running WITNESS, in any case, zone "Mbuf" allocations are really the only
ones that should be screwed with by this hack.
This hack is crashing people, and would continue to do so with or without
WITNESS. Things shouldn't be allocating with M_WAITOK with locks held,
but it's not okay just to always remove M_WAITOK when !WITNESS.
Reported by: Bernd Walter <ticso@cicely5.cicely.de>
FAT32 filesystems to be mounted, subject to some fairly serious limitations.
This works by extending the internal pseudo-inode-numbers generated from
the file's starting cluster number to 64-bits, then creating a table
mapping these into arbitrary 32-bit inode numbers, which can fit in
struct dirent's d_fileno and struct vattr's va_fileid fields. The mappings
do not persist across unmounts or reboots, so it's not possible to export
these filesystems through NFS. The mapping table may grow to be rather
large, and may grow large enough to exhaust kernel memory on filesystems
with millions of files.
Don't enable this option unless you understand the consequences.
- Remove recursive locking situations. Remove the MTX_RECURSE bit.
- Take the lock for any routine which is not called from within if_vr.c
itself; this includes entry points called by newbus, ifnet, callout,
ifmedia, and polling subsystems.
- Remove spl references from the code added to miibus callbacks in rev 1.60.
- Add the INTR_MPSAFE bit.
- Tidy up some assignments; locks are not needed for taking the address
of something at a known offset, for example.
- Tested on the machine this was committed from.
Tested on: UP only, !debug.mpsafenet && debug.mpsafenet
Reviewed by: rwatson
introduced a KSE_CAN_MIGRATE() invocation with one argument
missing (class). Either this is a genuine forget or it crept
in from JHB's repo where he may have modified it. If it's
the latter then it may require more attention. For now fix
the make depend.
Put some braces around the busy-wait loop in vr_rxeoc() to make the
no-op semicolon more obvious.
No functional changes.
Running on the machine I am committing from without problems.
Reviewed by: jmallett
than as one-off hacks in various other parts of the kernel:
- Add a function maybe_preempt() that is called from sched_add() to
determine if a thread about to be added to a run queue should be
preempted to directly. If it is not safe to preempt or if the new
thread does not have a high enough priority, then the function returns
false and sched_add() adds the thread to the run queue. If the thread
should be preempted to but the current thread is in a nested critical
section, then the flag TDF_OWEPREEMPT is set and the thread is added
to the run queue. Otherwise, mi_switch() is called immediately and the
thread is never added to the run queue since it is switch to directly.
When exiting an outermost critical section, if TDF_OWEPREEMPT is set,
then clear it and call mi_switch() to perform the deferred preemption.
- Remove explicit preemption from ithread_schedule() as calling
setrunqueue() now does all the correct work. This also removes the
do_switch argument from ithread_schedule().
- Do not use the manual preemption code in mtx_unlock if the architecture
supports native preemption.
- Don't call mi_switch() in a loop during shutdown to give ithreads a
chance to run if the architecture supports native preemption since
the ithreads will just preempt DELAY().
- Don't call mi_switch() from the page zeroing idle thread for
architectures that support native preemption as it is unnecessary.
- Native preemption is enabled on the same archs that supported ithread
preemption, namely alpha, i386, and amd64.
This change should largely be a NOP for the default case as committed
except that we will do fewer context switches in a few cases and will
avoid the run queues completely when preempting.
Approved by: scottl (with his re@ hat)
This class is used for detecting volume labels on file systems:
UFS, MSDOSFS (FAT12, FAT16, FAT32) and ISO9660.
It also provide native labelization (there is no need for file system).
g_label_ufs.c is based on geom_vol_ffs from Gordon Tetlow.
g_label_msdos.c and g_label_iso9660.c are probably hacks, I just found
where volume labels are stored and I use those offsets here,
but with this class it should be easy to do it as it should be done by
someone who know how.
Implementing volume labels detection for other file systems also should
be trivial.
New providers are created in those directories:
/dev/ufs/ (UFS1, UFS2)
/dev/msdosfs/ (FAT12, FAT16, FAT32)
/dev/iso9660/ (ISO9660)
/dev/label/ (native labels, configured with glabel(8))
Manual page cleanups and some comments inside were submitted by
Simon L. Nielsen, who was, as always, very helpful. Thanks!
header pointer and then casting it to the ecdt pointer. This fixes the
-O2 build. I'm unsure what changed recently to reveal this error since
this code has been unchanged for months.
