Re: [Xenomai-core] [RFC][PATCH 1/2] rework shadow CPU affinity

[Jan Kiszka <jan.kiszka@domain.hid>]

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Second try of this patch, now consequently basing the affinity API for
xnshadow_map on current->cpus_allowed (affects the native skin). Just
like the current code does, this patch restricts a shadow thread to a
single (the first) CPU of its affinity mask.

Jan

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---
 ksrc/nucleus/shadow.c       |   35 +++++++++++++----------------------
 ksrc/skins/native/syscall.c |    3 +++
 2 files changed, 16 insertions(+), 22 deletions(-)

Index: xenomai/ksrc/nucleus/shadow.c
===================================================================
--- xenomai.orig/ksrc/nucleus/shadow.c
+++ xenomai/ksrc/nucleus/shadow.c
@@ -409,18 +409,6 @@ static void lostage_handler(void *cookie
 		xnltt_log_event(xeno_ev_lohandler, reqnum, p->comm, p->pid);
 
 		switch (rq->req[reqnum].type) {
-		case LO_START_REQ:
-
-#ifdef CONFIG_SMP
-			if (xnshadow_thread(p))
-				/* Set up the initial task affinity using the
-				   information passed to xnpod_start_thread(). */
-				set_cpus_allowed(p,
-						 xnshadow_thread(p)->affinity);
-#endif /* CONFIG_SMP */
-
-			goto do_wakeup;
-
 		case LO_WAKEUP_REQ:
 
 #ifdef CONFIG_SMP
@@ -443,7 +431,9 @@ static void lostage_handler(void *cookie
 			if (!xnshadow_thread(current))
 				xnpod_renice_root(XNPOD_ROOT_PRIO_BASE);
 #endif /* CONFIG_XENO_OPT_RPIDISABLE */
-		      do_wakeup:
+
+			/* fall through */
+		case LO_START_REQ:
 
 #ifdef CONFIG_XENO_OPT_ISHIELD
 			if (xnshadow_thread(p) &&
@@ -853,22 +843,23 @@ int xnshadow_map(xnthread_t *thread, xnc
 	xnshadow_thrptd(current) = thread;
 	xnpod_suspend_thread(thread, XNRELAX, XN_INFINITE, NULL);
 
+	/* Restrict affinity to a single CPU of the current set */
+	affinity = xnarch_cpumask_of_cpu(
+		xnarch_first_cpu(current->cpus_allowed));
+	set_cpus_allowed(current, affinity);
+
 	if (u_completion) {
 		xnshadow_signal_completion(u_completion, 0);
 		return 0;
 	}
 
-	/* Nobody waits for us, so we may start the shadow immediately
-	   after having forced the CPU affinity to the current
-	   processor. Note that we don't use smp_processor_id() to prevent
-	   kernel debug stuff to yell at us for calling it in a preemptible
-	   section of code. */
-
-	affinity = xnarch_cpumask_of_cpu(rthal_processor_id());
-	set_cpus_allowed(current, affinity);
+	/* Nobody waits for us, so we may start the shadow immediately. */
 
 	mode = thread->rrperiod != XN_INFINITE ? XNRRB : 0;
-	xnpod_start_thread(thread, mode, 0, affinity, NULL, NULL);
+	err = xnpod_start_thread(thread, mode, 0, affinity, NULL, NULL);
+
+	if (err)
+		return err;
 
 	err = xnshadow_harden();
 
Index: xenomai/ksrc/skins/native/syscall.c
===================================================================
--- xenomai.orig/ksrc/skins/native/syscall.c
+++ xenomai/ksrc/skins/native/syscall.c
@@ -168,6 +168,9 @@ static int __rt_task_create(struct task_
 	err = rt_task_create(task, name, 0, prio, XNFPU | XNSHADOW | mode);
 
 	if (err == 0) {
+		/* Apply CPU affinity */
+		set_cpus_allowed(current, task->affinity);
+
 		/* Copy back the registry handle to the ph struct. */
 		ph.opaque = xnthread_handle(&task->thread_base);
 		ph.opaque2 = bulk.a5;	/* hidden pthread_t identifier. */

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