Add multi-reader, single-writer locks to kernel.

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>

1 files changed, 3 insertions, 0 deletions

diff --git a/firmware/SOURCES b/firmware/SOURCES
index 5e37892efe..584254a666 100644
--- a/firmware/SOURCES
+++ b/firmware/SOURCES
@@ -1825,6 +1825,9 @@ drivers/touchpad.c
 #ifdef HAVE_CORELOCK_OBJECT
 kernel/corelock.c
 #endif
+#if 0 /* pending dependent code */
+kernel/mrsw_lock.c
+#endif
 kernel/mutex.c
 kernel/queue.c
 #ifdef HAVE_SEMAPHORE_OBJECTS