Assume that Thread 1 waits to acquire a robust mutex using futexes to
block (and thus sets the FUTEX_WAITERS flag), and is unblocked when this
mutex is released. If Thread 2 concurrently acquires the lock and is
killed, Thread 1 can recover from the died owner but fail to restore the
FUTEX_WAITERS flag. This can lead to a Thread 3 that also blocked using
futexes at the same time as Thread 1 to not get woken up because
FUTEX_WAITERS is not set anymore.
The fix for this is to ensure that we continue to preserve the
FUTEX_WAITERS flag whenever we may have set it or shared it with another
thread. This is the same requirement as in the algorithm for normal
mutexes, only that the robust mutexes need additional handling for died
owners and thus preserving the FUTEX_WAITERS flag cannot be done just in
the futex slowpath code.
[BZ #20973]
* nptl/pthread_mutex_lock.c (__pthread_mutex_lock_full): Fix lost
wake-up in robust mutexes.
* nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise.
The new test driver in <support/test-driver.c> has feature parity with
the old one. The main difference is that its hooking mechanism is
based on functions and function pointers instead of macros. This
commit also implements a new environment variable, TEST_COREDUMPS,
which disables the code which disables coredumps (that is, it enables
them if the invocation environment has not disabled them).
<test-skeleton.c> defines wrapper functions so that it is possible to
use existing macros with the new-style hook functionality.
This commit changes only a few test cases to the new test driver, to
make sure that it works as expected.
This patch adds pretty printers for the following NPTL types:
- pthread_mutex_t
- pthread_mutexattr_t
- pthread_cond_t
- pthread_condattr_t
- pthread_rwlock_t
- pthread_rwlockattr_t
To load the pretty printers into your gdb session, do the following:
python
import sys
sys.path.insert(0, '/path/to/glibc/build/nptl/pretty-printers')
end
source /path/to/glibc/source/pretty-printers/nptl-printers.py
You can check which printers are registered and enabled by issuing the
'info pretty-printer' gdb command. Printers should trigger automatically when
trying to print a variable of one of the types mentioned above.
The printers are architecture-independent, and were tested on an AMD64 running
Ubuntu 14.04 and an x86 VM running Fedora 24.
In order to work, the printers need to know the values of various flags that
are scattered throughout pthread.h and pthreadP.h as enums and #defines. Since
replicating these constants in the printers file itself would create a
maintenance burden, I wrote a script called gen-py-const.awk that Makerules uses
to extract the constants. This script is pretty much the same as gen-as-const.awk,
except it doesn't cast the constant values to 'long' and is thorougly documented.
The constants need only to be enumerated in a .pysym file, which is then referenced
by a Make variable called gen-py-const-headers.
As for the install directory, I discussed this with Mike Frysinger and Siddhesh
Poyarekar, and we agreed that it can be handled in a separate patch, and shouldn't
block merging of this one.
In addition, I've written a series of test cases for the pretty printers.
Each lock type (mutex, condvar and rwlock) has two test programs, one for itself
and other for its related 'attributes' object. Each test program in turn has a
PExpect-based Python script that drives gdb and compares its output to the
expected printer's. The tests run on the glibc host, which is assumed to have
both gdb and PExpect; if either is absent the tests will fail with code 77
(UNSUPPORTED). For cross-testing you should use cross-test-ssh.sh as test-wrapper.
I've tested the printers on both native builds and a cross build using a Beaglebone
Black running Debian, with the build system's filesystem shared with the board
through NFS.
Finally, I've written a README that explains all this and more.
* INSTALL: Regenerated.
* Makeconfig: Add comments and whitespace to make the control flow
clearer.
(+link-printers-tests, +link-pie-printers-tests, CFLAGS-printers-tests,
installed-rtld-LDFLAGS, built-rtld-LDFLAGS, link-libc-rpath,
link-libc-tests-after-rpath-link, link-libc-printers-tests): New.
(rtld-LDFLAGS, rtld-tests-LDFLAGS, link-libc-tests-rpath-link,
link-libc-tests): Use the new variables as required.
* Makerules ($(py-const)): New rule.
generated: Add $(py-const).
* README.pretty-printers: New file.
* Rules (tests-printers-programs, tests-printers-out, py-env): New.
(others): Depend on $(py-const).
(tests): Depend on $(tests-printers-programs) or $(tests-printers-out),
as required. Pass $(tests-printers) to merge-test-results.sh.
* manual/install.texi: Add requirements for testing the pretty printers.
* nptl/Makefile (gen-py-const-headers, pretty-printers, tests-printers,
CFLAGS-test-mutexattr-printers.c CFLAGS-test-mutex-printers.c,
CFLAGS-test-condattr-printers.c, CFLAGS-test-cond-printers.c,
CFLAGS-test-rwlockattr-printers.c CFLAGS-test-rwlock-printers.c,
tests-printers-libs): Define.
* nptl/nptl-printers.py: New file.
* nptl/nptl_lock_constants.pysym: Likewise.
* nptl/test-cond-printers.c: Likewise.
* nptl/test-cond-printers.py: Likewise.
* nptl/test-condattr-printers.c: Likewise.
* nptl/test-condattr-printers.py: Likewise.
* nptl/test-mutex-printers.c: Likewise.
* nptl/test-mutex-printers.py: Likewise.
* nptl/test-mutexattr-printers.c: Likewise.
* nptl/test-mutexattr-printers.py: Likewise.
* nptl/test-rwlock-printers.c: Likewise.
* nptl/test-rwlock-printers.py: Likewise.
* nptl/test-rwlockattr-printers.c: Likewise.
* nptl/test-rwlockattr-printers.py: Likewise.
* scripts/gen-py-const.awk: Likewise.
* scripts/test_printers_common.py: Likewise.
* scripts/test_printers_exceptions.py: Likewise.
This change moves the main implementation of _dl_catch_error,
_dl_signal_error to libc.so, where TLS variables can be used
directly. This removes a writable function pointer from the
rtld_global variable.
For use during initial relocation, minimal implementations of these
functions are provided in ld.so. These are eventually interposed
by the libc.so implementations. This is implemented by compiling
elf/dl-error-skeleton.c twice, via elf/dl-error.c and
elf/dl-error-minimal.c.
As a side effect of this change, the static version of dl-error.c
no longer includes support for the
_dl_signal_cerror/_dl_receive_error mechanism because it is only
used in ld.so.
This patch remove the PID cache and usage in current GLIBC code. Current
usage is mainly used a performance optimization to avoid the syscall,
however it adds some issues:
- The exposed clone syscall will try to set pid/tid to make the new
thread somewhat compatible with current GLIBC assumptions. This cause
a set of issue with new workloads and usecases (such as BZ#17214 and
[1]) as well for new internal usage of clone to optimize other algorithms
(such as clone plus CLONE_VM for posix_spawn, BZ#19957).
- The caching complexity also added some bugs in the past [2] [3] and
requires more effort of each port to handle such requirements (for
both clone and vfork implementation).
- Caching performance gain in mainly on getpid and some specific
code paths. The getpid performance leverage is questionable [4],
either by the idea of getpid being a hotspot as for the getpid
implementation itself (if it is indeed a justifiable hotspot a
vDSO symbol could let to a much more simpler solution).
Other usage is mainly for non usual code paths, such as pthread
cancellation signal and handling.
For thread creation (on stack allocation) the code simplification in fact
adds some performance gain due the no need of transverse the stack cache
and invalidate each element pid.
Other thread usages will require a direct getpid syscall, such as
cancellation/setxid signal, thread cancellation, thread fail path (at
create_thread), and thread signal (pthread_kill and pthread_sigqueue).
However these are hardly usual hotspots and I think adding a syscall is
justifiable.
It also simplifies both the clone and vfork arch-specific implementation.
And by review each fork implementation there are some discrepancies that
this patch also solves:
- microblaze clone/vfork does not set/reset the pid/tid field
- hppa uses the default vfork implementation that fallback to fork.
Since vfork is deprecated I do not think we should bother with it.
The patch also removes the TID caching in clone. My understanding for
such semantic is try provide some pthread usage after a user program
issue clone directly (as done by thread creation with CLONE_PARENT_SETTID
and pthread tid member). However, as stated before in multiple discussions
threads, GLIBC provides clone syscalls without further supporting all this
semantics.
I ran a full make check on x86_64, x32, i686, armhf, aarch64, and powerpc64le.
For sparc32, sparc64, and mips I ran the basic fork and vfork tests from
posix/ folder (on a qemu system). So it would require further testing
on alpha, hppa, ia64, m68k, nios2, s390, sh, and tile (I excluded microblaze
because it is already implementing the patch semantic regarding clone/vfork).
[1] https://codereview.chromium.org/800183004/
[2] https://sourceware.org/ml/libc-alpha/2006-07/msg00123.html
[3] https://sourceware.org/bugzilla/show_bug.cgi?id=15368
[4] http://yarchive.net/comp/linux/getpid_caching.html
* sysdeps/nptl/fork.c (__libc_fork): Remove pid cache setting.
* nptl/allocatestack.c (allocate_stack): Likewise.
(__reclaim_stacks): Likewise.
(setxid_signal_thread): Obtain pid through syscall.
* nptl/nptl-init.c (sigcancel_handler): Likewise.
(sighandle_setxid): Likewise.
* nptl/pthread_cancel.c (pthread_cancel): Likewise.
* sysdeps/unix/sysv/linux/pthread_kill.c (__pthread_kill): Likewise.
* sysdeps/unix/sysv/linux/pthread_sigqueue.c (pthread_sigqueue):
Likewise.
* sysdeps/unix/sysv/linux/createthread.c (create_thread): Likewise.
* sysdeps/unix/sysv/linux/getpid.c: Remove file.
* nptl/descr.h (struct pthread): Change comment about pid value.
* nptl/pthread_getattr_np.c (pthread_getattr_np): Remove thread
pid assert.
* sysdeps/unix/sysv/linux/pthread-pids.h (__pthread_initialize_pids):
Do not set pid value.
* nptl_db/td_ta_thr_iter.c (iterate_thread_list): Remove thread
pid cache check.
* nptl_db/td_thr_validate.c (td_thr_validate): Likewise.
* sysdeps/aarch64/nptl/tcb-offsets.sym: Remove pid offset.
* sysdeps/alpha/nptl/tcb-offsets.sym: Likewise.
* sysdeps/arm/nptl/tcb-offsets.sym: Likewise.
* sysdeps/hppa/nptl/tcb-offsets.sym: Likewise.
* sysdeps/i386/nptl/tcb-offsets.sym: Likewise.
* sysdeps/ia64/nptl/tcb-offsets.sym: Likewise.
* sysdeps/m68k/nptl/tcb-offsets.sym: Likewise.
* sysdeps/microblaze/nptl/tcb-offsets.sym: Likewise.
* sysdeps/mips/nptl/tcb-offsets.sym: Likewise.
* sysdeps/nios2/nptl/tcb-offsets.sym: Likewise.
* sysdeps/powerpc/nptl/tcb-offsets.sym: Likewise.
* sysdeps/s390/nptl/tcb-offsets.sym: Likewise.
* sysdeps/sh/nptl/tcb-offsets.sym: Likewise.
* sysdeps/sparc/nptl/tcb-offsets.sym: Likewise.
* sysdeps/tile/nptl/tcb-offsets.sym: Likewise.
* sysdeps/x86_64/nptl/tcb-offsets.sym: Likewise.
* sysdeps/unix/sysv/linux/aarch64/clone.S: Remove pid and tid caching.
* sysdeps/unix/sysv/linux/alpha/clone.S: Likewise.
* sysdeps/unix/sysv/linux/arm/clone.S: Likewise.
* sysdeps/unix/sysv/linux/hppa/clone.S: Likewise.
* sysdeps/unix/sysv/linux/i386/clone.S: Likewise.
* sysdeps/unix/sysv/linux/ia64/clone2.S: Likewise.
* sysdeps/unix/sysv/linux/mips/clone.S: Likewise.
* sysdeps/unix/sysv/linux/nios2/clone.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sh/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/tile/clone.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/clone.S: Likewise.
* sysdeps/unix/sysv/linux/aarch64/vfork.S: Remove pid set and reset.
* sysdeps/unix/sysv/linux/alpha/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/arm/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/i386/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/ia64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/m68k/clone.S: Likewise.
* sysdeps/unix/sysv/linux/m68k/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/mips/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/nios2/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sh/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/tile/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/x86_64/vfork.S: Likewise.
* sysdeps/unix/sysv/linux/tst-clone2.c (f): Remove direct pthread
struct access.
(clone_test): Remove function.
(do_test): Rewrite to take in consideration pid is not cached anymore.
This patch consolidates all Linux lseek/lseek64/llseek implementation
in on on sysdeps/unix/sysv/linux/lseek{64}.c. It also removes the llseek
file and instead consolidate the LFS lseek implementation on lseek64.c
as for other LFS symbols implementations.
The general idea is:
- lseek: ABIs that not define __OFF_T_MATCHES_OFF64_T will preferable
use __NR__llseek if kernel supports it, otherwise they will use __NR_lseek.
ABIs that defines __OFF_T_MATCHES_OFF64_T won't produce any symbol.
- lseek64: ABIs with __OFF_T_MATCHES_OFF64_T will preferable use __NR_lseek
(since it will use 64-bit arguments without low/high splitting) and
__NR__llseek if __NR_lseek is not defined (for some ILP32 ports).
- llseek: files will be removed and symbols will be aliased ot lseek64.
ABI without __OFF_T_MATCHES_OFF64_T and without __NR_llseek (basically MIPS64n32
so far) are covered by building lseek with off_t as expected and lseek64
using __NR_lseek (as expected for off64_t being passed using 64-bit registers).
For this consolidation I mantained the x32 assembly specific implementation
because to correctly fix this it would required both the x32 fix for
{INLINE,INTERNAL}_SYSCALL [1] and a wrapper to correctly subscribe it to
return 64 bits instead of default 32 bits (as for times). It could a future
cleanup.
It is based on my previous {INTERNAL,INLINE}_SYSCALL_CALL macro [2],
although it is mainly for simplification.
Tested on x86_64, i686, aarch64, armhf, and powerpc64le.
* nptl/Makefile (libpthread-routines): Remove ptw-llseek and add
ptw-lseek64.
* sysdeps/unix/sysv/linux/Makefile (sysdeps_routines): Remove llseek.
* sysdeps/unix/sysv/linux/alpha/Makefile (sysdeps_routines):
Likewise.
* sysdeps/unix/sysv/linux/generic/wordsize-32/llseek.c: Remove file.
* sysdeps/unix/sysv/linux/generic/wordsize-32/lseek.c: Remove file.
* sysdeps/unix/sysv/linux/mips/mips64/llseek.c: Likewise.
* sysdeps/unix/sysv/linux/llseek.c: Remove file.
* sysdeps/unix/sysv/linux/lseek.c: New file.
* sysdeps/unix/sysv/linux/lseek64.c: Add default Linux implementation.
* sysdeps/unix/sysv/linux/mips/mips64/syscalls.list: Remove lseek and
__libc_lseek64 from auto-generation.
* sysdeps/unix/sysv/linux/wordsize-64/syscalls.list: Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/lseek64.S: New file.
[1] https://sourceware.org/ml/libc-alpha/2016-08/msg00443.html
[2] https://sourceware.org/ml/libc-alpha/2016-08/msg00646.html
Replaces calls to write on file descriptor 2 with calls to write_message,
which writes to STDOUT_FILENO (1) and properly deals with the return of
write.
In the test cases, there are writes to stdout which do not check the result
value. This patch replaces such occurrences with calls to write_message,
which properly deals with the unused result.
Tested for powerpc64le.
This patch uses the libc_ifunc macro to create already existing ifunc functions
longjmp_ifunc, siglongjmp_ifunc if HAVE_IFUNC is defined.
The s390 pt-longjmp.c includes the common pt-longjmp.c and uses strong_alias
to create the longjmp, siglongjmp symbols for glibc version 2.19.
ChangeLog:
* nptl/pt-longjmp.c (DEFINE_LONGJMP): Use libc_ifunc macro.
* sysdeps/unix/sysv/linux/s390/pt-longjmp.c (longjmp, siglongjmp):
Use strong_alias to create symbols for glibc verison 2.19.
This patch uses the libc_ifunc macro to create already existing ifunc functions
vfork_ifunc and __vfork_ifunc if HAVE_IFUNC is defined.
ChangeLog:
* nptl/pt-vfork.c (DEFINE_VFORK): Use libc_ifunc macro.
This patch uses the libc_ifunc macro to create already existing ifunc function
system_ifunc if HAVE_IFUNC is defined.
ChangeLog:
* nptl/pt-system.c (system_ifunc): Use libc_ifunc macro.
An earlier fix for TLS dropped early initialization of DTV entries for
modules using static TLS, leaving it for __tls_get_addr to set them
up. That worked on platforms that require the GD access model to be
relaxed to LE in the main executable, but it caused a regression on
platforms that allow GD in the main executable, particularly in
statically-linked programs: they use a custom __tls_get_addr that does
not update the DTV, which fails when the DTV early initialization is
not performed.
In static programs, __libc_setup_tls performs the DTV initialization
for the main thread, but the DTV of other threads is set up in
_dl_allocate_tls_init, so that's the fix that matters.
Restoring the initialization in the remaining functions modified by
this patch was just for uniformity. It's not clear that it is ever
needed: even on platforms that allow GD in the main executable, the
dynamically-linked version of __tls_get_addr would set up the DTV
entries, even for static TLS modules, while updating the DTV counter.
for ChangeLog
[BZ #19826]
* elf/dl-tls.c (_dl_allocate_tls_init): Restore DTV early
initialization of static TLS entries.
* elf/dl-reloc.c (_dl_nothread_init_static_tls): Likewise.
* nptl/allocatestack.c (init_one_static_tls): Likewise.
This patch correctly enable and disable asynchronous cancellation on
Linux posix_spawn. Current code invert the logic by enabling and
disabling instead. It also adds a new test to check if posix_spawn
is not a cancellation entrypoint.
Checked on x86_64, i686, powerpc64le, and aarch64.
* nptl/Makefile (tests): Add tst-exec5.
* nptl/tst-exec5.c: New file.
* sysdeps/unix/sysv/linux/spawni.c (__spawni): Correctly enable and disable
asynchronous cancellation.
Current sparc32 sem_init and default one only differ on sem.newsem.pad
initialization. This patch removes sparc32 and sparc32v9 sem_init arch
specific implementation and set sparc32 to use nptl default one.
The default implementation sets the required sem.newsem.pad to 0 (which
is ununsed in other architectures).
I checked on i686 and a sparc32v9 build.
* nptl/sem_init.c (sem_init): Init pad value to 0.
* sysdeps/sparc/sparc32/sem_init.c: Remove file.
* sysdeps/sparc/sparc32/sparcv9/sem_init.c: Likewise.
This patch fixes both sem_wait and sem_timedwait cancellation point for
uncontended case. In this scenario only atomics are involved and thus
the futex cancellable call is not issue and a pending cancellation signal
is not handled.
The fix is straighforward by calling pthread_testcancel is both function
start. Although it would be simpler to call CANCELLATION_P directly, I
decided to add an internal pthread_testcancel alias and use it to export
less internal implementation on such function. A possible change on
how pthread_testcancel is internally implemented would lead to either
continue to force use CANCELLATION_P or to adjust its every use.
GLIBC testcase also does have tests for uncontended cases, test-cancel12
and test-cancel14.c, however both are flawed by adding another
cancellation point just after thread pthread_cleanup_pop:
47 static void *
48 tf (void *arg)
49 {
50 pthread_cleanup_push (cleanup, NULL);
51
52 int e = pthread_barrier_wait (&bar);
53 if (e != 0 && e != PTHREAD_BARRIER_SERIAL_THREAD)
54 {
55 puts ("tf: 1st barrier_wait failed");
56 exit (1);
57 }
58
59 /* This call should block and be cancelable. */
60 sem_wait (&sem);
61
62 pthread_cleanup_pop (0);
63
64 puts ("sem_wait returned");
65
66 return NULL;
67 }
So sem_{timed}wait does not act on cancellation, pthread_cleanup_pop executes
'cleanup' and then 'puts' acts on cancellation. Since pthread_cleanup_pop
removed the clean-up handler, it will ran only once and thus it won't accuse
an error to indicate sem_wait has not acted on the cancellation signal.
This patch also fixes this behavior by removing the cancellation point 'puts'.
It also adds some cleanup on all sem_{timed}wait cancel tests.
It partially fixes BZ #18243. Checked on x86_64.
[BZ #18243]
* nptl/pthreadP.h (__pthread_testcancel): Add prototype and hidden_proto.
* nptl/pthread_testcancel.c (pthread_cancel): Add internal aliais
definition.
* nptl/sem_timedwait.c (sem_timedwait): Add cancellation check for
uncontended case.
* nptl/sem_wait.c (__new_sem_wait): Likewise.
* nptl/tst-cancel12.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
* nptl/tst-cancel13.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
* nptl/tst-cancel14.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
* nptl/tst-cancel15.c (cleanup): Remove wrong cancellation point.
(tf): Fix check for uncontended case.
(do_test): Likewise.
This patch changes sem_open to not act as a cancellation point.
Cancellation is disable at start and reenable in function exit.
It fixes BZ #15765.
Tested on x86_64 and i686.
[BZ #15765]
* nptl/Makefile (tests): Add tst-sem16.
* nptl/tst-sem16.c: New file.
* nptl/sem_open.c (sem_open): Disable asynchronous cancellation.
Current sparc32 sem_open and default one only differ on:
1. Default one contains a 'futex_supports_pshared' check.
2. sem.newsem.pad is initialized to zero.
This patch removes sparc32 and sparc32v9 sem_open arch specific
implementation and instead set sparc32 to use nptl default one.
Using 1. is fine since it should always evaluate 0 for Linux
(an optimized away by the compiler). Adding 2. to default
implementation should be ok since 'pad' field is used mainly
on sparc32 code.
I checked on i686 and checked a sparc32v9 build.
* nptl/sem_open.c (sem_open): Init pad value to 0.
* sysdeps/sparc/sparc32/sem_open.c: Remove file.
* sysdeps/sparc/sparc32/sparcv9/sem_open.c: Likewise.
Nothing depends on the PTW macro anymore, so the mechanism to define
PTW for recompliations of libc routines is no longer needed. The
source files are still recompiled for the nptl directory, just without
the “ptw-” prefix.
(Reducing the number of pattern rules in sysd-rules is critical for
improving make performance.)
Existing interposed mallocs do not define the glibc-internal
fork callbacks (and they should not), so statically interposed
mallocs lead to link failures because the strong reference from
fork pulls in glibc's malloc, resulting in multiple definitions
of malloc-related symbols.
Before this change, several tests did not detect early deadlocks
because they used SIGALRM as the expected signal, and they ran
for the full default TIMEOUT seconds.
This commit adds a new delayed_exit function to the test skeleton,
along with several error-checking wrappers to pthread functions.
Additional error checking is introduced into several tests.
It turns out that due to the reduced stack size in tst-tls3 and the
(fixed) default stack cache size, allocated TLS variables are never
freed, so the test coverage for tst-tls3-malloc is less than complete.
This change increases the thread stack size for tst-tls3-malloc only,
to make sure thread stacks and TLS variables are freed.
Instead, call malloc and explicitly align the pointer.
There is no external location to store the original (unaligned)
pointer, and this commit increases the allocation size to store
the pointer at a fixed location relative to the TCB pointer.
The manual alignment means that some space goes unused which
was previously made available for subsequent allocations.
However, in the TLS_DTV_AT_TP case, the manual alignment code
avoids aligning the pre-TCB to the TLS block alignment. (Even
while using memalign, the allocation had some unused padding
in front.)
This concludes the removal of memalign calls from the TLS code,
and the new tst-tls3-malloc test verifies that only core malloc
routines are used.
Instead of a flag which indicates the pointer can be freed, dtv_t
now includes the pointer which should be freed. Due to padding,
the size of dtv_t does not increase.
To avoid using memalign, the new allocate_dtv_entry function
allocates a sufficiently large buffer so that a sub-buffer
can be found in it which starts with an aligned pointer. Both
the aligned and original pointers are kept, the latter for calling
free later.
This reverts commit 62ce266b0b.
The change is not mature enough because it needs the following fixes:
1. Redirect test output to a file like other tests
2. Eliminate the need to use a .gdbinit because distributions will
break without it. I should have caught that but I was in too much
of a hurry to get the patch in :/
3. Feature checking during configure to determine things like minimum
required gdb version, python-pexpect version, etc. to make sure
that tests work correctly.
This patch adds pretty printers for the following NPTL types:
- pthread_mutex_t
- pthread_mutexattr_t
- pthread_cond_t
- pthread_condattr_t
- pthread_rwlock_t
- pthread_rwlockattr_t
To load the pretty printers into your gdb session, do the following:
python
import sys
sys.path.insert(0, '/path/to/glibc/build/nptl/pretty-printers')
end
source /path/to/glibc/source/pretty-printers/nptl-printers.py
You can check which printers are registered and enabled by issuing the
'info pretty-printer' gdb command. Printers should trigger automatically when
trying to print a variable of one of the types mentioned above.
The printers are architecture-independent, and were manually tested on both
the gdb CLI and Eclipse CDT.
In order to work, the printers need to know the values of various flags that
are scattered throughout pthread.h and pthreadP.h as enums and #defines. Since
replicating these constants in the printers file itself would create a
maintenance burden, I wrote a script called gen-py-const.awk that Makerules uses
to extract the constants. This script is pretty much the same as gen-as-const.awk,
except it doesn't cast the constant values to 'long' and is thorougly documented.
The constants need only to be enumerated in a .pysym file, which is then referenced
by a Make variable called gen-py-const-headers.
As for the install directory, I discussed this with Mike Frysinger and Siddhesh
Poyarekar, and we agreed that it can be handled in a separate patch, and it shouldn't
block merging of this one.
In addition, I've written a series of test cases for the pretty printers.
Each lock type (mutex, condvar and rwlock) has two test programs, one for itself
and other for its related 'attributes' object. Each test program in turn has a
PExpect-based Python script that drives gdb and compares its output to the
expected printer's. The tests run on the glibc host, which is assumed to have
both gdb and PExpect; if either is absent the tests will fail with code 77
(UNSUPPORTED). For cross-testing you should use cross-test-ssh.sh as test-wrapper.
I've tested the printers on both a native build and a cross build using a Beaglebone
Black, with the build system's filesystem shared with the board through NFS.
Finally, I've written a README that explains all this and more.
Hopefully this should be good to go in now. Thanks.
ChangeLog:
2016-07-04 Martin Galvan <martin.galvan@tallertechnologies.com>
* Makeconfig (build-hardcoded-path-in-tests): Set to 'yes' for shared builds
if tests-need-hardcoded-path is defined.
(all-subdirs): Add pretty-printers.
* Makerules ($(py-const)): New rule.
* Rules (others): Add $(py-const), if defined.
* nptl/Makefile (gen-py-const-headers): Define.
* nptl/nptl-printers.py: New file.
* nptl/nptl_lock_constants.pysym: Likewise.
* pretty-printers/Makefile: Likewise.
* pretty-printers/README: Likewise.
* pretty-printers/test-condvar-attributes.c: Likewise.
* pretty-printers/test-condvar-attributes.p: Likewise.
* pretty-printers/test-condvar-printer.c: Likewise.
* pretty-printers/test-condvar-printer.py: Likewise.
* pretty-printers/test-mutex-attributes.c: Likewise.
* pretty-printers/test-mutex-attributes.py: Likewise.
* pretty-printers/test-mutex-printer.c: Likewise.
* pretty-printers/test-mutex-printer.py: Likewise.
* pretty-printers/test-rwlock-attributes.c: Likewise.
* pretty-printers/test-rwlock-attributes.py: Likewise.
* pretty-printers/test-rwlock-printer.c: Likewise.
* pretty-printers/test-rwlock-printer.py: Likewise.
* pretty-printers/test_common.py: Likewise.
* scripts/gen-py-const.awk: Likewise.
In Linux/ARM environment, a robust mutex can't catch the timeout result
when it is already owned by other thread and requests to try lock with
a specific time value(pthread_mutex_timedlock). The futex already returns
the ETIMEDOUT result but there is no check the return value and it makes
a deadlock.
* nptl/lowlevelrobustlock.c: Implement ETIMEDOUT logic.
This patch adds early cancel test for open syscall through a FIFO
(thus makign subsequent call to open block until the other end is
also opened).
It also cleanup the sigpause tests by using sigpause along with
SIGINT instead of __xpg_sigpause and SIGCANCEL. Since the idea
is just to test the cancellation handling there is no need to expose
internal glibc implementation details to the test through pthreadP.h
inclusion.
Tested x86_64.
* nptl/tst-cancel4-common.c (do_test): Add temporary fifo creation.
* nptl/tst-cancel4-common.h (fifoname): New variable.
(fifofd): Likewise.
(cl_fifo): New function.
* nptl/tst-cancel4.c (tf_sigpause): Replace SIGCANCEL usage by
SIGINT.
(tf_open): Add early cancel test.
tst-cleanupx4 is linked with tst-cleanupx4.o and tst-cleanup4aux.o.
Since tst-cleanupx4.o is compiled from tst-cleanup4.c with -fexceptions,
tst-cleanup4aux.c should also be compiled with -fexceptions.
Tested on x86-64 and i686.
[BZ #18645]
* nptl/Makefile (extra-test-objs): Add tst-cleanupx4aux.o.
(test-extras): Add tst-cleanupx4aux.
(CFLAGS-tst-cleanupx4aux.c): New. Set to -fexceptions.
($(objpfx)tst-cleanupx4): Replace tst-cleanup4aux.o with
tst-cleanupx4aux.o.
* nptl/tst-cleanupx4aux.c: New file.
atomic_compare_and_exchange_bool_rel and
catomic_compare_and_exchange_bool_rel are removed and replaced with the
new C11-like atomic_compare_exchange_weak_release. The concurrent code
in nscd/cache.c has not been reviewed yet, so this patch does not add
detailed comments.
* nscd/cache.c (cache_add): Use new C11-like atomic operation instead
of atomic_compare_and_exchange_bool_rel.
* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
* include/atomic.h (atomic_compare_and_exchange_bool_rel,
catomic_compare_and_exchange_bool_rel): Remove.
* sysdeps/aarch64/atomic-machine.h
(atomic_compare_and_exchange_bool_rel): Likewise.
* sysdeps/alpha/atomic-machine.h
(atomic_compare_and_exchange_bool_rel): Likewise.
* sysdeps/arm/atomic-machine.h
(atomic_compare_and_exchange_bool_rel): Likewise.
* sysdeps/mips/atomic-machine.h
(atomic_compare_and_exchange_bool_rel): Likewise.
* sysdeps/tile/atomic-machine.h
(atomic_compare_and_exchange_bool_rel): Likewise.
This patch adds cancellation tests for both sendmmsg and recvmmsg
syscalls. Since for some system configuration (x86_64/i686 on
older kernels and non-Linux platforms), the tests are added as
two independent that report as unsupported if the syscall is not
presented.
Both new tests uses the already tst-cancel4.c code, which as moved
to a common tst-cancel4-common{.c,h} files.
Tested on x86_64 and i686.
* nptl/Makefile (test): Add tst-cancel4_1 and tst-cancel4_2.
* nptl/tst-cancel4-common.c: New file.
* nptl/tst-cancel4-common.h: Likewise.
* nptl/tst-cancel4.c: Move common definitions to
tst-cancel4-common.{c,h} file.
* nptl/tst-cancel4_1.c: New test.
* nptl/tst-cancel4_2.c: New test.
This patch removes __ASSUME_FUTEX_LOCK_PI usage and assumes that
kernel will correctly return if it supports or not
futex_atomic_cmpxchg_inatomic.
Current PI mutex code already has runtime support by calling
prio_inherit_missing and returns ENOTSUP if the futex operation fails
at initialization (it issues a FUTEX_UNLOCK_PI futex operation).
Also, current minimum supported kernel (v3.2) will return ENOSYS if
futex_atomic_cmpxchg_inatomic is not supported in the system:
kernel/futex.c:
2628 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
2629 u32 __user *uaddr2, u32 val2, u32 val3)
2630 {
2631 int ret = -ENOSYS, cmd = op & FUTEX_CMD_MASK;
[...]
2667 case FUTEX_UNLOCK_PI:
2668 if (futex_cmpxchg_enabled)
2669 ret = futex_unlock_pi(uaddr, flags);
[...]
2686 return ret;
2687 }
The futex_cmpxchg_enabled is initialized by calling cmpxchg_futex_value_locked,
which calls futex_atomic_cmpxchg_inatomic.
For ARM futex_atomic_cmpxchg_inatomic will be either defined (if both
CONFIG_CPU_USE_DOMAINS and CONFIG_SMP are not defined) or use the
default generic implementation that returns ENOSYS.
For m68k is uses the default generic implementation.
For mips futex_atomic_cmpxchg_inatomic will return ENOSYS if cpu has no
'cpu_has_llsc' support (defined by each chip supporte inside kernel).
For sparc, 32-bit kernel will just use default generic implementation,
while 64-bit kernel has support.
Tested on ARM (v3.8 kernel) and x86_64.
* nptl/pthread_mutex_init.c [__ASSUME_FUTEX_LOCK_PI]
(prio_inherit_missing): Remove define.
* sysdeps/unix/sysv/linux/arm/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
* sysdeps/unix/sysv/linux/kernel-features.h (__ASSUME_FUTEX_LOCK_PI):
Likewise.
* sysdeps/unix/sysv/linux/m68k/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
* sysdeps/unix/sysv/linux/mips/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
* sysdeps/unix/sysv/linux/sparc/kernel-features.h
(__ASSUME_FUTEX_LOCK_PI): Likewise.
After some discussion in libc-alpha about this POSIX compliance fix, I see
that GLIBC should indeed revert back to previous definition of msghdr and
cmsghdr and implementation of sendmsg, recvmsg, sendmmsg, recvmmsg due some
reasons:
* The possible issue where the syscalls wrapper add the compatibility
layer is quite limited in scope and range. And kernel current
also add some limits to the values on the internal msghdr and
cmsghdr fields:
- msghdr::msg_iovlen larger than UIO_MAXIOV (1024) returns
EMSGSIZE.
- msghdr::msg_controllen larger than INT_MAX returns ENOBUFS.
* There is a small performance hit for recvmsg/sendmsg/recmmsg which
is neglectable, but it is a big hit for sendmmsg since now instead
of calling the syscall for the packed structure, GLIBC is calling
multiple sendmsg. This defeat the very existence of the syscall.
* It currently breaks libsanitizer build on GCC [1] (I fixed on compiler-rt).
However the fix is incomplete because it does add any runtime check
since libsanitizer currently does not have any facility to intercept
symbols with multiple version [2].
This, along with incorret dlsym/dlvsym return for versioned symbol due
another bug [3], makes hard to interpose versioned symbols.
Also, current approach of fixing GCC PR#71445 leads to half-baked
solutions without versioned symbol interposing.
This patch basically reverts commits 2f0dc39029, 222c2d7f43,
af7f7c7ec8. I decided to not revert abf29edd4a (Adjust
kernel-features.h defaults for recvmsg and sendmsg) mainly because it
does not really address the POSIX compliance original issue and also
adds some cleanups.
Tested on x86, i386, s390, s390x, aarch64, and powerpc64le.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71445
[2] https://github.com/google/sanitizers/issues/628
[3] https://sourceware.org/bugzilla/show_bug.cgi?id=14932
* conform/data/sys/socket.h-data (msghdr.msg_iovlen): Add xfail-.
(msghdr.msg_controllen): Likewise.
(cmsghdr.cmsg_len): Likewise.
* nptl/Makefile (libpthread-routines): Remove ptw-oldrecvmsg and
ptw-oldsendmsg.
(CFLAGS-oldrecvmsg.c): Remove rule.
(CFLAGS-oldsendmsg.c): Likewise.
(CFLAGS-recvmsg.c): Add rule.
(CFLAGS-sendmsg.c): Likewise.
* sysdeps/unix/sysv/linux/Makefile (sysdep_routines): Remove
oldrecvmsg, oldsendmsg, oldrecvmmsg, oldsendmmsg.
(CFLAGS-recvmsg.c): Remove rule.
(CFLAGS-sendmsg.c): Likewise.
(CFLAGS-oldrecvmsg.c): Likewise.
(CFLAGS-oldsendmsg.c): Likewise.
(CFLAGS-recvmmsg.c): Likewise.
* sysdeps/unix/sysv/linux/bits/socket.h (msghdr.msg_iovlen): Revert
to kernel defined interfaces.
(msghdr.msg_controllen): Likewise.
(cmsghdr.cmsg_len): Likewise.
(msghdr.__glibc_reserved1): Remove member.
(msghdr.__glibc_reserved2): Likewise.
(cmsghdr.__glibc_reserved1): Likewise.
* sysdeps/unix/sysv/linux/oldrecvmmsg.c: Remove file.
* sysdeps/unix/sysv/linux/oldrecvmsg.c: Likewise.
* sysdeps/unix/sysv/linux/oldsendmmsg.c: Likewise.
* sysdeps/unix/sysv/linux/oldsendmsg.c: Likewise.
* sysdeps/unix/sysv/linux/recvmmsg.c: Revert back to previous
version.
* sysdeps/unix/sysv/linux/recvmsg.c: Likewise.
* sysdeps/unix/sysv/linux/sendmmsg.c: Likewise.
* sysdeps/unix/sysv/linux/sendmsg.c: Likewise.
* sysdeps/unix/sysv/linux/aarch64/Versions [libc] (GLIBC_2.24):
Remove recvmsg and sendmsg.
* sysdeps/unix/sysv/linux/alpha/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/hppa/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/i386/Versions [libc] (GLIBC_2.24): Likewise.
* sysdeps/unix/sysv/linux/m68k/Versions [libc] (GLIBC_2.24): Likewise.
* sysdeps/unix/sysv/linux/microblaze/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n32/Versions
[libc] (GLIBC_2.24): Likewise.
* sysdeps/unix/sysv/linux/nios2/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/Versions
[libc] (GLIBC_2.24): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/sh/Versions [libc] (GLIBC_2.24): Likewise.
* sysdeps/unix/sysv/linux/sparc/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/tile/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/x86_64/Versions [libc] (GLIBC_2.24):
Likewise.
* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/Versions: Remove file
* sysdeps/unix/sysv/linux/x86_64/64/Versions: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n64/Versions: Likewise.
* sysdeps/unix/sysv/linux/aarch64/libc.abilist: Remove new 2.24
version for {recv,send,recm,sendm}msg.
* sysdeps/unix/sysv/linux/alpha/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/arm/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/hppa/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/i386/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/ia64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/microblaze/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/nios2/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/sh/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist: Likewise.
This patch consolidates all the pwritev{64} implementation for Linux
in only one (sysdeps/unix/sysv/linux/pwritev{64}.c). It also removes the
syscall from the auto-generation using assembly macros.
It was based on previous pwrite/pwrite64 consolidation patch. The new macro
SYSCALL_LL{64} is used to handle the offset argument and alias is created
for __ASSUME_OFF_DIFF_OFF64 in case of pread64.
Checked on x86_64, i386, aarch64, and powerpc64le.
* misc/Makefile (CFLAGS-pwritev.c): New variable: add cancellation
required flags.
(CFLAGS-pwritev64.c): Likewise.
* sysdeps/unix/sysv/linux/generic/wordsize-32/pwritev.c: Remove file.
* sysdeps/unix/sysv/linux/generic/wordsize-32/pwritev64.c: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n64/pwritev64.c: Likewise.
* sysdeps/unix/sysv/linux/wordsize-64/pwritev.c: Likewise.
* sysdeps/unix/sysv/linux/wordsize-64/pwritev64.: Likwise.
* sysdeps/unix/sysv/linux/x86_64/x32/syscalls.list (pwritev): Remove
syscall from auto-generation.
* sysdeps/unix/sysv/linux/pwritev.c: Rewrite implementation.
[WORDSIZE == 64] (pwritev64): Remove macro.
[!PWRITEV] (PWRITEV): Likewise.
[!PWRITEV] (PWRITEV_REPLACEMENT): Likewise.
[!PWRITEV] (PWRITE): Likewise.
[!PWRITEV] (OFF_T): Likewise.
[!__ASSUME_PWRITEV] (PWRITEV_REPLACEMENT): Likewise.
(LO_HI_LONG): Remove macro.
[__WORDSIZE != 64 || __ASSUME_OFF_DIFF_OFF64] (pwritev): Add function.
* sysdeps/unix/sysv/linux/pwritev64.c: Rewrite implementation.
(PWRITEV): Remove macro.
(PWRITEV_REPLACEMENTE): Likewise.
(PWRITE): Likewise.
(OFF_T): Likewise.
(pwritev64): New function.
* nptl/tst-cancel4.c (tf_writev): Add test.
This patch consolidates all the preadv{64} implementation for Linux
in only one (sysdeps/unix/sysv/linux/preadv{64}.c). It also removes the
syscall from the auto-generation using assembly macros.
It was based on previous pread/pread64 consolidation patch. The new macro
SYSCALL_LL{64} is used to handle the offset argument and alias is created
for __ASSUME_OFF_DIFF_OFF64 in case of pread64.
Checked on x86_64, i386, aarch64, and powerpc64le.
* misc/Makefile (CFLAGS-preadv.c): New variable: add cancellation
required flags.
(CFLAGS-preadv64.c): Likewise.
* sysdeps/unix/sysv/linux/generic/wordsize-32/preadv.c: Remove file.
* sysdeps/unix/sysv/linux/generic/wordsize-32/preadv64.c: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n64/preadv64.c: Likewise.
* sysdeps/unix/sysv/linux/wordsize-64/preadv.c: Likewise.
* sysdeps/unix/sysv/linux/wordsize-64/preadv64.: Likwise.
* sysdeps/unix/sysv/linux/x86_64/x32/syscalls.list (preadv): Remove
syscall from auto-generation.
* sysdeps/unix/sysv/linux/preadv.c: Rewrite implementation.
[WORDSIZE == 64] (preadv64): Remove macro.
[!PREADV] (PREADV): Likewise.
[!PREADV] (PREADV_REPLACEMENT): Likewise.
[!PREADV] (PREAD): Likewise.
[!PREADV] (OFF_T): Likewise.
[!__ASSUME_PREADV] (PREADV_REPLACEMENT): Likewise.
(LO_HI_LONG): Remove macro.
[__WORDSIZE != 64 || __ASSUME_OFF_DIFF_OFF64] (preadv): Add function.
* sysdeps/unix/sysv/linux/preadv64.c: Rewrite implementation.
(PREADV): Remove macro.
(PREADV_REPLACEMENTE): Likewise.
(PREAD): Likewise.
(OFF_T): Likewise.
(preadv64): New function.
* nptl/tst-cancel4.c (tf_preadv): Add test.
This patch fixes wrong/missing bits from the Fix {recv,send}{m}msg
standard compliance (BZ#16919) patches:
* nptl/Makefile sets CFLAGS-oldrecvfrom.c, but there's no such file as
oldrecvfrom.c. It should be oldsendmsg.c as defined by ChangeLog.
* sysdeps/unix/sysv/linux/hppa/Versions and
sysdeps/unix/sysv/linux/i386/Versions list a symbol recvms instead of
recvmsg at version GLIBC_2.24.
* nptl/Makefile (CFLAGS-oldrecvfrom.c): Remove rule.
(CFLAGS-oldsendmsg.c): Add rule.
* sysdeps/unix/sysv/linux/hppa/Versions [libc] (GLIBC_2.24):
Correct recvmsg symbol name.
* sysdeps/unix/sysv/linux/i386/Versions [libc] (GLIBC_2.24):
Likewise.
The testcase tst-cancel[x]17 ends sometimes with a segmentation fault.
This happens in one of 10000 cases. Then the real testcase has already
exited with success and returned from do_test(). The segmentation fault
occurs after returning from main in _dl_fini().
In those cases, the aio_read(&a) was not canceled because the read
request was already in progress. In the meanwhile aio_write(ap) wrote
something to the pipe and the read request is able to read the
requested byte.
The read request hasn't finished before returning from do_test().
After it finishes, it writes the return value and error code from the
read syscall to the struct aiocb a, which lies on the stack of do_test.
The stack of the subsequent function call of _dl_fini or _dl_sort_fini,
which is inlined in _dl_fini is corrupted.
In case of S390, it reads a zero and decrements it by 1:
unsigned int k = nmaps - 1;
struct link_map **runp = maps[k]->l_initfini;
The load from unmapped memory leads to the segmentation fault.
The stack corruption also happens on other architectures.
I saw them e.g. on x86 and ppc, too.
This patch adds an aio_suspend call to ensure, that the read request
is finished before returning from do_test().
ChangeLog:
* nptl/tst-cancel17.c (do_test): Wait for finishing aio_read(&a).
Error checking mutexes are not supposed to be subject to lock elision.
That would defeat the error checking nature of the mutex because lock
elision doesn't record ownership.
pthread_barrier_wait can return either PTHREAD_BARRIER_SERIAL_THREAD
or 0. Posix makes no guarantees about which thread return the unique
value.
Additionally, pthread_join was not called despite seemingly checking
for the error.
The previous barrier implementation did not fulfill the POSIX requirements
for when a barrier can be destroyed. Specifically, it was possible that
threads that haven't noticed yet that their round is complete still access
the barrier's memory, and that those accesses can happen after the barrier
has been legally destroyed.
The new algorithm does not have this issue, and it avoids using a lock
internally.
