mmiotrace: print header using the read hook.

Now the header is printed only for `trace_pipe' file.

Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index 79be4a18ec1e9837a6dc6a7b623b28c0a539862a..6d2edbdde93943d66faf6919255659f68b015371 100644 (file)
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -12,6 +12,10 @@
 
 #include "trace.h"
 
+struct header_iter {
+       struct pci_dev *dev;
+};
+
 static struct trace_array *mmio_trace_array;
 
 static void mmio_reset_data(struct trace_array *tr)
@@ -89,17 +93,57 @@ static int mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
        return ret;
 }
 
-/* XXX: This is not called for trace_pipe file! */
-static void mmio_print_header(struct trace_iterator *iter)
+static void destroy_header_iter(struct header_iter *hiter)
+{
+       if (!hiter)
+               return;
+       pci_dev_put(hiter->dev);
+       kfree(hiter);
+}
+
+static void mmio_pipe_open(struct trace_iterator *iter)
 {
+       struct header_iter *hiter;
        struct trace_seq *s = &iter->seq;
-       struct pci_dev *dev = NULL;
 
        trace_seq_printf(s, "VERSION 20070824\n");
 
-       for_each_pci_dev(dev)
-               mmio_print_pcidev(s, dev);
-       /* XXX: return value? What if header is very long? */
+       hiter = kzalloc(sizeof(*hiter), GFP_KERNEL);
+       if (!hiter)
+               return;
+
+       hiter->dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, NULL);
+       iter->private = hiter;
+}
+
+/* XXX: This is not called when the pipe is closed! */
+static void mmio_close(struct trace_iterator *iter)
+{
+       struct header_iter *hiter = iter->private;
+       destroy_header_iter(hiter);
+       iter->private = NULL;
+}
+
+static ssize_t mmio_read(struct trace_iterator *iter, struct file *filp,
+                               char __user *ubuf, size_t cnt, loff_t *ppos)
+{
+       ssize_t ret;
+       struct header_iter *hiter = iter->private;
+       struct trace_seq *s = &iter->seq;
+
+       if (!hiter)
+               return 0;
+
+       mmio_print_pcidev(s, hiter->dev);
+       hiter->dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, hiter->dev);
+
+       if (!hiter->dev) {
+               destroy_header_iter(hiter);
+               iter->private = NULL;
+       }
+
+       ret = trace_seq_to_user(s, ubuf, cnt);
+       return (ret == -EBUSY) ? 0 : ret;
 }
 
 static int mmio_print_rw(struct trace_iterator *iter)
@@ -190,7 +234,9 @@ static struct tracer mmio_tracer __read_mostly =
        .name           = "mmiotrace",
        .init           = mmio_trace_init,
        .reset          = mmio_trace_reset,
-       .open           = mmio_print_header,
+       .pipe_open      = mmio_pipe_open,
+       .close          = mmio_close,
+       .read           = mmio_read,
        .ctrl_update    = mmio_trace_ctrl_update,
        .print_line     = mmio_print_line,
 };