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Subject[PATCH 2/5] mmiotrace: print header using the read hook.
From edf8d48e6bea0202536f3221bc4098f88278645f Mon Sep 17 00:00:00 2001
From: Pekka Paalanen <pq@iki.fi>
Date: Sat, 26 Apr 2008 23:05:23 +0300
Subject: [PATCH] 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>
---
kernel/trace/trace_mmiotrace.c | 60 +++++++++++++++++++++++++++++++++++----
1 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index 79be4a1..6d2edbd 100644
--- 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,
};
--
1.5.3.7


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