Bug 18125: Call exit after last linked context

System Internals / glibc - Carlos O'Donell [systemhalted.org] - 8 May 2015 10:29 UTC

There appears to be a discrepancy among the implementations of setcontext with regards to the function called once the last linked-to context has finished executing via setcontext.

The POSIX standard says:

If the uc_link member of the ucontext_t structure pointed to by the ucp argument is equal to 0, then this context is the main context, and the thread will exit when this context returns.


It says "exit" not "exit immediately" nor "exit without running functions registered with atexit or on_exit."

Therefore the AArch64, ARM, hppa and NIOS II implementations are wrong and no test detects it.

It is questionable if this should even be fixed or just documented that the above 4 targets are wrong. The functions are deprecated and nobody should be using them, but at the same time it silly to have cross-target differences that make it hard to port old applications from say x86_64 to AArch64.

Therefore I will ix the 4 arches, and checkin a regression test to prevent it from changing again.

https://sourceware.org/ml/libc-alpha/2015-03/msg00720.html

c92d40c Bug 18125: Call exit after last linked context.
ChangeLog | 13 +++
NEWS | 18 ++--
stdlib/Makefile | 9 +-
stdlib/tst-setcontext3.c | 138 ++++++++++++++++++++++++++
stdlib/tst-setcontext3.sh | 54 ++++++++++
sysdeps/unix/sysv/linux/aarch64/setcontext.S | 2 +-
sysdeps/unix/sysv/linux/arm/setcontext.S | 2 +-
sysdeps/unix/sysv/linux/hppa/setcontext.S | 3 +-
sysdeps/unix/sysv/linux/nios2/setcontext.S | 6 +-
9 files changed, 229 insertions(+), 16 deletions(-)

Upstream: sourceware.org

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