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Aliaksei Kandratsenka
946d687d26
GL(dl_load_tls_lock) was introduced (bug 28357) to protect global and module-specific TLS state, and dl_open_worker_begin conservatively runs most of dlopen under it. The lock is also taken by pthread_create and __tls_get_addr, so work done while holding it, such as the malloc calls in _dl_find_object_update, can block unrelated threads. Hold it only for the steps that need it. Move the fallible _dl_find_object_update call, together with activate_nodelete, update_scopes, the reloc_complete probe and the libc early init call, from dl_open_worker_begin to dl_open_worker, after dl_load_tls_lock has been released. These steps run after relocation is complete and do not touch the TLS state that the lock protects. They remain serialized against other dlopen and dlclose calls by GL(dl_load_lock), which is held throughout. The RT_CONSISTENT debugger/audit checkpoint is moved into maybe_report_r_debug_consistent. It is called on the success path before initializers run, and from _dl_open for the error path, and ensures that the checkpoint is signalled exactly once. The order of events relative to libc early init, the initializers and the error cleanup is unchanged. The r_debug pointer used for the reloc_start/reloc_complete probes is now kept in struct dl_open_args. In dlclose, call _dl_find_object_dlclose for all unloaded objects in a separate loop before dl_load_tls_lock and GL(dl_load_write_lock) are taken. _dl_find_object readers are lock-free, and writers are serialized by GL(dl_load_lock), so neither lock is needed for this update. The objects are also marked as closed in the _dl_find_object data before they are unlinked and unmapped. Signed-off-by: Aliaksei Kandratsenka <alkondratenko@gmail.com> Reviewed-by: Adhemerval Zanella adhemerval.zanella@linaro.org
This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu and x86_64-gnu. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 3.2 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arc*-*-linux-gnu arm-*-linux-gnueabi csky-*-linux-gnuabiv2 hppa-*-linux-gnu i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 loongarch64-*-linux-gnu Hardware floating point, LE only. m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu or1k-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390x-*-linux-gnu riscv32-*-linux-gnu riscv64-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see https://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at https://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see https://sourceware.org/glibc/wiki/Bugzilla%20Procedures for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 1996-2015, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.