libc/picolibc: Use mutexes instead of semaphores for non-recursive locks
Picolibc has both recursive and non-recursive mutex uses. The bulk of the
library locking uses the global libc lock, which is a recursive mutex as
that greatly simplifies the implementation.
The only use of non-recursive mutexes is in the stdio code when dealing
with file system I/O via fopen.
Using mutexes for both APIs is valid; the assumption picolibc makes is that
the non-recursive mutexes are somehow cheaper or faster and should be
preferred. However, in Zephyr, recursive mutexes are the default and the
non-recursive locks for picolibc were implemented using semaphores.
Switch the non-recursive picolibc locks to just invoking the existing
recursive functions using mutexes. This avoids pulling in another lock
implementation, saving a bit of space.
This also lets the kernel.memory_protection.mem_map test work on
qemu_x86_tiny where the amount of memory available is 320kB and that is
nearly filled by this test case, leaving too little space for allocating
pages in the k_mem_map_unmap test.
Signed-off-by: Keith Packard <keithp@keithp.com>
1 file changed
