Since page structs, which are used for linking PRAM nodes, are cleared
on boot, organize all PRAM nodes into a list singly-linked by pfn's
before reboot to facilitate the node list restore in the new kernel.
---
mm/pram.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/mm/pram.c b/mm/pram.c
index f7eebe1..c7706dc 100644
--- a/mm/pram.c
+++ b/mm/pram.c
@@ -1,11 +1,15 @@
#include <linux/err.h>
#include <linux/gfp.h>
#include <linux/highmem.h>
+#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
+#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/notifier.h>
#include <linux/pram.h>
+#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/types.h>
@@ -42,6 +46,9 @@ struct pram_link {
* singly-linked list of PRAM link structures (see above), the node has a
* pointer to the head of.
*
+ * To facilitate data restore in the new kernel, before reboot all PRAM nodes
+ * are organized into a list singly-linked by pfn's (see pram_reboot()).
+ *
* The structure occupies a memory page.
*/
struct pram_node {
@@ -49,6 +56,7 @@ struct pram_node {
__u32 type; /* data type, see enum pram_stream_type */
__u64 data_len; /* data size, only for byte streams */
__u64 link_pfn; /* points to the first link of the node */
+ __u64 node_pfn; /* points to the next node in the node list */
__u8 name[PRAM_NAME_MAX];
};
@@ -57,6 +65,10 @@ struct pram_node {
#define PRAM_LOAD 2
#define PRAM_ACCMODE_MASK 3
+/*
+ * For convenience sake PRAM nodes are kept in an auxiliary doubly-linked list
+ * connected through the lru field of the page struct.
+ */
static LIST_HEAD(pram_nodes); /* linked through page::lru */
static DEFINE_MUTEX(pram_mutex); /* serializes open/close */
@@ -521,3 +533,41 @@ size_t pram_read(struct pram_stream *ps, void *buf, size_t
count)
}
return read_count;
}
+
+/*
+ * Build the list of PRAM nodes.
+ */
+static void __pram_reboot(void)
+{
+ struct page *page;
+ struct pram_node *node;
+ unsigned long node_pfn = 0;
+
+ list_for_each_entry_reverse(page, &pram_nodes, lru) {
+ node = page_address(page);
+ if (WARN_ON(node->flags & PRAM_ACCMODE_MASK))
+ continue;
+ node->node_pfn = node_pfn;
+ node_pfn = page_to_pfn(page);
+ }
+}
+
+static int pram_reboot(struct notifier_block *notifier,
+ unsigned long val, void *v)
+{
+ if (val != SYS_RESTART)
+ return NOTIFY_DONE;
+ __pram_reboot();
+ return NOTIFY_OK;
+}
+
+static struct notifier_block pram_reboot_notifier = {
+ .notifier_call = pram_reboot,
+};
+
+static int __init pram_init(void)
+{
+ register_reboot_notifier(&pram_reboot_notifier);
+ return 0;
+}
+module_init(pram_init);
--
1.7.10.4
--
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