newlib: add an option to combine some locks.

The locks are using a bit of the limited ram. It's probably fine to combine some
of these to use the same mutex, and this patch does so for the set initialized
early. The file locks will still be separate, and dynamically created, so a
thread blocking on them will not deadlock all uses of newlib that need a lock.
This commit is contained in:
Our Air Quality 2017-12-27 13:45:11 +11:00
parent a922ea0383
commit 3b2e0773ca

View file

@ -239,6 +239,10 @@ extern _lock_t __sinit_recursive_mutex;
void init_newlib_locks()
{
_lock_init(&__arc4random_mutex);
#if 0
/* Separate mutex for each lock.
* Each mutex uses about 96 bytes which adds up. */
_lock_init(&__at_quick_exit_mutex);
//_lock_init(&__dd_hash_mutex);
_lock_init(&__tz_mutex);
@ -248,6 +252,21 @@ void init_newlib_locks()
_lock_init_recursive(&__malloc_recursive_mutex);
_lock_init_recursive(&__sfp_recursive_mutex);
_lock_init_recursive(&__sinit_recursive_mutex);
#else
/* Reuse the same mutex for all these, reducing memory usage. Newlib
* will still allocate other locks dynamically and some of those need
* to be separate such as the file lock where a thread might block with
* them held. */
__at_quick_exit_mutex = __arc4random_mutex;
//__dd_hash_mutex = __arc4random_mutex;
__tz_mutex = __arc4random_mutex;
__atexit_recursive_mutex = __arc4random_mutex;
__env_recursive_mutex = __arc4random_mutex;
__malloc_recursive_mutex = __arc4random_mutex;
__sfp_recursive_mutex = __arc4random_mutex;
__sinit_recursive_mutex = __arc4random_mutex;
#endif
locks_initialized = 1;
}