[Xenomai-git] Philippe Gerum : posix, vrtx: catch unexpected sync errors with thread trampoline

[git repository hosting]

Module: xenomai-2.6
Branch: master
Commit: 435f87958222c885b3dd94c9c7b2ef9c01efda7b
URL:    
http://git.xenomai.org/?p=xenomai-2.6.git;a=commit;h=435f87958222c885b3dd94c9c7b2ef9c01efda7b

Author: Philippe Gerum <r...@xenomai.org>
Date:   Mon Dec  9 12:11:20 2013 +0100

posix, vrtx: catch unexpected sync errors with thread trampoline

If __real_sem_wait() fails synchronizing with the trampoline, we
simply can't continue, as this usually reveals a general issue with
regular IPCs on the platform.

This also plugs a nasty bug causing the POSIX thread trampoline to
execute random start code, as the argument structure living on its
parent thread's stack could be trashed, once the latter has returned
to the caller because of a synchronization failure.

---

 src/skins/posix/thread.c |   28 +++++++++++++++++++---------
 src/skins/vrtx/task.c    |   12 +++++++++++-
 2 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/src/skins/posix/thread.c b/src/skins/posix/thread.c
index 31055f8..b63e197 100644
--- a/src/skins/posix/thread.c
+++ b/src/skins/posix/thread.c
@@ -20,6 +20,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
+#include <error.h>
 #include <signal.h>
 #include <unistd.h>
 #include <pthread.h>
@@ -264,17 +265,26 @@ int __wrap_pthread_create(pthread_t *tid,
        __real_sem_init(&iargs.sync, 0, 0);
 
        err = __real_pthread_create(&ltid, attr,
-                                   &__pthread_trampoline, &iargs);
-
-       if (!err)
-               while (__real_sem_wait(&iargs.sync) && errno == EINTR) ;
+                                   __pthread_trampoline, &iargs);
+       if (err)
+               goto out;
+
+       for (;;) {
+               err = __real_sem_wait(&iargs.sync);
+               if (err && errno == EINTR)
+                       continue;
+               if (err == 0) {
+                       err = iargs.ret;
+                       if (err == 0)
+                               *tid = ltid;
+                       break;
+               }
+               /* We can't continue if we can't sync up. */
+               error(1, errno, "__real_sem_wait");
+       }
+out:
        __real_sem_destroy(&iargs.sync);
 
-       err = err ?: iargs.ret;
-
-       if (!err)
-               *tid = ltid;
-
        return err;
 }
 
diff --git a/src/skins/vrtx/task.c b/src/skins/vrtx/task.c
index 310dedf..400a9f7 100644
--- a/src/skins/vrtx/task.c
+++ b/src/skins/vrtx/task.c
@@ -22,6 +22,7 @@
 #include <malloc.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <error.h>
 #include <pthread.h>
 #include <semaphore.h>
 #include <signal.h>
@@ -169,7 +170,16 @@ int sc_tecreate(void (*entry) (void *),
                return -1;
        }
 
-       while (__real_sem_wait(&iargs.sync) && errno == EINTR) ;
+       for (;;) {
+               err = __real_sem_wait(&iargs.sync);
+               if (err && errno == EINTR)
+                       continue;
+               if (err == 0)
+                       break;
+               /* We can't continue if we can't sync up. */
+               error(1, errno, "__real_sem_wait");
+       }
+
        __real_sem_destroy(&iargs.sync);
 
        return iargs.tid;


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