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
hatching the idea of using dc, and Giorgos (keramida) for incubating it.
This also reverses most of the previous commit which took out or
modified the text about umask stuff.
Submitted by: tegge
o Eliminate the "!mapentzone" check from vm_map_entry_create() and
vm_map_entry_dispose(). Reviewed by: tegge
o Fix white-space usage in vm_map_entry_create().
or user vm_maps. This implementation has two key benefits when compared
to vm_map_{user_,}pageable(): (1) it avoids a race condition through
the use of "in-transition" vm_map entries and (2) it eliminates lock
recursion on the vm_map.
Note: there is still an error case that requires clean up.
Reviewed by: tegge
instead, add typedefs of only gid_t, time_t, and uid_t.
o Remove an unneeded conditional that hid macros that are in the
implementation namespace and therefore don't need to be hidden when
_POSIX_SOURCE is defined.
o Adjust some conditionals for compatibility with X/Open and POSIX.
o Note missing functions getpwnam_r() and getpwuid_r().
obviously bogous return value of ad1816chan_setformat().
PR: 37932
Submitted by: Martin Kaeske <Martin.Kaeske@Stud.TU-Ilmenau.DE>
Reviewed by: hm
MFC after: 10 days
again, but also allow it in the user-specified header, too. This is far more
backwards compatible and SUSv3-happy than allowing only comma to seperate the
keywords list.
Submitted by: tjr
