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>
diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 64772dc..a714ec4 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -29,21 +29,34 @@
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
-#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/mtd/mtd.h>
+#include <linux/kmsg_dump.h>
/* 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,
"record size for MTD OOPS pages in bytes (default 4096)");
+static char mtddev[80];
+module_param_string(mtddev, mtddev, 80, 0400);
+MODULE_PARM_DESC(mtddev,
+ "name or index number of the MTD device to use");
+
+static int dump_oops = 1;
+module_param(dump_oops, int, 0600);
+MODULE_PARM_DESC(dump_oops,
+ "set to 1 to dump oopses, 0 to only dump panics (default 1)");
+
static struct mtdoops_context {
+ struct kmsg_dumper dump;
+
int mtd_index;
struct work_struct work_erase;
struct work_struct work_write;
@@ -52,14 +65,8 @@
int nextpage;
int nextcount;
unsigned long *oops_page_used;
- char *name;
void *oops_buf;
-
- /* writecount and disabling ready are spin lock protected */
- spinlock_t writecount_lock;
- int ready;
- int writecount;
} oops_cxt;
static void mark_page_used(struct mtdoops_context *cxt, int page)
@@ -111,7 +118,7 @@
remove_wait_queue(&wait_q, &wait);
printk(KERN_WARNING "mtdoops: erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
(unsigned long long)erase.addr,
- (unsigned long long)erase.len, mtd->name);
+ (unsigned long long)erase.len, mtddev);
return ret;
}
@@ -141,7 +148,6 @@
printk(KERN_DEBUG "mtdoops: ready %d, %d (no erase)\n",
cxt->nextpage, cxt->nextcount);
- cxt->ready = 1;
}
/* Scheduled work - when we can't proceed without erasing a block */
@@ -190,7 +196,6 @@
if (ret >= 0) {
printk(KERN_DEBUG "mtdoops: ready %d, %d\n",
cxt->nextpage, cxt->nextcount);
- cxt->ready = 1;
return;
}
@@ -208,11 +213,13 @@
{
struct mtd_info *mtd = cxt->mtd;
size_t retlen;
+ u32 *hdr;
int ret;
- if (cxt->writecount < record_size)
- memset(cxt->oops_buf + cxt->writecount, 0xff,
- record_size - cxt->writecount);
+ /* Add mtdoops header to the buffer */
+ hdr = cxt->oops_buf;
+ hdr[0] = cxt->nextcount;
+ hdr[1] = MTDOOPS_KERNMSG_MAGIC;
if (panic)
ret = mtd->panic_write(mtd, cxt->nextpage * record_size,
@@ -221,17 +228,15 @@
ret = mtd->write(mtd, cxt->nextpage * record_size,
record_size, &retlen, cxt->oops_buf);
- cxt->writecount = 0;
-
if (retlen != record_size || ret < 0)
printk(KERN_ERR "mtdoops: write failure at %ld (%td of %ld written), error %d\n",
cxt->nextpage * record_size, retlen, record_size, ret);
mark_page_used(cxt, cxt->nextpage);
+ memset(cxt->oops_buf, 0xff, record_size);
mtdoops_inc_counter(cxt);
}
-
static void mtdoops_workfunc_write(struct work_struct *work)
{
struct mtdoops_context *cxt =
@@ -250,17 +255,18 @@
for (page = 0; page < cxt->oops_pages; page++) {
/* Assume the page is used */
mark_page_used(cxt, page);
- ret = mtd->read(mtd, page * record_size, 8, &retlen, (u_char *) &count[0]);
- if (retlen != 8 || (ret < 0 && ret != -EUCLEAN)) {
- printk(KERN_ERR "mtdoops: read failure at %ld (%td of 8 read), err %d\n",
- page * record_size, retlen, ret);
+ ret = mtd->read(mtd, page * record_size, MTDOOPS_HEADER_SIZE,
+ &retlen, (u_char *) &count[0]);
+ if (retlen != MTDOOPS_HEADER_SIZE ||
+ (ret < 0 && ret != -EUCLEAN)) {
+ printk(KERN_ERR "mtdoops: read failure at %ld (%td of %d read), err %d\n",
+ page * record_size, retlen,
+ MTDOOPS_HEADER_SIZE, ret);
continue;
}
if (count[0] == 0xffffffff && count[1] == 0xffffffff)
mark_page_unused(cxt, page);
- if (count[1] != MTDOOPS_KERNMSG_MAGIC)
- continue;
if (count[0] == 0xffffffff)
continue;
if (maxcount == 0xffffffff) {
@@ -291,15 +297,50 @@
mtdoops_inc_counter(cxt);
}
+static void mtdoops_do_dump(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason, const char *s1, unsigned long l1,
+ const char *s2, unsigned long l2)
+{
+ struct mtdoops_context *cxt = container_of(dumper,
+ struct mtdoops_context, dump);
+ unsigned long s1_start, s2_start;
+ unsigned long l1_cpy, l2_cpy;
+ char *dst;
+
+ /* Only dump oopses if dump_oops is set */
+ if (reason == KMSG_DUMP_OOPS && !dump_oops)
+ return;
+
+ dst = cxt->oops_buf + MTDOOPS_HEADER_SIZE; /* Skip the header */
+ l2_cpy = min(l2, record_size - MTDOOPS_HEADER_SIZE);
+ l1_cpy = min(l1, record_size - MTDOOPS_HEADER_SIZE - l2_cpy);
+
+ s2_start = l2 - l2_cpy;
+ s1_start = l1 - l1_cpy;
+
+ memcpy(dst, s1 + s1_start, l1_cpy);
+ memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
+
+ /* Panics must be written immediately */
+ if (reason == KMSG_DUMP_PANIC) {
+ if (!cxt->mtd->panic_write)
+ printk(KERN_ERR "mtdoops: Cannot write from panic without panic_write\n");
+ else
+ mtdoops_write(cxt, 1);
+ return;
+ }
+
+ /* For other cases, schedule work to write it "nicely" */
+ schedule_work(&cxt->work_write);
+}
static void mtdoops_notify_add(struct mtd_info *mtd)
{
struct mtdoops_context *cxt = &oops_cxt;
- u64 mtdoops_pages = mtd->size;
+ u64 mtdoops_pages = div_u64(mtd->size, record_size);
+ int err;
- do_div(mtdoops_pages, record_size);
-
- if (cxt->name && !strcmp(mtd->name, cxt->name))
+ if (!strcmp(mtd->name, mtddev))
cxt->mtd_index = mtd->index;
if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
@@ -310,13 +351,11 @@
mtd->index);
return;
}
-
if (mtd->erasesize < record_size) {
printk(KERN_ERR "mtdoops: eraseblock size of MTD partition %d too small\n",
mtd->index);
return;
}
-
if (mtd->size > MTDOOPS_MAX_MTD_SIZE) {
printk(KERN_ERR "mtdoops: mtd%d is too large (limit is %d MiB)\n",
mtd->index, MTDOOPS_MAX_MTD_SIZE / 1024 / 1024);
@@ -327,7 +366,16 @@
cxt->oops_page_used = vmalloc(DIV_ROUND_UP(mtdoops_pages,
BITS_PER_LONG));
if (!cxt->oops_page_used) {
- printk(KERN_ERR "Could not allocate page array\n");
+ printk(KERN_ERR "mtdoops: could not allocate page array\n");
+ return;
+ }
+
+ cxt->dump.dump = mtdoops_do_dump;
+ err = kmsg_dump_register(&cxt->dump);
+ if (err) {
+ printk(KERN_ERR "mtdoops: registering kmsg dumper failed, error %d\n", err);
+ vfree(cxt->oops_page_used);
+ cxt->oops_page_used = NULL;
return;
}
@@ -344,116 +392,29 @@
if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
return;
+ if (kmsg_dump_unregister(&cxt->dump) < 0)
+ printk(KERN_WARNING "mtdoops: could not unregister kmsg_dumper\n");
+
cxt->mtd = NULL;
flush_scheduled_work();
}
-static void mtdoops_console_sync(void)
-{
- struct mtdoops_context *cxt = &oops_cxt;
- struct mtd_info *mtd = cxt->mtd;
- unsigned long flags;
-
- if (!cxt->ready || !mtd || cxt->writecount == 0)
- return;
-
- /*
- * Once ready is 0 and we've held the lock no further writes to the
- * buffer will happen
- */
- spin_lock_irqsave(&cxt->writecount_lock, flags);
- if (!cxt->ready) {
- spin_unlock_irqrestore(&cxt->writecount_lock, flags);
- return;
- }
- cxt->ready = 0;
- spin_unlock_irqrestore(&cxt->writecount_lock, flags);
-
- if (mtd->panic_write && in_interrupt())
- /* Interrupt context, we're going to panic so try and log */
- mtdoops_write(cxt, 1);
- else
- schedule_work(&cxt->work_write);
-}
-
-static void
-mtdoops_console_write(struct console *co, const char *s, unsigned int count)
-{
- struct mtdoops_context *cxt = co->data;
- struct mtd_info *mtd = cxt->mtd;
- unsigned long flags;
-
- if (!oops_in_progress) {
- mtdoops_console_sync();
- return;
- }
-
- if (!cxt->ready || !mtd)
- return;
-
- /* Locking on writecount ensures sequential writes to the buffer */
- spin_lock_irqsave(&cxt->writecount_lock, flags);
-
- /* Check ready status didn't change whilst waiting for the lock */
- if (!cxt->ready) {
- spin_unlock_irqrestore(&cxt->writecount_lock, flags);
- return;
- }
-
- if (cxt->writecount == 0) {
- u32 *stamp = cxt->oops_buf;
- *stamp++ = cxt->nextcount;
- *stamp = MTDOOPS_KERNMSG_MAGIC;
- cxt->writecount = 8;
- }
-
- if (count + cxt->writecount > record_size)
- count = record_size - cxt->writecount;
-
- memcpy(cxt->oops_buf + cxt->writecount, s, count);
- cxt->writecount += count;
-
- spin_unlock_irqrestore(&cxt->writecount_lock, flags);
-
- if (cxt->writecount == record_size)
- mtdoops_console_sync();
-}
-
-static int __init mtdoops_console_setup(struct console *co, char *options)
-{
- struct mtdoops_context *cxt = co->data;
-
- if (cxt->mtd_index != -1 || cxt->name)
- return -EBUSY;
- if (options) {
- cxt->name = kstrdup(options, GFP_KERNEL);
- return 0;
- }
- if (co->index == -1)
- return -EINVAL;
-
- cxt->mtd_index = co->index;
- return 0;
-}
static struct mtd_notifier mtdoops_notifier = {
.add = mtdoops_notify_add,
.remove = mtdoops_notify_remove,
};
-static struct console mtdoops_console = {
- .name = "ttyMTD",
- .write = mtdoops_console_write,
- .setup = mtdoops_console_setup,
- .unblank = mtdoops_console_sync,
- .index = -1,
- .data = &oops_cxt,
-};
-
-static int __init mtdoops_console_init(void)
+static int __init mtdoops_init(void)
{
struct mtdoops_context *cxt = &oops_cxt;
+ int mtd_index;
+ char *endp;
+ if (strlen(mtddev) == 0) {
+ printk(KERN_ERR "mtdoops: mtd device (mtddev=name/number) must be supplied\n");
+ return -EINVAL;
+ }
if ((record_size & 4095) != 0) {
printk(KERN_ERR "mtdoops: record_size must be a multiple of 4096\n");
return -EINVAL;
@@ -462,36 +423,44 @@
printk(KERN_ERR "mtdoops: record_size must be over 4096 bytes\n");
return -EINVAL;
}
+
+ /* Setup the MTD device to use */
cxt->mtd_index = -1;
+ mtd_index = simple_strtoul(mtddev, &endp, 0);
+ if (*endp == '\0')
+ cxt->mtd_index = mtd_index;
+ if (cxt->mtd_index > MAX_MTD_DEVICES) {
+ printk(KERN_ERR "mtdoops: invalid mtd device number (%u) given\n",
+ mtd_index);
+ return -EINVAL;
+ }
+
cxt->oops_buf = vmalloc(record_size);
if (!cxt->oops_buf) {
printk(KERN_ERR "mtdoops: failed to allocate buffer workspace\n");
return -ENOMEM;
}
+ memset(cxt->oops_buf, 0xff, record_size);
- spin_lock_init(&cxt->writecount_lock);
INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);
- register_console(&mtdoops_console);
register_mtd_user(&mtdoops_notifier);
return 0;
}
-static void __exit mtdoops_console_exit(void)
+static void __exit mtdoops_exit(void)
{
struct mtdoops_context *cxt = &oops_cxt;
unregister_mtd_user(&mtdoops_notifier);
- unregister_console(&mtdoops_console);
- kfree(cxt->name);
vfree(cxt->oops_buf);
vfree(cxt->oops_page_used);
}
-subsys_initcall(mtdoops_console_init);
-module_exit(mtdoops_console_exit);
+module_init(mtdoops_init);
+module_exit(mtdoops_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Richard Purdie <rpurdie@openedhand.com>");
