mtd: mtdoops: refactor as a kmsg_dumper
The last messages which happens before a crash might contain interesting information about the crash. This patch reworks mtdoops using the kmsg_dumper support instead of a console, which simplifies the code and also includes the messages before the oops started. On oops callbacks, the MTD device write is scheduled in a work queue (to be able to use the regular mtd->write call), while panics call mtd->panic_write directly. Thus, if panic_on_oops is set, the oops will be written out during the panic. A parameter to specify which mtd device to use (number or name), as well as a flag, writable at runtime, to toggle wheter to dump oopses or only panics (since oopses can often be handled by regular syslog). The patch was massaged and amended by Artem. Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net> Reviewed-by: Anders Grafstrom <anders.grafstrom@netinsight.net> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Simon Kagstrom
David Woodhouse
parent
9507b0c838
commit
2e386e4bac
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@ -29,21 +29,34 @@
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#include <linux/sched.h>
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#include <linux/wait.h>
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#include <linux/delay.h>
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#include <linux/spinlock.h>
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#include <linux/interrupt.h>
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#include <linux/mtd/mtd.h>
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#include <linux/kmsg_dump.h>
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/* Maximum MTD partition size */
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#define MTDOOPS_MAX_MTD_SIZE (8 * 1024 * 1024)
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#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00
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#define MTDOOPS_HEADER_SIZE 8
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static unsigned long record_size = 4096;
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module_param(record_size, ulong, 0400);
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MODULE_PARM_DESC(record_size,
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"record size for MTD OOPS pages in bytes (default 4096)");
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static char mtddev[80];
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module_param_string(mtddev, mtddev, 80, 0400);
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MODULE_PARM_DESC(mtddev,
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"name or index number of the MTD device to use");
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static int dump_oops = 1;
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module_param(dump_oops, int, 0600);
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MODULE_PARM_DESC(dump_oops,
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"set to 1 to dump oopses, 0 to only dump panics (default 1)");
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static struct mtdoops_context {
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struct kmsg_dumper dump;
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int mtd_index;
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struct work_struct work_erase;
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struct work_struct work_write;
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@ -52,14 +65,8 @@ static struct mtdoops_context {
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int nextpage;
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int nextcount;
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unsigned long *oops_page_used;
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char *name;
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void *oops_buf;
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/* writecount and disabling ready are spin lock protected */
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spinlock_t writecount_lock;
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int ready;
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int writecount;
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} oops_cxt;
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static void mark_page_used(struct mtdoops_context *cxt, int page)
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@ -111,7 +118,7 @@ static int mtdoops_erase_block(struct mtdoops_context *cxt, int offset)
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remove_wait_queue(&wait_q, &wait);
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printk(KERN_WARNING "mtdoops: erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
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(unsigned long long)erase.addr,
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(unsigned long long)erase.len, mtd->name);
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(unsigned long long)erase.len, mtddev);
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return ret;
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}
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@ -141,7 +148,6 @@ static void mtdoops_inc_counter(struct mtdoops_context *cxt)
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printk(KERN_DEBUG "mtdoops: ready %d, %d (no erase)\n",
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cxt->nextpage, cxt->nextcount);
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cxt->ready = 1;
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}
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/* Scheduled work - when we can't proceed without erasing a block */
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@ -190,7 +196,6 @@ badblock:
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if (ret >= 0) {
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printk(KERN_DEBUG "mtdoops: ready %d, %d\n",
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cxt->nextpage, cxt->nextcount);
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cxt->ready = 1;
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return;
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}
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@ -208,11 +213,13 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
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{
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struct mtd_info *mtd = cxt->mtd;
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size_t retlen;
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u32 *hdr;
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int ret;
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if (cxt->writecount < record_size)
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memset(cxt->oops_buf + cxt->writecount, 0xff,
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record_size - cxt->writecount);
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/* Add mtdoops header to the buffer */
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hdr = cxt->oops_buf;
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hdr[0] = cxt->nextcount;
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hdr[1] = MTDOOPS_KERNMSG_MAGIC;
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if (panic)
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ret = mtd->panic_write(mtd, cxt->nextpage * record_size,
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@ -221,17 +228,15 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
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ret = mtd->write(mtd, cxt->nextpage * record_size,
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record_size, &retlen, cxt->oops_buf);
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cxt->writecount = 0;
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if (retlen != record_size || ret < 0)
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printk(KERN_ERR "mtdoops: write failure at %ld (%td of %ld written), error %d\n",
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cxt->nextpage * record_size, retlen, record_size, ret);
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mark_page_used(cxt, cxt->nextpage);
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memset(cxt->oops_buf, 0xff, record_size);
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mtdoops_inc_counter(cxt);
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}
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static void mtdoops_workfunc_write(struct work_struct *work)
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{
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struct mtdoops_context *cxt =
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@ -250,17 +255,18 @@ static void find_next_position(struct mtdoops_context *cxt)
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for (page = 0; page < cxt->oops_pages; page++) {
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/* Assume the page is used */
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mark_page_used(cxt, page);
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ret = mtd->read(mtd, page * record_size, 8, &retlen, (u_char *) &count[0]);
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if (retlen != 8 || (ret < 0 && ret != -EUCLEAN)) {
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printk(KERN_ERR "mtdoops: read failure at %ld (%td of 8 read), err %d\n",
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page * record_size, retlen, ret);
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ret = mtd->read(mtd, page * record_size, MTDOOPS_HEADER_SIZE,
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&retlen, (u_char *) &count[0]);
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if (retlen != MTDOOPS_HEADER_SIZE ||
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(ret < 0 && ret != -EUCLEAN)) {
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printk(KERN_ERR "mtdoops: read failure at %ld (%td of %d read), err %d\n",
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page * record_size, retlen,
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MTDOOPS_HEADER_SIZE, ret);
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continue;
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}
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if (count[0] == 0xffffffff && count[1] == 0xffffffff)
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mark_page_unused(cxt, page);
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if (count[1] != MTDOOPS_KERNMSG_MAGIC)
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continue;
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if (count[0] == 0xffffffff)
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continue;
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if (maxcount == 0xffffffff) {
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@ -291,15 +297,50 @@ static void find_next_position(struct mtdoops_context *cxt)
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mtdoops_inc_counter(cxt);
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}
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static void mtdoops_do_dump(struct kmsg_dumper *dumper,
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enum kmsg_dump_reason reason, const char *s1, unsigned long l1,
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const char *s2, unsigned long l2)
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{
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struct mtdoops_context *cxt = container_of(dumper,
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struct mtdoops_context, dump);
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unsigned long s1_start, s2_start;
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unsigned long l1_cpy, l2_cpy;
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char *dst;
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/* Only dump oopses if dump_oops is set */
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if (reason == KMSG_DUMP_OOPS && !dump_oops)
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return;
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dst = cxt->oops_buf + MTDOOPS_HEADER_SIZE; /* Skip the header */
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l2_cpy = min(l2, record_size - MTDOOPS_HEADER_SIZE);
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l1_cpy = min(l1, record_size - MTDOOPS_HEADER_SIZE - l2_cpy);
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s2_start = l2 - l2_cpy;
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s1_start = l1 - l1_cpy;
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memcpy(dst, s1 + s1_start, l1_cpy);
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memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
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/* Panics must be written immediately */
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if (reason == KMSG_DUMP_PANIC) {
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if (!cxt->mtd->panic_write)
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printk(KERN_ERR "mtdoops: Cannot write from panic without panic_write\n");
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else
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mtdoops_write(cxt, 1);
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return;
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}
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/* For other cases, schedule work to write it "nicely" */
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schedule_work(&cxt->work_write);
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}
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static void mtdoops_notify_add(struct mtd_info *mtd)
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{
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struct mtdoops_context *cxt = &oops_cxt;
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u64 mtdoops_pages = mtd->size;
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u64 mtdoops_pages = div_u64(mtd->size, record_size);
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int err;
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do_div(mtdoops_pages, record_size);
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if (cxt->name && !strcmp(mtd->name, cxt->name))
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if (!strcmp(mtd->name, mtddev))
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cxt->mtd_index = mtd->index;
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if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
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@ -310,13 +351,11 @@ static void mtdoops_notify_add(struct mtd_info *mtd)
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mtd->index);
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return;
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}
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if (mtd->erasesize < record_size) {
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printk(KERN_ERR "mtdoops: eraseblock size of MTD partition %d too small\n",
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mtd->index);
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return;
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}
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if (mtd->size > MTDOOPS_MAX_MTD_SIZE) {
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printk(KERN_ERR "mtdoops: mtd%d is too large (limit is %d MiB)\n",
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mtd->index, MTDOOPS_MAX_MTD_SIZE / 1024 / 1024);
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@ -327,7 +366,16 @@ static void mtdoops_notify_add(struct mtd_info *mtd)
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cxt->oops_page_used = vmalloc(DIV_ROUND_UP(mtdoops_pages,
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BITS_PER_LONG));
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if (!cxt->oops_page_used) {
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printk(KERN_ERR "Could not allocate page array\n");
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printk(KERN_ERR "mtdoops: could not allocate page array\n");
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return;
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}
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cxt->dump.dump = mtdoops_do_dump;
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err = kmsg_dump_register(&cxt->dump);
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if (err) {
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printk(KERN_ERR "mtdoops: registering kmsg dumper failed, error %d\n", err);
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vfree(cxt->oops_page_used);
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cxt->oops_page_used = NULL;
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return;
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}
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@ -344,116 +392,29 @@ static void mtdoops_notify_remove(struct mtd_info *mtd)
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if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
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return;
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if (kmsg_dump_unregister(&cxt->dump) < 0)
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printk(KERN_WARNING "mtdoops: could not unregister kmsg_dumper\n");
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cxt->mtd = NULL;
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flush_scheduled_work();
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}
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static void mtdoops_console_sync(void)
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{
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struct mtdoops_context *cxt = &oops_cxt;
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struct mtd_info *mtd = cxt->mtd;
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unsigned long flags;
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if (!cxt->ready || !mtd || cxt->writecount == 0)
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return;
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/*
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* Once ready is 0 and we've held the lock no further writes to the
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* buffer will happen
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*/
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spin_lock_irqsave(&cxt->writecount_lock, flags);
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if (!cxt->ready) {
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spin_unlock_irqrestore(&cxt->writecount_lock, flags);
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return;
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}
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cxt->ready = 0;
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spin_unlock_irqrestore(&cxt->writecount_lock, flags);
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if (mtd->panic_write && in_interrupt())
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/* Interrupt context, we're going to panic so try and log */
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mtdoops_write(cxt, 1);
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else
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schedule_work(&cxt->work_write);
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}
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static void
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mtdoops_console_write(struct console *co, const char *s, unsigned int count)
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{
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struct mtdoops_context *cxt = co->data;
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struct mtd_info *mtd = cxt->mtd;
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unsigned long flags;
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if (!oops_in_progress) {
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mtdoops_console_sync();
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return;
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}
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if (!cxt->ready || !mtd)
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return;
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/* Locking on writecount ensures sequential writes to the buffer */
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spin_lock_irqsave(&cxt->writecount_lock, flags);
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/* Check ready status didn't change whilst waiting for the lock */
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if (!cxt->ready) {
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spin_unlock_irqrestore(&cxt->writecount_lock, flags);
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return;
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}
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if (cxt->writecount == 0) {
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u32 *stamp = cxt->oops_buf;
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*stamp++ = cxt->nextcount;
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*stamp = MTDOOPS_KERNMSG_MAGIC;
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cxt->writecount = 8;
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}
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if (count + cxt->writecount > record_size)
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count = record_size - cxt->writecount;
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memcpy(cxt->oops_buf + cxt->writecount, s, count);
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cxt->writecount += count;
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spin_unlock_irqrestore(&cxt->writecount_lock, flags);
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if (cxt->writecount == record_size)
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mtdoops_console_sync();
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}
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static int __init mtdoops_console_setup(struct console *co, char *options)
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{
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struct mtdoops_context *cxt = co->data;
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if (cxt->mtd_index != -1 || cxt->name)
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return -EBUSY;
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if (options) {
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cxt->name = kstrdup(options, GFP_KERNEL);
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return 0;
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}
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if (co->index == -1)
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return -EINVAL;
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cxt->mtd_index = co->index;
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return 0;
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}
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static struct mtd_notifier mtdoops_notifier = {
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.add = mtdoops_notify_add,
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.remove = mtdoops_notify_remove,
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};
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static struct console mtdoops_console = {
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.name = "ttyMTD",
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.write = mtdoops_console_write,
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.setup = mtdoops_console_setup,
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.unblank = mtdoops_console_sync,
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.index = -1,
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.data = &oops_cxt,
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};
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static int __init mtdoops_console_init(void)
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static int __init mtdoops_init(void)
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{
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struct mtdoops_context *cxt = &oops_cxt;
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int mtd_index;
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char *endp;
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if (strlen(mtddev) == 0) {
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printk(KERN_ERR "mtdoops: mtd device (mtddev=name/number) must be supplied\n");
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return -EINVAL;
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}
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if ((record_size & 4095) != 0) {
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printk(KERN_ERR "mtdoops: record_size must be a multiple of 4096\n");
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return -EINVAL;
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@ -462,36 +423,44 @@ static int __init mtdoops_console_init(void)
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printk(KERN_ERR "mtdoops: record_size must be over 4096 bytes\n");
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return -EINVAL;
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}
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/* Setup the MTD device to use */
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cxt->mtd_index = -1;
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mtd_index = simple_strtoul(mtddev, &endp, 0);
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if (*endp == '\0')
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cxt->mtd_index = mtd_index;
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if (cxt->mtd_index > MAX_MTD_DEVICES) {
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printk(KERN_ERR "mtdoops: invalid mtd device number (%u) given\n",
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mtd_index);
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return -EINVAL;
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}
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cxt->oops_buf = vmalloc(record_size);
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if (!cxt->oops_buf) {
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printk(KERN_ERR "mtdoops: failed to allocate buffer workspace\n");
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return -ENOMEM;
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}
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memset(cxt->oops_buf, 0xff, record_size);
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spin_lock_init(&cxt->writecount_lock);
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INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
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INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);
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register_console(&mtdoops_console);
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register_mtd_user(&mtdoops_notifier);
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return 0;
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}
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static void __exit mtdoops_console_exit(void)
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static void __exit mtdoops_exit(void)
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{
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struct mtdoops_context *cxt = &oops_cxt;
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unregister_mtd_user(&mtdoops_notifier);
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unregister_console(&mtdoops_console);
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kfree(cxt->name);
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vfree(cxt->oops_buf);
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vfree(cxt->oops_page_used);
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}
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subsys_initcall(mtdoops_console_init);
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module_exit(mtdoops_console_exit);
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module_init(mtdoops_init);
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module_exit(mtdoops_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Richard Purdie <rpurdie@openedhand.com>");
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