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-rw-r--r--linuxthreads/ChangeLog18
-rw-r--r--linuxthreads/Examples/ex18.c112
-rw-r--r--linuxthreads/Makefile2
-rw-r--r--linuxthreads/internals.h6
-rw-r--r--linuxthreads/manager.c21
-rw-r--r--linuxthreads/specific.c66
6 files changed, 206 insertions, 19 deletions
diff --git a/linuxthreads/ChangeLog b/linuxthreads/ChangeLog
index 307388b..dcc18cc 100644
--- a/linuxthreads/ChangeLog
+++ b/linuxthreads/ChangeLog
@@ -1,3 +1,21 @@
+2001-11-28 Kaz Kylheku <kaz@ashi.footprints.net>
+
+ Bugfix to pthread_key_delete. It was iterating over the thread
+ manager's linked list of threads, behind the thread manager's
+ back causing a race. The fix is to have the manager iterate over
+ the threads instead, using a new request type for doing so.
+ * internals.h (struct pthread_request): New manager request type
+ REQ_FOR_EACH_THREAD.
+ * manager.c (pthread_for_each_thread): New function.
+ (__pthread_manager): Handle new REQ_FOR_EACH_THREAD request.
+ * specific.c (struct pthread_key_delete_helper_args): New type.
+ (pthread_key_delete_helper): New static function.
+ (pthread_key_delete): Use the new thread manager
+ REQ_FOR_EACH_THREAD function to iterate over the threads and set
+ the delete key slot to a null value in each thread.
+ * Examples/ex18.c: New test.
+ * Makefile (tests): Add ex18.
+
2001-11-22 Wolfram Gloger <wg@malloc.de>
* pthread.c (pthread_onexit_process): Don't call free
diff --git a/linuxthreads/Examples/ex18.c b/linuxthreads/Examples/ex18.c
new file mode 100644
index 0000000..642f6b4
--- /dev/null
+++ b/linuxthreads/Examples/ex18.c
@@ -0,0 +1,112 @@
+/*
+ * Beat up the pthread_key_create and pthread_key_delete
+ * functions.
+ */
+
+#if 0
+#define CHATTY
+#endif
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+const int beatup_iterations = 10000;
+const int num_threads = 30;
+const int max_keys = 500;
+
+struct key_list {
+ struct key_list *next;
+ pthread_key_t key;
+};
+
+struct key_list *key_list;
+pthread_mutex_t key_lock = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * Create a new key and put it at the tail of a linked list.
+ * If the linked list grows to a certain length, delete a key from the
+ * head of * the list.
+ */
+
+static void
+beat_up(void)
+{
+ struct key_list *new = malloc(sizeof *new);
+ struct key_list **iter, *old_key = 0;
+ int key_count = 0;
+
+ if (new == 0) {
+ fprintf(stderr, "malloc failed\n");
+ abort();
+ }
+
+ new->next = 0;
+
+ if (pthread_key_create(&new->key, 0) != 0) {
+ fprintf(stderr, "pthread_key_create failed\n");
+ abort();
+ }
+
+ if (pthread_getspecific(new->key) != 0) {
+ fprintf(stderr, "new pthread_key_t resolves to non-null value\n");
+ abort();
+ }
+
+ pthread_setspecific(new->key, (void *) 1);
+
+#ifdef CHATTY
+ printf("created key\n");
+#endif
+
+ pthread_mutex_lock(&key_lock);
+
+ for (iter = &key_list; *iter != 0; iter = &(*iter)->next)
+ key_count++;
+
+ *iter = new;
+
+ if (key_count > max_keys) {
+ old_key = key_list;
+ key_list = key_list->next;
+ }
+
+ pthread_mutex_unlock(&key_lock);
+
+ if (old_key != 0) {
+#ifdef CHATTY
+ printf("deleting key\n");
+#endif
+ pthread_key_delete(old_key->key);
+ }
+}
+
+static void *
+thread(void *arg)
+{
+ int i;
+ for (i = 0; i < beatup_iterations; i++)
+ beat_up();
+ return 0;
+}
+
+int
+main(void)
+{
+ int i;
+ pthread_attr_t detached_thread;
+
+ pthread_attr_init(&detached_thread);
+ pthread_attr_setdetachstate(&detached_thread, PTHREAD_CREATE_DETACHED);
+
+ for (i = 0; i < num_threads; i++) {
+ pthread_t thread_id;
+ while (pthread_create(&thread_id, &detached_thread, thread, 0) == EAGAIN) {
+ /* let some threads die, so system can breathe. :) */
+ sleep(1);
+ }
+ }
+
+ pthread_exit(0);
+}
diff --git a/linuxthreads/Makefile b/linuxthreads/Makefile
index b57abd1..cf01102 100644
--- a/linuxthreads/Makefile
+++ b/linuxthreads/Makefile
@@ -60,7 +60,7 @@ endif
librt-tests = ex10 ex11
tests = ex1 ex2 ex3 ex4 ex5 ex6 ex7 ex8 ex9 $(librt-tests) ex12 ex13 joinrace \
tststack $(tests-nodelete-$(have-z-nodelete)) ecmutex ex14 ex15 ex16 \
- ex17 tst-cancel tst-context
+ ex17 ex18 tst-cancel tst-context
ifeq (yes,$(build-shared))
tests-nodelete-yes = unload
diff --git a/linuxthreads/internals.h b/linuxthreads/internals.h
index ae49266..8297c78 100644
--- a/linuxthreads/internals.h
+++ b/linuxthreads/internals.h
@@ -208,7 +208,7 @@ struct pthread_request {
pthread_descr req_thread; /* Thread doing the request */
enum { /* Request kind */
REQ_CREATE, REQ_FREE, REQ_PROCESS_EXIT, REQ_MAIN_THREAD_EXIT,
- REQ_POST, REQ_DEBUG, REQ_KICK
+ REQ_POST, REQ_DEBUG, REQ_KICK, REQ_FOR_EACH_THREAD
} req_kind;
union { /* Arguments for request */
struct { /* For REQ_CREATE: */
@@ -224,6 +224,10 @@ struct pthread_request {
int code; /* exit status */
} exit;
void * post; /* For REQ_POST: the semaphore */
+ struct { /* For REQ_FOR_EACH_THREAD: callback */
+ void (*fn)(void *, pthread_descr);
+ void *arg;
+ } for_each;
} req_args;
};
diff --git a/linuxthreads/manager.c b/linuxthreads/manager.c
index 0872146..b1a4542 100644
--- a/linuxthreads/manager.c
+++ b/linuxthreads/manager.c
@@ -100,6 +100,8 @@ static void pthread_handle_exit(pthread_descr issuing_thread, int exitcode)
__attribute__ ((noreturn));
static void pthread_reap_children(void);
static void pthread_kill_all_threads(int sig, int main_thread_also);
+static void pthread_for_each_thread(void *arg,
+ void (*fn)(void *, pthread_descr));
/* The server thread managing requests for thread creation and termination */
@@ -211,6 +213,11 @@ __pthread_manager(void *arg)
/* This is just a prod to get the manager to reap some
threads right away, avoiding a potential delay at shutdown. */
break;
+ case REQ_FOR_EACH_THREAD:
+ pthread_for_each_thread(request.req_args.for_each.arg,
+ request.req_args.for_each.fn);
+ restart(request.req_thread);
+ break;
}
}
}
@@ -902,6 +909,20 @@ static void pthread_kill_all_threads(int sig, int main_thread_also)
}
}
+static void pthread_for_each_thread(void *arg,
+ void (*fn)(void *, pthread_descr))
+{
+ pthread_descr th;
+
+ for (th = __pthread_main_thread->p_nextlive;
+ th != __pthread_main_thread;
+ th = th->p_nextlive) {
+ fn(arg, th);
+ }
+
+ fn(arg, __pthread_main_thread);
+}
+
/* Process-wide exit() */
static void pthread_handle_exit(pthread_descr issuing_thread, int exitcode)
diff --git a/linuxthreads/specific.c b/linuxthreads/specific.c
index a7fa8ff..1a0cab1 100644
--- a/linuxthreads/specific.c
+++ b/linuxthreads/specific.c
@@ -20,6 +20,7 @@
#include "pthread.h"
#include "internals.h"
#include "spinlock.h"
+#include "restart.h"
#include <bits/libc-lock.h>
@@ -58,13 +59,38 @@ int __pthread_key_create(pthread_key_t * key, destr_function destr)
}
strong_alias (__pthread_key_create, pthread_key_create)
-/* Delete a key */
+/* Reset deleted key's value to NULL in each live thread.
+ * NOTE: this executes in the context of the thread manager! */
+
+struct pthread_key_delete_helper_args {
+ /* Damn, we need lexical closures in C! ;) */
+ unsigned int idx1st, idx2nd;
+ pthread_descr self;
+};
+
+static void pthread_key_delete_helper(void *arg, pthread_descr th)
+{
+ struct pthread_key_delete_helper_args *args = arg;
+ unsigned int idx1st = args->idx1st;
+ unsigned int idx2nd = args->idx2nd;
+ pthread_descr self = args->self;
+
+ if (self == 0)
+ self = args->self = thread_self();
+
+ if (!th->p_terminated) {
+ /* pthread_exit() may try to free th->p_specific[idx1st] concurrently. */
+ __pthread_lock(THREAD_GETMEM(th, p_lock), self);
+ if (th->p_specific[idx1st] != NULL)
+ th->p_specific[idx1st][idx2nd] = NULL;
+ __pthread_unlock(THREAD_GETMEM(th, p_lock));
+ }
+}
+/* Delete a key */
int pthread_key_delete(pthread_key_t key)
{
pthread_descr self = thread_self();
- pthread_descr th;
- unsigned int idx1st, idx2nd;
pthread_mutex_lock(&pthread_keys_mutex);
if (key >= PTHREAD_KEYS_MAX || !pthread_keys[key].in_use) {
@@ -73,23 +99,29 @@ int pthread_key_delete(pthread_key_t key)
}
pthread_keys[key].in_use = 0;
pthread_keys[key].destr = NULL;
+
/* Set the value of the key to NULL in all running threads, so
that if the key is reallocated later by pthread_key_create, its
associated values will be NULL in all threads. */
- idx1st = key / PTHREAD_KEY_2NDLEVEL_SIZE;
- idx2nd = key % PTHREAD_KEY_2NDLEVEL_SIZE;
- th = self;
- do {
- /* If the thread already is terminated don't modify the memory. */
- if (!th->p_terminated) {
- /* pthread_exit() may try to free th->p_specific[idx1st] concurrently. */
- __pthread_lock(THREAD_GETMEM(th, p_lock), self);
- if (th->p_specific[idx1st] != NULL)
- th->p_specific[idx1st][idx2nd] = NULL;
- __pthread_unlock(THREAD_GETMEM(th, p_lock));
- }
- th = th->p_nextlive;
- } while (th != self);
+
+ {
+ struct pthread_key_delete_helper_args args;
+ struct pthread_request request;
+
+ args.idx1st = key / PTHREAD_KEY_2NDLEVEL_SIZE;
+ args.idx2nd = key % PTHREAD_KEY_2NDLEVEL_SIZE;
+ args.self = 0;
+
+ request.req_thread = self;
+ request.req_kind = REQ_FOR_EACH_THREAD;
+ request.req_args.for_each.arg = &args;
+ request.req_args.for_each.fn = pthread_key_delete_helper;
+
+ TEMP_FAILURE_RETRY(__libc_write(__pthread_manager_request,
+ (char *) &request, sizeof(request)));
+ suspend(self);
+ }
+
pthread_mutex_unlock(&pthread_keys_mutex);
return 0;
}
generated by cgit v1.1 at 2024-11-23 17:44:19 +0000