- patches.suse/slab-handle-memoryless-nodes-v2a.patch: Refresh.

[linux-flexiantxendom0-3.2.10.git] / arch / arm / vfp / vfpmodule.c

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 2d7423a..f60a540 100644 (file)
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -38,16 +38,75 @@ union vfp_state *last_VFP_context[NR_CPUS];
  */
 unsigned int VFP_arch;
 
+/*
+ * Per-thread VFP initialization.
+ */
+static void vfp_thread_flush(struct thread_info *thread)
+{
+       union vfp_state *vfp = &thread->vfpstate;
+       unsigned int cpu;
+
+       memset(vfp, 0, sizeof(union vfp_state));
+
+       vfp->hard.fpexc = FPEXC_EN;
+       vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
+
+       /*
+        * Disable VFP to ensure we initialize it first.  We must ensure
+        * that the modification of last_VFP_context[] and hardware disable
+        * are done for the same CPU and without preemption.
+        */
+       cpu = get_cpu();
+       if (last_VFP_context[cpu] == vfp)
+               last_VFP_context[cpu] = NULL;
+       fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
+       put_cpu();
+}
+
+static void vfp_thread_exit(struct thread_info *thread)
+{
+       /* release case: Per-thread VFP cleanup. */
+       union vfp_state *vfp = &thread->vfpstate;
+       unsigned int cpu = get_cpu();
+
+       if (last_VFP_context[cpu] == vfp)
+               last_VFP_context[cpu] = NULL;
+       put_cpu();
+}
+
+/*
+ * When this function is called with the following 'cmd's, the following
+ * is true while this function is being run:
+ *  THREAD_NOFTIFY_SWTICH:
+ *   - the previously running thread will not be scheduled onto another CPU.
+ *   - the next thread to be run (v) will not be running on another CPU.
+ *   - thread->cpu is the local CPU number
+ *   - not preemptible as we're called in the middle of a thread switch
+ *  THREAD_NOTIFY_FLUSH:
+ *   - the thread (v) will be running on the local CPU, so
+ *     v === current_thread_info()
+ *   - thread->cpu is the local CPU number at the time it is accessed,
+ *     but may change at any time.
+ *   - we could be preempted if tree preempt rcu is enabled, so
+ *     it is unsafe to use thread->cpu.
+ *  THREAD_NOTIFY_EXIT
+ *   - the thread (v) will be running on the local CPU, so
+ *     v === current_thread_info()
+ *   - thread->cpu is the local CPU number at the time it is accessed,
+ *     but may change at any time.
+ *   - we could be preempted if tree preempt rcu is enabled, so
+ *     it is unsafe to use thread->cpu.
+ */
 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
 {
        struct thread_info *thread = v;
-       union vfp_state *vfp;
-       __u32 cpu = thread->cpu;
 
        if (likely(cmd == THREAD_NOTIFY_SWITCH)) {
                u32 fpexc = fmrx(FPEXC);
 
 #ifdef CONFIG_SMP
+               unsigned int cpu = thread->cpu;
+
                /*
                 * On SMP, if VFP is enabled, save the old state in
                 * case the thread migrates to a different CPU. The
@@ -74,25 +133,10 @@ static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
                return NOTIFY_DONE;
        }
 
-       vfp = &thread->vfpstate;
-       if (cmd == THREAD_NOTIFY_FLUSH) {
-               /*
-                * Per-thread VFP initialisation.
-                */
-               memset(vfp, 0, sizeof(union vfp_state));
-
-               vfp->hard.fpexc = FPEXC_EN;
-               vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
-
-               /*
-                * Disable VFP to ensure we initialise it first.
-                */
-               fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
-       }
-
-       /* flush and release case: Per-thread VFP cleanup. */
-       if (last_VFP_context[cpu] == vfp)
-               last_VFP_context[cpu] = NULL;
+       if (cmd == THREAD_NOTIFY_FLUSH)
+               vfp_thread_flush(thread);
+       else
+               vfp_thread_exit(thread);
 
        return NOTIFY_DONE;
 }