Re: [Xenomai-core] [PATCH] fix pthread cancellation in native skin

[Philippe Gerum]

Philippe Gerum wrote:
Gilles Chanteperdrix wrote:
Gilles Chanteperdrix wrote:
 > This is not the only situation where a thread with a nucleus 
suspension
 > bit need to run shortly in secondary mode: it also occurs when
 > suspending with xnpod_suspend_thread() a thread running in secondary
 > mode; the thread receives the SIGCHLD signal and need to execute 
shortly
 > with the suspension bit set in order to cause a migration to primary
 > mode.
 >  > So, the only case when we are sure that a user-space thread can 
not be
 > scheduled by Linux seems to be when this thread does not have the
 > XNRELAX bit.

From all the bits in XNTHREAD_BLOCK_BITS, only when the XNPEND bit is
set, a thread can not be running in secondary mode. Hence the proposed
patch.


Almost ok, but XNDELAY might also be set alone, indicating a purely 
timed wait state (i.e. without sync object to pend on, so XNPEND is off).


Forget about this: XNDELAY might also be a transient bit like XNSUSP, so you are 
right, we cannot test it there.



------------------------------------------------------------------------

Index: ksrc/nucleus/shadow.c
===================================================================
--- ksrc/nucleus/shadow.c    (revision 507)
+++ ksrc/nucleus/shadow.c    (working copy)
@@ -1543,14 +1543,25 @@
 
 #ifdef CONFIG_XENO_OPT_DEBUG
     {
-    xnflags_t status = threadin->status & ~XNRELAX;
+    xnflags_t status = threadin->status;
     int sigpending = signal_pending(next);
 
-        if (!(next->ptrace & PT_PTRACED) &&
+        if (!testbits(status, XNRELAX))
+            {
+            show_stack(xnthread_user_task(threadin),NULL);
+            xnpod_fatal("Hardened thread %s[%d] running in Linux 
domain?! (status=0x%lx, sig=%d, prev=%s[%d])",
+            threadin->name,
+            next->pid,
+            status,
+            sigpending,
+            prev->comm,
+            prev->pid);
+        }
+        else if (!(next->ptrace & PT_PTRACED) &&
         /* Allow ptraced threads to run shortly in order to
            properly recover from a stopped state. */
         testbits(status,XNSTARTED) &&
-        testbits(status,XNTHREAD_BLOCK_BITS))
+        testbits(status,XNPEND))
         {
         show_stack(xnthread_user_task(threadin),NULL);
             xnpod_fatal("blocked thread %s[%d] rescheduled?! 
(status=0x%lx, sig=%d, prev=%s[%d])",


------------------------------------------------------------------------

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--

Philippe.

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