mtd: mtdoops: Create a header structure for the saved mtdoops.

Create a dump header to enable the addition of fields without having
to modify the rest of the code.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jean-Marc Eurin <jmeurin@google.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220421234244.2172003-3-jmeurin@google.com

diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 09a26747f4904e63c497d66a8930a9be1708c0ea..186eeb01bee11f62c871cc78d644ab95fdeaee41 100644 (file)
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -22,9 +22,6 @@
 /* Maximum MTD partition size */
 #define MTDOOPS_MAX_MTD_SIZE (8 * 1024 * 1024)
 
-#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00
-#define MTDOOPS_HEADER_SIZE   8
-
 static unsigned long record_size = 4096;
 module_param(record_size, ulong, 0400);
 MODULE_PARM_DESC(record_size,
@@ -40,6 +37,13 @@ module_param(dump_oops, int, 0600);
 MODULE_PARM_DESC(dump_oops,
                "set to 1 to dump oopses, 0 to only dump panics (default 1)");
 
+#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00
+
+struct mtdoops_hdr {
+       u32 seq;
+       u32 magic;
+} __packed;
+
 static struct mtdoops_context {
        struct kmsg_dumper dump;
 
@@ -178,16 +182,16 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
 {
        struct mtd_info *mtd = cxt->mtd;
        size_t retlen;
-       u32 *hdr;
+       struct mtdoops_hdr *hdr;
        int ret;
 
        if (test_and_set_bit(0, &cxt->oops_buf_busy))
                return;
 
        /* Add mtdoops header to the buffer */
-       hdr = cxt->oops_buf;
-       hdr[0] = cxt->nextcount;
-       hdr[1] = MTDOOPS_KERNMSG_MAGIC;
+       hdr = (struct mtdoops_hdr *)cxt->oops_buf;
+       hdr->seq = cxt->nextcount;
+       hdr->magic = MTDOOPS_KERNMSG_MAGIC;
 
        if (panic) {
                ret = mtd_panic_write(mtd, cxt->nextpage * record_size,
@@ -222,8 +226,9 @@ static void mtdoops_workfunc_write(struct work_struct *work)
 static void find_next_position(struct mtdoops_context *cxt)
 {
        struct mtd_info *mtd = cxt->mtd;
+       struct mtdoops_hdr hdr;
        int ret, page, maxpos = 0;
-       u32 count[MTDOOPS_HEADER_SIZE/sizeof(u32)], maxcount = 0xffffffff;
+       u32 maxcount = 0xffffffff;
        size_t retlen;
 
        for (page = 0; page < cxt->oops_pages; page++) {
@@ -231,32 +236,31 @@ static void find_next_position(struct mtdoops_context *cxt)
                        continue;
                /* Assume the page is used */
                mark_page_used(cxt, page);
-               ret = mtd_read(mtd, page * record_size, MTDOOPS_HEADER_SIZE,
-                              &retlen, (u_char *)&count[0]);
-               if (retlen != MTDOOPS_HEADER_SIZE ||
+               ret = mtd_read(mtd, page * record_size, sizeof(hdr),
+                              &retlen, (u_char *)&hdr);
+               if (retlen != sizeof(hdr) ||
                                (ret < 0 && !mtd_is_bitflip(ret))) {
-                       printk(KERN_ERR "mtdoops: read failure at %ld (%td of %d read), err %d\n",
-                              page * record_size, retlen,
-                              MTDOOPS_HEADER_SIZE, ret);
+                       printk(KERN_ERR "mtdoops: read failure at %ld (%zu of %zu read), err %d\n",
+                              page * record_size, retlen, sizeof(hdr), ret);
                        continue;
                }
 
-               if (count[0] == 0xffffffff && count[1] == 0xffffffff)
+               if (hdr.seq == 0xffffffff && hdr.magic == 0xffffffff)
                        mark_page_unused(cxt, page);
-               if (count[0] == 0xffffffff || count[1] != MTDOOPS_KERNMSG_MAGIC)
+               if (hdr.seq == 0xffffffff || hdr.magic != MTDOOPS_KERNMSG_MAGIC)
                        continue;
                if (maxcount == 0xffffffff) {
-                       maxcount = count[0];
+                       maxcount = hdr.seq;
                        maxpos = page;
-               } else if (count[0] < 0x40000000 && maxcount > 0xc0000000) {
-                       maxcount = count[0];
+               } else if (hdr.seq < 0x40000000 && maxcount > 0xc0000000) {
+                       maxcount = hdr.seq;
                        maxpos = page;
-               } else if (count[0] > maxcount && count[0] < 0xc0000000) {
-                       maxcount = count[0];
+               } else if (hdr.seq > maxcount && hdr.seq < 0xc0000000) {
+                       maxcount = hdr.seq;
                        maxpos = page;
-               } else if (count[0] > maxcount && count[0] > 0xc0000000
+               } else if (hdr.seq > maxcount && hdr.seq > 0xc0000000
                                        && maxcount > 0x80000000) {
-                       maxcount = count[0];
+                       maxcount = hdr.seq;
                        maxpos = page;
                }
        }
@@ -287,8 +291,9 @@ static void mtdoops_do_dump(struct kmsg_dumper *dumper,
 
        if (test_and_set_bit(0, &cxt->oops_buf_busy))
                return;
-       kmsg_dump_get_buffer(&iter, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
-                            record_size - MTDOOPS_HEADER_SIZE, NULL);
+       kmsg_dump_get_buffer(&iter, true,
+                            cxt->oops_buf + sizeof(struct mtdoops_hdr),
+                            record_size - sizeof(struct mtdoops_hdr), NULL);
        clear_bit(0, &cxt->oops_buf_busy);
 
        if (reason != KMSG_DUMP_OOPS) {