[Xenomai-git] Philippe Gerum : copperplate/syncobj: prevent concurrent locking while a deletion is pending

[GIT version control]

Module: xenomai-forge
Branch: master
Commit: a739260b1d94c0dd15df5f80ddd63d122f2c74ed
URL:    
http://git.xenomai.org/?p=xenomai-forge.git;a=commit;h=a739260b1d94c0dd15df5f80ddd63d122f2c74ed

Author: Philippe Gerum <r...@xenomai.org>
Date:   Wed Dec 14 19:00:44 2011 +0100

copperplate/syncobj: prevent concurrent locking while a deletion is pending

---

 include/copperplate/syncobj.h |    3 +++
 lib/copperplate/syncobj.c     |    9 +++++++++
 2 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/include/copperplate/syncobj.h b/include/copperplate/syncobj.h
index 5112c02..e3f0b01 100644
--- a/include/copperplate/syncobj.h
+++ b/include/copperplate/syncobj.h
@@ -41,6 +41,8 @@
 #define SYNCOBJ_BLOCK  0x1
 #define SYNCOBJ_RESUME 0x2
 
+#define SYNCOBJ_MAGIC  0xf9f99f9f
+
 struct threadobj;
 
 struct syncstate {
@@ -63,6 +65,7 @@ struct syncobj_corespec {
 #endif /* CONFIG_XENO_MERCURY */
 
 struct syncobj {
+       unsigned int magic;
        int flags;
        int release_count;
        struct list pend_list;
diff --git a/lib/copperplate/syncobj.c b/lib/copperplate/syncobj.c
index a70a7d2..c3323ea 100644
--- a/lib/copperplate/syncobj.c
+++ b/lib/copperplate/syncobj.c
@@ -223,6 +223,7 @@ void syncobj_init(struct syncobj *sobj, int flags,
        sobj->drain_count = 0;
        sobj->release_count = 0;
        sobj->finalizer = finalizer;
+       sobj->magic = SYNCOBJ_MAGIC;
        syncobj_init_corespec(sobj);
 }
 
@@ -232,6 +233,13 @@ int syncobj_lock(struct syncobj *sobj, struct syncstate 
*syns)
 
        assert(threadobj_current() != NULL);
 
+       /*
+        * This magic prevents concurrent locking while a deletion is
+        * in progress, waiting for the release count to drop to zero.
+        */
+       if (sobj->magic != SYNCOBJ_MAGIC)
+               return -EINVAL;
+
        pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
 
        ret = monitor_enter(sobj);
@@ -561,6 +569,7 @@ int syncobj_destroy(struct syncobj *sobj, struct syncstate 
*syns)
 
        __syncobj_check_locked(sobj);
 
+       sobj->magic = ~SYNCOBJ_MAGIC;
        ret = syncobj_flush(sobj, SYNCOBJ_DELETED);
        if (ret == 0) {
                /* No thread awaken - we may dispose immediately. */


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