[MTD] mtdoops: Add a magic number to logged kernel oops

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=f0482ee3669a78bdb1e15b9f9c58a9f1ffc5a997
Commit:     f0482ee3669a78bdb1e15b9f9c58a9f1ffc5a997
Parent:     ecd5b3102322011610a2521c389ab5804c811837
Author:     Richard Purdie <rpurdie at rpsys.net>
AuthorDate: Sat Jul 26 09:22:45 2008 +0100
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Sat Oct 18 11:51:27 2008 +0100

    [MTD] mtdoops: Add a magic number to logged kernel oops
    
    Add a magic number to logged kernel oops messages so that they
    can be more accurately detected rather than just having to rely
    on the sequence number. This also allows easier detection of
    saved crashes by userspace.
    
    Signed-off-by: Richard Purdie <rpurdie at rpsys.net>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/mtdoops.c |   32 ++++++++++++++++++--------------
 1 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index f40e457..6f6b2f3 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -33,6 +33,7 @@
 #include <linux/interrupt.h>
 #include <linux/mtd/mtd.h>
 
+#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00
 #define OOPS_PAGE_SIZE 4096
 
 static struct mtdoops_context {
@@ -224,31 +225,33 @@ static void find_next_position(struct mtdoops_context *cxt)
 {
 	struct mtd_info *mtd = cxt->mtd;
 	int ret, page, maxpos = 0;
-	u32 count, maxcount = 0xffffffff;
+	u32 count[2], maxcount = 0xffffffff;
 	size_t retlen;
 
 	for (page = 0; page < cxt->oops_pages; page++) {
-		ret = mtd->read(mtd, page * OOPS_PAGE_SIZE, 4, &retlen, (u_char *) &count);
-		if ((retlen != 4) || ((ret < 0) && (ret != -EUCLEAN))) {
-			printk(KERN_ERR "mtdoops: Read failure at %d (%td of 4 read)"
+		ret = mtd->read(mtd, page * OOPS_PAGE_SIZE, 8, &retlen, (u_char *) &count[0]);
+		if ((retlen != 8) || ((ret < 0) && (ret != -EUCLEAN))) {
+			printk(KERN_ERR "mtdoops: Read failure at %d (%td of 8 read)"
 				", err %d.\n", page * OOPS_PAGE_SIZE, retlen, ret);
 			continue;
 		}
 
-		if (count == 0xffffffff)
+		if (count[1] != MTDOOPS_KERNMSG_MAGIC)
+			continue;
+		if (count[0] == 0xffffffff)
 			continue;
 		if (maxcount == 0xffffffff) {
-			maxcount = count;
+			maxcount = count[0];
 			maxpos = page;
-		} else if ((count < 0x40000000) && (maxcount > 0xc0000000)) {
-			maxcount = count;
+		} else if ((count[0] < 0x40000000) && (maxcount > 0xc0000000)) {
+			maxcount = count[0];
 			maxpos = page;
-		} else if ((count > maxcount) && (count < 0xc0000000)) {
-			maxcount = count;
+		} else if ((count[0] > maxcount) && (count[0] < 0xc0000000)) {
+			maxcount = count[0];
 			maxpos = page;
-		} else if ((count > maxcount) && (count > 0xc0000000)
+		} else if ((count[0] > maxcount) && (count[0] > 0xc0000000)
 					&& (maxcount > 0x80000000)) {
-			maxcount = count;
+			maxcount = count[0];
 			maxpos = page;
 		}
 	}
@@ -358,8 +361,9 @@ mtdoops_console_write(struct console *co, const char *s, unsigned int count)
 
 	if (cxt->writecount == 0) {
 		u32 *stamp = cxt->oops_buf;
-		*stamp = cxt->nextcount;
-		cxt->writecount = 4;
+		*stamp++ = cxt->nextcount;
+		*stamp = MTDOOPS_KERNMSG_MAGIC;
+		cxt->writecount = 8;
 	}
 
 	if ((count + cxt->writecount) > OOPS_PAGE_SIZE)