From ba74a42cee90c9a4425188a021b6ad8ba80b9468 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sat, 16 Feb 2019 10:13:31 -0500 Subject: [PATCH] rewrite pthread_key_delete to use global thread list with the availability of the thread list, there is no need to mark tsd key slots dirty and clean them up only when a free slot can't be found. instead, directly iterate threads and clear any value associated with the key being deleted. no synchronization is necessary for the clearing, since there is no way the slot can be accessed without having synchronized with the creation of a new key occupying the same slot, which is already sequenced after and synchronized with the deletion of the old key. --- src/thread/pthread_key_create.c | 80 ++++++++------------------------- src/thread/pthread_key_delete.c | 14 ------ 2 files changed, 19 insertions(+), 75 deletions(-) delete mode 100644 src/thread/pthread_key_delete.c diff --git a/src/thread/pthread_key_create.c b/src/thread/pthread_key_create.c index 0903d48f..da1fb116 100644 --- a/src/thread/pthread_key_create.c +++ b/src/thread/pthread_key_create.c @@ -13,49 +13,17 @@ static void nodtor(void *dummy) { } -static void dirty(void *dummy) +static void dummy_0(void) { } -struct cleanup_args { - pthread_t caller; - int ret; -}; - -static void clean_dirty_tsd_callback(void *p) -{ - struct cleanup_args *args = p; - pthread_t self = __pthread_self(); - pthread_key_t i; - for (i=0; itsd[i]) - self->tsd[i] = 0; - } - /* Arbitrary choice to avoid data race. */ - if (args->caller == self) args->ret = 0; -} - -static void dummy2(void (*f)(void *), void *p) -{ -} - -weak_alias(dummy2, __pthread_key_delete_synccall); - -static int clean_dirty_tsd(void) -{ - struct cleanup_args args = { - .caller = __pthread_self(), - .ret = EAGAIN - }; - __pthread_key_delete_synccall(clean_dirty_tsd_callback, &args); - return args.ret; -} +weak_alias(dummy_0, __tl_lock); +weak_alias(dummy_0, __tl_unlock); int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *)) { pthread_key_t j = next_key; pthread_t self = __pthread_self(); - int found_dirty = 0; /* This can only happen in the main thread before * pthread_create has been called. */ @@ -70,40 +38,29 @@ int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *)) keys[next_key = *k = j] = dtor; pthread_rwlock_unlock(&key_lock); return 0; - } else if (keys[j] == dirty) { - found_dirty = 1; } } while ((j=(j+1)%PTHREAD_KEYS_MAX) != next_key); - /* It's possible that all slots are in use or __synccall fails. */ - if (!found_dirty || clean_dirty_tsd()) { - pthread_rwlock_unlock(&key_lock); - return EAGAIN; - } - - /* If this point is reached there is necessarily a newly-cleaned - * slot to allocate to satisfy the caller's request. Find it and - * mark any additional previously-dirty slots clean. */ - for (j=0; jtsd[k] = 0; + while ((td=td->next)!=self); + __tl_unlock(); + __restore_sigs(&set); + pthread_rwlock_wrlock(&key_lock); - keys[k] = dirty; + keys[k] = 0; pthread_rwlock_unlock(&key_lock); + return 0; } @@ -118,7 +75,7 @@ void __pthread_tsd_run_dtors() void *val = self->tsd[i]; void (*dtor)(void *) = keys[i]; self->tsd[i] = 0; - if (val && dtor && dtor != nodtor && dtor != dirty) { + if (val && dtor && dtor != nodtor) { pthread_rwlock_unlock(&key_lock); dtor(val); pthread_rwlock_rdlock(&key_lock); @@ -129,3 +86,4 @@ void __pthread_tsd_run_dtors() } weak_alias(__pthread_key_create, pthread_key_create); +weak_alias(__pthread_key_delete, pthread_key_delete); diff --git a/src/thread/pthread_key_delete.c b/src/thread/pthread_key_delete.c deleted file mode 100644 index 012fe2da..00000000 --- a/src/thread/pthread_key_delete.c +++ /dev/null @@ -1,14 +0,0 @@ -#include "pthread_impl.h" -#include "libc.h" - -void __pthread_key_delete_synccall(void (*f)(void *), void *p) -{ - __synccall(f, p); -} - -int __pthread_key_delete(pthread_key_t k) -{ - return __pthread_key_delete_impl(k); -} - -weak_alias(__pthread_key_delete, pthread_key_delete); -- 2.25.1