Changes in kernel/generic/src/proc/thread.c [c7326f21:b169619] in mainline

File:

• kernel/generic/src/proc/thread.c (modified) (6 diffs)

kernel/generic/src/proc/thread.c

@@ -62 +62 @@
 #include <arch/faddr.h>
 #include <atomic.h>
-#include <mem.h>
+#include <memw.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -231 +231 @@
         irq_spinlock_lock(&thread->lock, true);
         thread->cpu = cpu;
-        thread->wired = true;
+        thread->nomigrate++;
         irq_spinlock_unlock(&thread->lock, true);
 }
@@ -259 +259 @@
             ++thread->priority : thread->priority;
 
-        cpu_t *cpu;
-        if (thread->wired || thread->nomigrate || thread->fpu_context_engaged) {
-                /* Cannot ready to another CPU */
-                assert(thread->cpu != NULL);
-                cpu = thread->cpu;
-        } else if (thread->stolen) {
-                /* Ready to the stealing CPU */
-                cpu = CPU;
-        } else if (thread->cpu) {
-                /* Prefer the CPU on which the thread ran last */
-                assert(thread->cpu != NULL);
-                cpu = thread->cpu;
-        } else {
-                cpu = CPU;
-        }
+        /* Prefer the CPU on which the thread ran last */
+        cpu_t *cpu = thread->cpu ? thread->cpu : CPU;
 
         thread->state = Ready;
@@ -348 +335 @@
         thread->priority = -1;          /* Start in rq[0] */
         thread->cpu = NULL;
-        thread->wired = false;
         thread->stolen = false;
         thread->uspace =
@@ -369 +355 @@
 
         thread->fpu_context_exists = false;
-        thread->fpu_context_engaged = false;
 
         odlink_initialize(&thread->lthreads);
@@ -426 +411 @@
 
         assert((thread->state == Exiting) || (thread->state == Lingering));
-        assert(thread->cpu);
 
         /* Clear cpu->fpu_owner if set to this thread. */
-        irq_spinlock_lock(&thread->cpu->lock, false);
-        if (thread->cpu->fpu_owner == thread)
-                thread->cpu->fpu_owner = NULL;
-        irq_spinlock_unlock(&thread->cpu->lock, false);
+#ifdef CONFIG_FPU_LAZY
+        if (thread->cpu) {
+                /*
+                 * We need to lock for this because the old CPU can concurrently try
+                 * to dump this thread's FPU state, in which case we need to wait for
+                 * it to finish. An atomic compare-and-swap wouldn't be enough.
+                 */
+                irq_spinlock_lock(&thread->cpu->fpu_lock, false);
+
+                thread_t *owner = atomic_load_explicit(&thread->cpu->fpu_owner,
+                    memory_order_relaxed);
+
+                if (owner == thread) {
+                        atomic_store_explicit(&thread->cpu->fpu_owner, NULL,
+                            memory_order_relaxed);
+                }
+
+                irq_spinlock_unlock(&thread->cpu->fpu_lock, false);
+        }
+#endif
 
         interrupts_restore(ipl);