[Xenomai-core] [PATCH v2 4/4] POSIX: Do not auto-shadow main with dlopen enabled

[Jan Kiszka]

Don't perform auto-shadowing in POSIX skin if we might be loaded via
dlopen. Otherwise the wrong thread, the undefined dlopen caller, may be
(re-)shadowed, assigning wrong scheduling settings.

Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
---

 src/skins/posix/init.c |   43 ++++++++++++++++++++++++++++---------------
 1 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/src/skins/posix/init.c b/src/skins/posix/init.c
index 8fc5a92..b04dbf0 100644
--- a/src/skins/posix/init.c
+++ b/src/skins/posix/init.c
@@ -47,7 +47,6 @@ void pse51_clock_init(int);
 static __attribute__ ((constructor))
 void __init_posix_interface(void)
 {
-       struct sched_param parm;
        int muxid, err;
 
        muxid =
@@ -67,28 +66,42 @@ void __init_posix_interface(void)
                                                                 
__rtdm_fdcount);
        }
 
-       /* Shadow the main thread. mlock the whole memory for the time of the
-          syscall, in order to avoid the SIGXCPU signal. */
+#ifdef CONFIG_XENO_LIBS_DLOPEN
+       /* Don't use auto-shadowing if we are likely invoked from dlopen, but
+          take care of auto-mlockall. */
+#ifdef CONFIG_XENO_POSIX_AUTO_MLOCKALL
        if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
                perror("Xenomai Posix skin init: mlockall");
                exit(EXIT_FAILURE);
        }
+#endif /* CONFIG_XENO_POSIX_AUTO_MLOCKALL */
+#else /* !CONFIG_XENO_LIBS_DLOPEN */
+       {
+               struct sched_param parm = { .sched_priority = 0 };
+
+               /* Shadow the main thread. mlock the whole memory for the time
+                  of the syscall, in order to avoid the SIGXCPU signal. */
+               if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
+                       perror("Xenomai Posix skin init: mlockall");
+                       exit(EXIT_FAILURE);
+               }
 
-       parm.sched_priority = 0;
-       err = __wrap_pthread_setschedparam(pthread_self(), SCHED_OTHER,
-                                          &parm);
-       if (err) {
-               fprintf(stderr, "Xenomai Posix skin init: "
-                       "pthread_setschedparam: %s\n", strerror(err));
-               exit(EXIT_FAILURE);
-       }
+               err = __wrap_pthread_setschedparam(pthread_self(), SCHED_OTHER,
+                                                  &parm);
+               if (err) {
+                       fprintf(stderr, "Xenomai Posix skin init: "
+                               "pthread_setschedparam: %s\n", strerror(err));
+                       exit(EXIT_FAILURE);
+               }
 
 #ifndef CONFIG_XENO_POSIX_AUTO_MLOCKALL
-       if (munlockall()) {
-               perror("Xenomai Posix skin init: munlockall");
-               exit(EXIT_FAILURE);
-       }
+               if (munlockall()) {
+                       perror("Xenomai Posix skin init: munlockall");
+                       exit(EXIT_FAILURE);
+               }
 #endif /* !CONFIG_XENO_POSIX_AUTO_MLOCKALL */
+       }
+#endif /* !CONFIG_XENO_LIBS_DLOPEN */
 
        if (!fork_handler_registered) {
                err = pthread_atfork(NULL, NULL, &__init_posix_interface);


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