The commit documents the ownership rules around 'struct pthread' and
when a thread can read or write to the descriptor. With those ownership
rules in place it becomes obvious that pd->stopped_start should not be
touched in several of the paths during thread startup, particularly so
for detached threads. In the case of detached threads, between the time
the thread is created by the OS kernel and the creating thread checks
pd->stopped_start, the detached thread might have already exited and the
memory for pd unmapped. As a regression test we add a simple test which
exercises this exact case by quickly creating detached threads with
large enough stacks to ensure the thread stack cache is bypassed and the
stacks are unmapped. Before the fix the testcase segfaults, after the
fix it works correctly and completes without issue.
For a detailed discussion see:
https://www.sourceware.org/ml/libc-alpha/2017-01/msg00505.html
The support/tst-support_record_failure-2.out test attempts to run
built code even if run-built-tests = no, so failing with
build-many-glibcs.py for all architectures whose code cannot be run on
the system running the script. This patch disables the test in that
case.
Tested for x86_64 (native), and for aarch64 with build-many-glibcs.py.
* support/Makefile (tests-special): Make definition conditional on
[$(run-built-tests) = yes].
($(objpfx)tst-support_record_failure-2.out): Make rule conditional
on [$(run-built-tests) = yes].
The new functions support_record_failure records a test failure,
but does not terminate the process. The macros TEST_VERIFY
and TEST_VERIFY_EXIT check that a condition is true.
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.
