can't yet be referenced by other threads.
In microbenchmarks, this appears to reduce the cost of
pipe();close();close() on UP by 10%, and SMP by 7%. The vast majority
of the cost of allocating a pipe remains VM magic.
Suggested by: silby
calls further down the stack. If we find the cksum to be okay we pretend
that the hardware did all the work and hence keep the upper layers from
checking again.
Submitted by: Pyun YongHyeon
addend of 0. This isn't correct, and was quite easy to break by
referring to the address of an element within a structure.
However, fixing this exposed the fact that symbol lookups for
local variables were returning the base of the section they
were contained in. This case is detected by comparing the return
value from elf_lookup() to the relocbase+addend value: if it is
lesser, but greater than relocbase, then relocbase+addend is
taken to be the authoritative value.
bug reported by: gallatin
happens because the sio device was never opened and com->tp is
therefore NULL. ttygone can't swallow a NULL, so guard against that
possibility. Other places in this function make similar checks, so I
believe this is correct.
Improve child_detached a little and make it conform better to
style(9). Also, improve comment about what we'll be doing in the
future about driver_added. Soon it will be possible to kldload usb
drivers and have them attach w/o a need to disconnect/reconnect them.
Giant conditional on debug.mpsafenet in the socket soo_stat() routine,
unconditionally in vn_statfile() for VFS, and otherwise don't acquire
Giant. Accept an unlocked read in kqueue_stat(), and cryptof_stat() is
a no-op. Don't acquire Giant in fstat() system call.
Note: in fdescfs, fo_stat() is called while holding Giant due to the VFS
stack sitting on top, and therefore there will still be Giant recursion
in this case.
the data sheets leads me to believe these will just work. Those parts
with the various media readers on them may not have the required
FreeBSD drivers that will attach to the subdevices that will be seen
on some of these parts.
PCI 1515, 1530, 1620, 4520, 6411, 6420, 7410, 7510, 7610
Prompted by: Havard Eidnes
These are from the datasheets downloaded from TI's web site.
They describe the PCI[67]x[12]1 and PCI[67]x20 parts, with and without
the smartcard enabled.
kmem_alloc_pageable(). The difference between these is that an errant
memory access to the zone will be detected sooner with
kmem_alloc_nofault().
The following changes serve to eliminate the following lock-order
reversal reported by witness:
1st 0xc1a3c084 vm object (vm object) @ vm/swap_pager.c:1311
2nd 0xc07acb00 swap_pager swhash (swap_pager swhash) @ vm/swap_pager.c:1797
3rd 0xc1804bdc vm object (vm object) @ vm/uma_core.c:931
There is no potential deadlock in this case. However, witness is unable
to recognize this because vm objects used by UMA have the same type as
ordinary vm objects. To remedy this, we make the following changes:
- Add a mutex type argument to VM_OBJECT_LOCK_INIT().
- Use the mutex type argument to assign distinct types to special
vm objects such as the kernel object, kmem object, and UMA objects.
- Define a static swap zone object for use by UMA. (Only static
objects are assigned a special mutex type.)
individual file object implementations can optionally acquire Giant if
they require it:
- soo_close(): depends on debug.mpsafenet
- pipe_close(): Giant not acquired
- kqueue_close(): Giant required
- vn_close(): Giant required
- cryptof_close(): Giant required (conservative)
Notes:
Giant is still acquired in close() even when closing MPSAFE objects
due to kqueue requiring Giant in the calling closef() code.
Microbenchmarks indicate that this removal of Giant cuts 3%-3% off
of pipe create/destroy pairs from user space with SMP compiled into
the kernel.
The cryptodev and opencrypto code appears MPSAFE, but I'm unable to
test it extensively and so have left Giant over fo_close(). It can
probably be removed given some testing and review.
thread-local pointer, in practice that thread needs to be curthread. If
we're running with INVARIANTS, generate a warning if not. If we have
KDB compiled in, generate a stack trace. This doesn't fire at all in my
local test environment, but could be irritating if it fires frequently
for someone, so there will be motivation to fix things quickly when it
does.
the caller passes in a td that is curthread, and consistently pass 'td'
into vget(). Remove some bogus logic that passed in td or curthread
conditional on td being non-NULL, which seems redundant in the face of
the earlier assignment of td to curthread if td is NULL.
In devfs_symlink(), cache the passed thread in 'td' so we don't have
to keep retrieving it from the 'ap' structure, and assert that td is
curthread (since we dereference it to get thread-local td_ucred). Use
'td' in preference to curthread for later lockmgr calls, since they are
equal.
- 'savech' is only used if it is set a few lines above where
it is used, initialize it to silence warning.
- 'length' is either -1 or greater than 0, hence it is safe to cast it
to unsigned when comparing it here.
odsyntax.c:
- 'p' is assigned either (*argvp)[0] or (*argvp)[1] which both are
char *. 'num' and 'end' are assigned values based on 'p'.
Hence use char * instead of unsigned char * for these variables.
'&end' as the second argument to strtoll does not need to be casted
to char** any more.
This solves a
'dereferencing type-punned pointer will break strict-aliasing rules'
warning when compiling with -O2.
parse.c:
- 'prec' is only used when sokay == USEPREC and sokay = USEPREC
when 'prec' is assigned. Hence 'prec' is not used uninitialized,
initialize it to silence warning.
- The code involving 'nextpr' is hard to follow, but I belive
'nextpr' will not be used unless it is initialized.
Anyway, IF 'nextpr' is used uninitialized it is better to
get a consistant error (seg fault, when dereferencing a NULL pointer)
than potentially accessing some random memory.
The above changes makes hexdump WARNS=6 clean even when compiled with
-O2. Hence bump WARNS to keep it clean.
Tested by: CFLAGS='-O2 -pipe' make universe
to the PR failed, because the line skipping function is actually called
from two places in the code to do quite different things (this should
be two functions probably): in a false .if to skip to the next line
beginning with a dot and to collect .for loops. In the seconds case we
should not skip comments, because they are actually harder to handle than
we need for the .if case and should defer this to the main code.
PR: bin/25627
Submitted by: Seth Kingsley (original patch)
