On Sat, 09 Jul 2011 11:11:07 -0700 Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > OK, I managed to recreate the problem with current mainline. I had to > use an explicit -lstdc++ when linking test2.so. > > That gives test2.so a DT_NEEDED entry for libstdc++.so. When the > test2.so is dlopen'ed, it calls the DT_INIT_ARRAY entries for > libstdc++.so. This creates the variables generic_category_instance and > system_category_instace defined in libstdc++-v3/src/system_error.cc. It > also passes the destructor for those variables to __cxa_atexit, along > with the DSO handle for libstdc++.so. Later, when test1.so and test2.so > are dlclose'd, __cxa_finalize is called with DSO handles corresponding > to test1.so and test2.so, but __cxa_finalize is never called with the > DSO handle for libstdc++.so. So the destructors that libstdc++.so > passed to __cxa_atexit stick around. When the program exits, the exit > function calls all the remaining finalizers. At this point the > destructor runs, but libstdc++.so has been removed from the symbol map, > so the symbol resolution error occurs. It looks like the libstdc++.so > destructor is not being run because it has a reloc against a > STB_GNU_UNIQUE symbol. > > I wrote a standalone test case, attached. This test case recreates the > problem on Ubuntu Lucid running eglibc 2.11.1-0ubuntu7.8. However, the > test case passes on Fedora 14 running glibc 2.13. So it appears that > this bug has been fixed in upstream glibc. I'm not sure which change > fixes the bug, but it may be the patch for > http://sourceware.org/bugzilla/show_bug.cgi?id=12510 or > http://sourceware.org/bugzilla/show_bug.cgi?id=12511 . Thanks for the analysis, it pointed me in the right direction. It looks like STB_GNU_UNIQUE isn't the problem, but that dlclose can fail to update the symbol search list in some situations. This patch fixes all the testcases I've come across: http://sourceware.org/ml/libc-hacker/2010-05/msg00007.html -- fonts, gcc-porting, it makes no sense how it makes no sense toolchain, wxwidgets but i'll take it free anytime @ gentoo.org EFFD 380E 047A 4B51 D2BD C64F 8AA8 8346 F9A4 0662
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