another thread. We use the td_oncpu member of the other field to locate
it's associated CPU and then search the that CPU's list of spin locks
contained in its per-CPU data. This is not always safe and may in fact
panic or just not work, but it is useful in at least one case.
on a non-blocking pipe in cases where select(2) returns the file
descriptor as ready for write. This in turns causes libc_r, for
one, to busy wait in such cases.
Note: it is a quick performance fix, a more complex fix might be
required in case this turns out to have unexpected side effects.
Reviewed by: silby
MFC after: 3 days
thread's pid to make debugging easier for people who don't want to have to
use the intended tool for these panics (witness).
Indirectly prodded by: kris
a long-standing mistake in the way a portion of a pipe's KVA is
allocated. Specifically, kmem_alloc_pageable() is inappropriate
for use in the "direct" case because it allows a preceding vm map entry
and vm object to be extended to support the new KVA allocation.
However, the direct case KVA allocation should not have a backing
vm object. This is corrected by using kmem_alloc_nofault().
Submitted by: tegge (with the above explanation by me)
kernel ACL interfaces and system call names.
Break out UFS2 and FFS extattr delete and list vnode operations from
setextattr and getextattr to deleteextattr and listextattr, which
cleans up the implementations, and makes the results more readable,
and makes the APIs more clear.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
kern.file sysctl, don't return information about processes that
fail p_cansee(td, p). This prevents sockstat and related
programs from seeing file descriptors owned by processes not
in the same jail as the thread, as well as having implications
for MAC, etc.
This is a partial solution: it permits an information leak about
the number of descriptors in the sizing calculation (but this is
not new information, you can also get it from kern.openfiles),
and doesn't attempt to mask file descriptors based on the
properties of the descriptor, only the process referencing it.
However, it provides most of what you want under most
circumstances, without complicating the locking.
PR: 54211
Based on a patch submitted by: Pawel Jakub Dawidek <nick@garage.freebsd.pl>
contain the filedescriptor number on opens from userland.
The index is used rather than a "struct file *" since it conveys a bit
more information, which may be useful to in particular fdescfs and /dev/fd/*
For now pass -1 all over the place.
comes across it, it will turn into a core dump in userland instead of
a kernel panic. I had also inverted the sense of the test, so
Double pointy hat to: mtm
- Make m_prepend use m_gethdr instead of m_get where
appropriate
- Make m_copym use m_gethdr instead of m_get where
appropriate
- Add a call to m_fixhdr in m_defrag; m_defrag can't
deal with corrupted pkthdr.len counts.
MFC after: 3 days
do not clear the `sb_sel' member of the sockbuf structure
while invalidating the receive sockbuf in sorflush(), called
from soshutdown().
The panic was reproduceable from user land by attaching a knote
with EVFILT_READ filters to a socket, disabling further reads
from it using shutdown(2), and then closing it. knote_remove()
was called to remove all knotes from the socket file descriptor
by detaching each using its associated filterops' detach call-
back function, sordetach() in this case, which tried to remove
itself from the invalidated sockbuf's klist (sb_sel.si_note).
PR: kern/54331
When a signal is being delivered to process, first find a sigwait
thread to deliver, POSIX's argument is speed of delivering signal
to sigwait thread is faster than other ways. A signal in its wait
set will cause sigwait to return the signal number, a signal not
in its wait set but in not blocked by the thread also causes sigwait
to return, but sigwait returns EINTR, sigwait is oneshot operation,
only one signal can be delivered to its wait set, when a signal is
delivered to the sigwait thread, the thread's sigwait state is canceled.
an appropriate error number after a failure condition.
In particular, three of the changed statements return ESRCH for a
failed pfind(), and in also three places a non-zero return
from p_cansee() will be passed back,
Also noticed by: rwatson
1. There was a race condition between a thread unlocking
a umtx and the thread contesting it. If the unlocking
thread won the race it may try to wakeup a thread that
was not yet in msleep(). The contesting thread would then
go to sleep to await a wakeup that would never come. It's
not possible to close the race by using a lock because
calls to casuptr() may have to fault a page in from swap.
Instead, the race was closed by introducing a flag that
the unlocking thread will set when waking up a thread.
The contesting thread will check for this flag before
going to sleep. For now the flag is kept in td_flags,
but it may be better to use some other member or create
a new one because of the possible performance/contention
issues of having to own sched_lock. Thanks to jhb for
pointing me in the right direction on this one.
2. Once a umtx was contested all future locks and unlocks
were happening in the kernel, regardless of whether it
was contested or not. To prevent this from happening,
when a thread locks a umtx it checks the queue for that
umtx and unsets the contested bit if there are no other
threads waiting on it. Again, this is slightly more
complicated than it needs to be because we can't hold
a lock across casuptr(). So, the thread has to check
the queue again after unseting the bit, and reset the
contested bit if it finds that another thread has put
itself on the queue in the mean time.
3. Remove the if... block for unlocking an uncontested
umtx, and replace it with a KASSERT. The _only_ time
a thread should be unlocking a umtx in the kernel is
if it is contested.
large to huge amounts of small or medium sized receive buffers. The problem
with these situations is that they eat up the available DMA address space
very quickly when using mbufs or even mbuf clusters. Additionally this
facility provides a direct mapping between 32-bit integers and these buffers.
This is needed for devices originally designed for 32-bit systems. Ususally
the virtual address of the buffer is used as a handle to find the buffer as
soon as it is returned by the card. This does not work for 64-bit machines
and hence this mapping is needed.
multiple mutex pools with different options and sizes. Mutex pools can
be created with either the default sleep mutexes or with spin mutexes.
A dynamically created mutex pool can now be destroyed if it is no longer
needed.
Create two pools by default, one that matches the existing pool that
uses the MTX_NOWITNESS option that should be used for building higher
level locks, and a new pool with witness checking enabled.
Modify the users of the existing mutex pool to use the appropriate pool
in the new implementation.
Reviewed by: jhb
immediately after the kernel map has been sized, and is
the optimal place for the autosizing of memory allocations
which occur within the kernel map to occur.
Suggested by: bde
- Use atomic ops to update the bigpipe count
- Make the bigpipe count sysctl readable
- Remove a duplicate comparison in an if statement
- Comment two SYSCTLs.
than the shortcircuited version I had been using, which only worked
properly on i386 & amd64.
Also, change an autoscale constant to account for the more correct
kmem_map size.
Problem noticed by: mux
- Limit the total number of pipes so that we do not
exhaust all vm objects in the kernel map. When
this limit is reached, a ratelimited message will
be printed to the console.
- Put a soft limit on the amount of memory consumable
by pipes. Once the limit has been reached, all new
pipes will be limited to 4K in size, rather than the
default of 16K.
- Put a limit on the number of pages that may be used
for high speed page flipping in order to reduce the
amount of wired memory. Pipe writes that occur
while this limit is exceeded will fall back to
non-page flipping mode.
The above values are auto-tuned in subr_param.c and
are scaled to take into account both the size of
physical memory and the size of the kernel map.
These limits help to reduce the "kernel resources exhausted"
panics that could be caused by opening a large
number of pipes. (Pipes alone are no longer able
to exhaust all resources, but other kernel memory hogs
in league with pipes may still be able to do so.)
PR: 53627
Ideas / comments from: hsu, tjr, dillon@apollo.backplane.com
MFC after: 1 week
