Any number of readers may be in the critical section at a time and writers
are mutually exclusive to all other threads. They are a better choice when
data is rarely modified but often read and multiple threads can safely
access it for reading.
Priority inheritance is fully implemented along with other changes to the
kernel to fully support it on multiowner objects.
This also cleans up priority code in the kernel and updates some associated
structures in existing objects to the cleaner form.
Currently doesn't add the mrsw_lock.[ch] files since they're not yet
needed by anything but the supporting improvements are still useful.
This includes a typed bitarray API (bitarray.h) which is pretty basic
for now.
Change-Id: Idbe43dcd9170358e06d48d00f1c69728ff45b0e3
Reviewed-on: http://gerrit.rockbox.org/801
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested: Michael Sevakis <jethead71@rockbox.org>
errno is supposed to be thread local and we do that here in a rather
makeshift way by implementing a function that returns a pointer to
the __errno variable in the thread block.
If more serious TLS is required, perhaps it would be worthwhile
implementing it using the linker and the "__thread" storage attribute.
That's a bit overkill just for this. I'm also not liking what I saw
the compiler producing.
Change-Id: I03bc0bd6a89f6e3d6bae7653284ee01054614f9a
Reviewed-on: http://gerrit.rockbox.org/803
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested: Michael Sevakis <jethead71@rockbox.org>
No code changed, just shuffling stuff around. This should make it easier to
build only select parts kernel and use different implementations.
Change-Id: Ie1f00f93008833ce38419d760afd70062c5e22b5
