Module: xenomai-forge
Branch: master
Commit: 0b0888a2022a3acd215992b03262c32ca6ad7c36
URL:
http://git.xenomai.org/?p=xenomai-forge.git;a=commit;h=0b0888a2022a3acd215992b03262c32ca6ad7c36
Author: Philippe Gerum <r...@xenomai.org>
Date: Thu Jan 9 10:47:22 2014 +0100
copperplate/threadobj: fix suspend vs deletion race (mercury)
Over Mercury, the notifier wait action should not be entered if a
cancellation request is pending. Otherwise, the thread pending
deletion would sleep in notifier_wait(), with the requestor waiting in
cancel_sync(), both indefinitely.
---
include/copperplate/threadobj.h | 1 +
lib/copperplate/threadobj.c | 19 ++++++++++---------
2 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/include/copperplate/threadobj.h b/include/copperplate/threadobj.h
index 184c711..218c274 100644
--- a/include/copperplate/threadobj.h
+++ b/include/copperplate/threadobj.h
@@ -124,6 +124,7 @@ void threadobj_save_timeout(struct threadobj_corespec
*corespec,
#define __THREAD_S_ACTIVE (1 << 5) /* Running user code. */
#define __THREAD_S_SUSPENDED (1 << 6) /* Suspended via
threadobj_suspend(). */
#define __THREAD_S_SAFE (1 << 7) /* TCB release
deferred. */
+#define __THREAD_S_ZOMBIE (1 << 8) /* Deletion process ongoing. */
#define __THREAD_S_DEBUG (1 << 31) /* Debug mode enabled. */
/*
* threadobj->run_state, locklessly updated by "current", merged
diff --git a/lib/copperplate/threadobj.c b/lib/copperplate/threadobj.c
index a31479c..c54cdf8 100644
--- a/lib/copperplate/threadobj.c
+++ b/lib/copperplate/threadobj.c
@@ -420,11 +420,13 @@ static void notifier_callback(const struct notifier *nf)
* threadobj_suspend().
*/
threadobj_lock(current);
- current->status |= __THREAD_S_SUSPENDED;
- threadobj_unlock(current);
- notifier_wait(nf); /* Wait for threadobj_resume(). */
- threadobj_lock(current);
- current->status &= ~__THREAD_S_SUSPENDED;
+ if ((current->status & __THREAD_S_ZOMBIE) == 0) {
+ current->status |= __THREAD_S_SUSPENDED;
+ threadobj_unlock(current);
+ notifier_wait(nf); /* Wait for threadobj_resume(). */
+ threadobj_lock(current);
+ current->status &= ~__THREAD_S_SUSPENDED;
+ }
threadobj_unlock(current);
}
@@ -488,7 +490,7 @@ static inline void threadobj_run_corespec(struct threadobj
*thobj)
{
}
-static inline void threadobj_cancel_corespec(struct threadobj *thobj)
+static inline void threadobj_cancel_corespec(struct threadobj *thobj) /*
thobj->lock held */
{
}
@@ -872,9 +874,9 @@ void threadobj_init(struct threadobj *thobj,
static void destroy_thread(struct threadobj *thobj)
{
+ threadobj_cleanup_corespec(thobj);
__RT(pthread_cond_destroy(&thobj->barrier));
__RT(pthread_mutex_destroy(&thobj->lock));
- threadobj_cleanup_corespec(thobj);
}
void threadobj_destroy(struct threadobj *thobj) /* thobj->lock free */
@@ -1089,8 +1091,6 @@ static void cancel_sync(struct threadobj *thobj) /*
thobj->lock held */
int oldstate, ret = 0;
sem_t *sem;
- __threadobj_check_locked(thobj);
-
/*
* We have to allocate the cancel sync sema4 in the main heap
* dynamically, so that it always live in valid memory when we
@@ -1106,6 +1106,7 @@ static void cancel_sync(struct threadobj *thobj) /*
thobj->lock held */
__STD(sem_init(sem, sem_scope_attribute, 0));
thobj->cancel_sem = sem;
+ thobj->status |= __THREAD_S_ZOMBIE;
/*
* If the thread to delete is warming up, wait until it
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