To support stack unwinding for cancellation points, add -fexceptions flag
for them, two functions _pthread_cancel_enter and _pthread_cancel_leave
are added to let thread enter and leave a cancellatio

To support stack unwinding for cancellation points, add -fexceptions flag
for them, two functions _pthread_cancel_enter and _pthread_cancel_leave
are added to let thread enter and leave a cancellation point, it also
makes it possible that other functions can be cancellation points in
libraries without having to be rewritten in libthr.

show more ...

IFH@204581

preserve errno when processing error cases.

Also call sem_module_init in sem_close to initialize mutex
with some attributes.

Return SEM_FAILED instead of NULL, though there are same, but the
SEM_FAILED is more suitable name.
In function, sem_close(), always set errno on error.

Don't forget to use fourth argument if O_CREAT is set in argument oflag.
The fourth specifies initial value for the semaphore.

Merge from head at r201628.

# This hasn't been tested, and there are at least three bad commits
# that need to be backed out before the branch will be stable again.

More cleanup, remove _libc prefix because libthr no longer has stubs
referencing them.

Don't check has_waiters twice, inline some small functions.
performance result on my machine:
mutex Elapsed: 902115 us; per iteration: 90 ns.
semaphore Elapsed: 958780 us; per iteration: 95 ns.

Use umtx to implement process sharable semaphore, to make this work,
now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User

Use umtx to implement process sharable semaphore, to make this work,
now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User can either use mmap(MAP_SHARED) + sem_init(pshared=1) or use sem_open()
to initialize a shared semaphore.
Named semaphore uses file system and is located in /tmp directory, and its
file name is prefixed with 'SEMD', so now it is chroot or jail friendly.
In simplist cases, both for named and un-named semaphore, userland code
does not have to enter kernel to reduce/increase semaphore's count.
The semaphore is designed to be crash-safe, it means even if an application
is crashed in the middle of operating semaphore, the semaphore state is
still safely recovered by later use, there is no waiter counter maintained
by userland code.
The main semaphore code is in libc and libthr only has some necessary stubs,
this makes it possible that a non-threaded application can use semaphore
without linking to thread library.
Old semaphore implementation is kept libc to maintain binary compatibility.
The kernel ksem API is no longer used in the new implemenation.

Discussed on: threads@

show more ...

preserve errno when processing error cases.

Also call sem_module_init in sem_close to initialize mutex
with some attributes.

Return SEM_FAILED instead of NULL, though there are same, but the
SEM_FAILED is more suitable name.
In function, sem_close(), always set errno on error.

Don't forget to use fourth argument if O_CREAT is set in argument oflag.
The fourth specifies initial value for the semaphore.

Merge from head at r201628.

# This hasn't been tested, and there are at least three bad commits
# that need to be backed out before the branch will be stable again.

More cleanup, remove _libc prefix because libthr no longer has stubs
referencing them.

Don't check has_waiters twice, inline some small functions.
performance result on my machine:
mutex Elapsed: 902115 us; per iteration: 90 ns.
semaphore Elapsed: 958780 us; per iteration: 95 ns.

Use umtx to implement process sharable semaphore, to make this work,
now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User

Use umtx to implement process sharable semaphore, to make this work,
now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User can either use mmap(MAP_SHARED) + sem_init(pshared=1) or use sem_open()
to initialize a shared semaphore.
Named semaphore uses file system and is located in /tmp directory, and its
file name is prefixed with 'SEMD', so now it is chroot or jail friendly.
In simplist cases, both for named and un-named semaphore, userland code
does not have to enter kernel to reduce/increase semaphore's count.
The semaphore is designed to be crash-safe, it means even if an application
is crashed in the middle of operating semaphore, the semaphore state is
still safely recovered by later use, there is no waiter counter maintained
by userland code.
The main semaphore code is in libc and libthr only has some necessary stubs,
this makes it possible that a non-threaded application can use semaphore
without linking to thread library.
Old semaphore implementation is kept libc to maintain binary compatibility.
The kernel ksem API is no longer used in the new implemenation.

Discussed on: threads@

show more ...