diff options
Diffstat (limited to 'toolchain/musl/patches/500-0004-restore-lock-skipping-for-processes-that-return-to-s.patch')
| -rw-r--r-- | toolchain/musl/patches/500-0004-restore-lock-skipping-for-processes-that-return-to-s.patch | 90 |
1 files changed, 0 insertions, 90 deletions
diff --git a/toolchain/musl/patches/500-0004-restore-lock-skipping-for-processes-that-return-to-s.patch b/toolchain/musl/patches/500-0004-restore-lock-skipping-for-processes-that-return-to-s.patch deleted file mode 100644 index 83a6d0247a..0000000000 --- a/toolchain/musl/patches/500-0004-restore-lock-skipping-for-processes-that-return-to-s.patch +++ /dev/null @@ -1,90 +0,0 @@ -From 8d81ba8c0bc6fe31136cb15c9c82ef4c24965040 Mon Sep 17 00:00:00 2001 -From: Rich Felker <dalias@aerifal.cx> -Date: Fri, 22 May 2020 17:45:47 -0400 -Subject: [PATCH 4/4] restore lock-skipping for processes that return to - single-threaded state - -the design used here relies on the barrier provided by the first lock -operation after the process returns to single-threaded state to -synchronize with actions by the last thread that exited. by storing -the intent to change modes in the same object used to detect whether -locking is needed, it's possible to avoid an extra (possibly costly) -memory load after the lock is taken. ---- - src/internal/libc.h | 1 + - src/malloc/malloc.c | 5 ++++- - src/thread/__lock.c | 4 +++- - src/thread/pthread_create.c | 8 ++++---- - 4 files changed, 12 insertions(+), 6 deletions(-) - ---- a/src/internal/libc.h -+++ b/src/internal/libc.h -@@ -21,6 +21,7 @@ struct __libc { - char can_do_threads; - char threaded; - char secure; -+ volatile signed char need_locks; - int threads_minus_1; - size_t *auxv; - struct tls_module *tls_head; ---- a/src/malloc/malloc.c -+++ b/src/malloc/malloc.c -@@ -26,8 +26,11 @@ int __malloc_replaced; - - static inline void lock(volatile int *lk) - { -- if (libc.threaded) -+ int need_locks = libc.need_locks; -+ if (need_locks) { - while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1); -+ if (need_locks < 0) libc.need_locks = 0; -+ } - } - - static inline void unlock(volatile int *lk) ---- a/src/thread/__lock.c -+++ b/src/thread/__lock.c -@@ -18,9 +18,11 @@ - - void __lock(volatile int *l) - { -- if (!libc.threaded) return; -+ int need_locks = libc.need_locks; -+ if (!need_locks) return; - /* fast path: INT_MIN for the lock, +1 for the congestion */ - int current = a_cas(l, 0, INT_MIN + 1); -+ if (need_locks < 0) libc.need_locks = 0; - if (!current) return; - /* A first spin loop, for medium congestion. */ - for (unsigned i = 0; i < 10; ++i) { ---- a/src/thread/pthread_create.c -+++ b/src/thread/pthread_create.c -@@ -118,8 +118,8 @@ _Noreturn void __pthread_exit(void *resu - * until the lock is released, which only happens after SYS_exit - * has been called, via the exit futex address pointing at the lock. - * This needs to happen after any possible calls to LOCK() that might -- * skip locking if libc.threads_minus_1 is zero. */ -- libc.threads_minus_1--; -+ * skip locking if process appears single-threaded. */ -+ if (!--libc.threads_minus_1) libc.need_locks = -1; - self->next->prev = self->prev; - self->prev->next = self->next; - self->prev = self->next = self; -@@ -339,7 +339,7 @@ int __pthread_create(pthread_t *restrict - ~(1UL<<((SIGCANCEL-1)%(8*sizeof(long)))); - - __tl_lock(); -- libc.threads_minus_1++; -+ if (!libc.threads_minus_1++) libc.need_locks = 1; - ret = __clone((c11 ? start_c11 : start), stack, flags, args, &new->tid, TP_ADJ(new), &__thread_list_lock); - - /* All clone failures translate to EAGAIN. If explicit scheduling -@@ -363,7 +363,7 @@ int __pthread_create(pthread_t *restrict - new->next->prev = new; - new->prev->next = new; - } else { -- libc.threads_minus_1--; -+ if (!--libc.threads_minus_1) libc.need_locks = 0; - } - __tl_unlock(); - __restore_sigs(&set); |