This patch introduces two new convenience functions to set the default
thread attributes used for creating threads. This allows a programmer
to set the default thread attributes just once in a process and then
run pthread_create without additional attributes.
Resolves BZ #15618.
pthread_attr_getaffinity_np may write beyond bounds of the input
cpuset buffer if the size of the input buffer is smaller than the
buffer present in the input pthread attributes. Fix is to copy to the
extent of the minimum of the source and the destination.
This reverts the change that allows the POSIX Thread default stack size
to be changed by the environment variable
GLIBC_PTHREAD_DEFAULT_STACKSIZE. It has been requested that more
discussion happen before this change goes into 2.18.
[BZ #14652]
When a thread waiting in pthread_cond_wait with a PI mutex is
cancelled after it has returned successfully from the futex syscall
but just before async cancellation is disabled, it enters its
cancellation handler with the mutex held and simply calling a
mutex_lock again will result in a deadlock. Hence, it is necessary to
see if the thread owns the lock and try to lock it only if it doesn't.
[BZ #14417]
A futex call with FUTEX_WAIT_REQUEUE_PI returns with the mutex locked
on success. If such a successful thread is pipped to the cond_lock by
another spuriously woken waiter, it could be sent back to wait on the
futex with the mutex lock held, thus causing a deadlock. So it is
necessary that the thread relinquishes the mutex before going back to
sleep.
[BZ #14477]
Add an additional entry in the exception table to jump to
__condvar_w_cleanup2 instead of __condvar_w_cleanup for PI mutexes
when %ebx contains the address of the futex instead of the condition
variable.
When rlimit is small enough to be used as the stacksize to be returned
in pthread_getattr_np, cases where a stack is made executable due to a
DSO load get stack size that is larger than what the kernel
allows. This is because in such a case the stack size does not account
for the pages that have auxv and program arguments.
Additionally, the stacksize for the process derived from this should
be truncated to align to page size to avoid going beyond rlimit.
There is nothing in the POSIX specification to disallow a
single-threaded program from cancelling itself, so we forcibly enable
multiple_threads to allow the next available cancellation point in the
thread to run.
Also added additional tests to cover various cancellation scenarios.
At least the Linux kernel provides field where the kernel originally
stores the command which is executed by the thread. The value can
subsequently be overwritten. The added functions allow to do that for
threads, providing and abstraction around the syscalls or /proc file
system accesses needed.
The kernel from 2.3.31 on supports the rt_tgsigqueueinfo syscall.
Use it to implement the non-standard extension which, like
sigqueue, can pass additional data to the receiving thread.
