They provided little benefit (if any) and they caused some problems
in OpenOffice, at least in post-KSE -current and perhaps in other
environments too. The nanosleep calls prevented the profiling timer
from advancing during the spinloops, thereby preventing the thread
scheduler from ever pre-empting the spinning thread. Alexander
Kabaev diagnosed this problem, Martin Blapp helped with testing,
and Matt Dillon provided some helpful suggestions.
This is a short-term fix for a larger problem. The use of spinlocking
isn't guaranteed to work in all cases. For example, if the spinning
thread has higher priority than all other threads, it may never be
pre-empted, and the thread holding the lock may never progress far
enough to release the lock. On the other hand, spinlocking is the
only locking that can work with an arbitrary unknown threads package.
I have some ideas for a much better fix in the longer term. It
would eliminate all locking inside the dynamic linker by making it
safe for symbol lookups and lazy binding to proceed in parallel
with a call to dlopen or dlclose. This means that the only mutual
exclusion needed would be to prevent multiple simultaneous calls
to dlopen and/or dlclose. That mutual exclusion could be put into
the native pthreads library. Applications using foreign threads
packages would have to make their own arrangements to ensure that
they did not have multiple threads in dlopen and/or dlclose -- a
reasonable requirement in my opinion.
MFC after: 3 days
of the remote host (or rather, the name as mangled by realhostname_sa())
so that the process can use it to behave differently depending on the
origin on the request. We use this to implement rudimentary visibility
control on our user information.
Make sure that the child process's standard error goes through the same
NVT-ASCII filter as is applied to the standard output.
Don't attempt to call logerr() from the child since stdio is not safe in
a vforked process. Just write a message to fd 2 instead. (Ideally, the
parent would open two pipes, and siphon off our stderr to some place less
public, but I have not attempted to do so in this implementation.)
matching constraints where appropriate. This makes the dynamic
linker buildable at -O0 again.
Thanks to Bruce Evans for identifying the cause of the build
problem.
MFC after: 1 week
Untested (testing request went unanswered), but sparc64 is not expected to
cause problems. IA64 is not expected to cause problems but the patch was
slightly more complex so the possibility exists.
Approved by: jdp
goto target was so the cache could be freed. So free the cache after
done: rather then before done: (!)
Submitted by: Gavin Atkinson <gavin@ury.york.ac.uk>
Martin Blapp determined that the elf dynamic loader was at fault. In
particular, the loader uses alloca() to allocate a symbol cache on the
stack. Normally this would work just fine, but if the loader is called
from a threaded program and the object being loaded is fairly large the
alloca() can blow away the thread stack and effect other nearby thread
stacks as well. My testing showed that the symbol cache can be as large
as 250KBytes during the openoffice port build and install sequence. Martin
was able to work around the problem by disabling the symbol cache
(cache = NULL;). However, this solution is not adequate for commit because
it can cause an enormous cpu burden for applications which do a lot of
dynamic loading (e.g. like konqueror).
The solution is to use anonymous mmap() to temporarily allocate space to
hold the symbol cache. In testing I found that replacing the alloca()
with mmap() has no observable degredation in performance.
It should be noted that this bug does not necessarily cause an immediate
crash but can instead result in long term corruption and instability in
applications that load modules from threads. The bug is almost certainly
responsible for some of the instabilities found in konqueror, for example,
and possibly netscape too.
Sleuthing work by: Martin Blapp <mb@imp.ch>
X-MFC after: Before or after the 4.6 release depending on the release engineers
can then end up not properly clearing wtmp/utmp entries.
PR: bin/37934
Submitted by: Sandeep Kumar <skumar@juniper.net>
Reviewed by: markm
MFC after: 2 weeks
o Set st_shndx for sym_zero to SHN_UNDEF instead of SHN_ABS.
This gives us something to reliably test against.
o For weak references to undefined sysmbols (as indicated by
having st_shndx equals SHN_UNDEF) in the context of OPDs,
the address of the OPD is to be zero, not the address of
the function it contains.
o For weak references to undefined symbols in all other cases
(only DIR64LSB at this time), the actual relocated value is
to be zero, not the value prior to relocating.
Roughly speaking, weak references to undefined symbols are no-ops.
Tested on: i386, ia64
relocation identifies the symbol to which we need to bind. This
solves a problem seen on ia64 where the symbol hash table does not
contain local symbols and thus resulted in unresolved symbols.
Tested on: alpha, i386, ia64
with a back off. This was discovered when Luigi sent me code to
handle this for Etherboot. The Etherboot patch worked okay but
FreeBSD's tftpd had trouble handling it and would fail to transfer
the file since it would abort on send and not retry.
Submitted by: luigi
MFC after: 1 week
objects were not being correctly set to zero. Instead, the function
descriptor pointer was set to the load address of the .so object. This
caused gcc generated binaries to segfault on exit when crtbegin.asm's
_fini code tested the __cxa_finalize() function pointer for zero.
This is a bit of a hack because of a problem nearby workaround for
find_symdef and its quirks (failures) for local symbols. This still
needs to be fixed.
returns off_t in yylval.u.o. REST is the only user of yylval.u.o at the
moment.
NB: seems lukemftpd has the same bug.
PR: misc/28629
Reviewed by: ru
Approved by: ru
MFC after: 1 month
