[PATCH] kexec code cleanup

[linux-2.6] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index a28d11e10877d07ebdd1ccde6006493122873b28..2c7806873bfd1b656b5dc033a6abaf4ff535531f 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1003,9 +1003,6 @@ static task_t *copy_process(unsigned long clone_flags,
        p->pdeath_signal = 0;
        p->exit_state = 0;
 
-       /* Perform scheduler related setup */
-       sched_fork(p);
-
        /*
         * Ok, make it visible to the rest of the system.
         * We dont wake it up yet.
@@ -1014,18 +1011,24 @@ static task_t *copy_process(unsigned long clone_flags,
        INIT_LIST_HEAD(&p->ptrace_children);
        INIT_LIST_HEAD(&p->ptrace_list);
 
+       /* Perform scheduler related setup. Assign this task to a CPU. */
+       sched_fork(p, clone_flags);
+
        /* Need tasklist lock for parent etc handling! */
        write_lock_irq(&tasklist_lock);
 
        /*
-        * The task hasn't been attached yet, so cpus_allowed mask cannot
-        * have changed. The cpus_allowed mask of the parent may have
-        * changed after it was copied first time, and it may then move to
-        * another CPU - so we re-copy it here and set the child's CPU to
-        * the parent's CPU. This avoids alot of nasty races.
+        * The task hasn't been attached yet, so its cpus_allowed mask will
+        * not be changed, nor will its assigned CPU.
+        *
+        * The cpus_allowed mask of the parent may have changed after it was
+        * copied first time - so re-copy it here, then check the child's CPU
+        * to ensure it is on a valid CPU (and if not, just force it back to
+        * parent's CPU). This avoids alot of nasty races.
         */
        p->cpus_allowed = current->cpus_allowed;
-       set_task_cpu(p, smp_processor_id());
+       if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed)))
+               set_task_cpu(p, smp_processor_id());
 
        /*
         * Check for pending SIGKILL! The new thread should not be allowed