[PATCH/RFC v5 5/5]: mtdoops: refactor as a dump_device

Simon Kagstrom
2009-10-13T13:22:57Z

The last messages which happens before a crash might contain interesting
information about the crash. This patch reworks mtdoops using the
dump_device support instead of a console, which simplifies the code and
includes also messages before the oops started.

It registers handlers for both oopses and panics. On oopses, the 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 to toggle wheter to dump oopses or only panics (since oopses
can often be handled by regular syslog).

Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
---
drivers/mtd/mtdoops.c | 218 +++++++++++++++++++++----------------------------
1 files changed, 92 insertions(+), 126 deletions(-)

diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index c2a3b5c..920ce4f 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -29,10 +29,10 @@
#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/log2.h>
+#include <linux/dump_device.h>

#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00

@@ -41,7 +41,19 @@ module_param(record_size, ulong, 0);
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, 0600);
+MODULE_PARM_DESC(mtddev,
+ "name or index number of the MTD device to use");
+
+static int dump_oops = 1;
+module_param(dump_oops, int, 0);
+MODULE_PARM_DESC(dump_oops,
+ "set to 1 to dump oopses, 0 to only dump panics (default 1)");
+
static struct mtdoops_context {
+ struct dump_device dump;
+
int mtd_index;
struct work_struct work_erase;
struct work_struct work_write;
@@ -50,14 +62,9 @@ static struct mtdoops_context {
int nextpage;
int nextcount;
u32 *oops_page_used;
- char *name;
+ const 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)
@@ -148,7 +155,6 @@ static void mtdoops_inc_counter(struct mtdoops_context *cxt)

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 */
@@ -197,7 +203,6 @@ badblock:
if (ret >= 0) {
printk(KERN_DEBUG "mtdoops: ready %d, %d\n",
cxt->nextpage, cxt->nextcount);
- cxt->ready = 1;
return;
}

@@ -215,11 +220,13 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
{
struct mtd_info *mtd = cxt->mtd;
size_t retlen;
+ u32 *stamp;
int ret;

- if (cxt->writecount < record_size)
- memset(cxt->oops_buf + cxt->writecount, 0xff,
- record_size - cxt->writecount);
+ /* Add mtdoops header to the buffer */
+ stamp = cxt->oops_buf;
+ *stamp++ = cxt->nextcount;
+ *stamp = MTDOOPS_KERNMSG_MAGIC;

if (panic)
ret = mtd->panic_write(mtd, cxt->nextpage * record_size,
@@ -228,8 +235,6 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
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);
@@ -238,7 +243,6 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
mtdoops_inc_counter(cxt);
}

-
static void mtdoops_workfunc_write(struct work_struct *work)
{
struct mtdoops_context *cxt =
@@ -294,11 +298,9 @@ static void find_next_position(struct mtdoops_context *cxt)
if (unclean_pages != 0) {
printk(KERN_INFO "mtdoops: cleaning area\n");
schedule_work(&cxt->work_erase);
- } else {
+ } else
printk(KERN_DEBUG "mtdoops: ready %d, %d (clean)\n",
cxt->nextpage, cxt->nextcount);
- cxt->ready = 1;
- }
return;
}

@@ -308,13 +310,55 @@ static void find_next_position(struct mtdoops_context *cxt)
mtdoops_inc_counter(cxt);
}

+static void mtdoops_copy_buffer(struct mtdoops_context *cxt,
+ const char *s1, unsigned long l1,
+ const char *s2, unsigned long l2)
+{
+ unsigned long l1_cpy = min(l1, record_size - 8);
+ unsigned long l2_cpy = min(l2 - l1_cpy, record_size - l1_cpy - 8);
+ char *dst = cxt->oops_buf + 8; /* Skip the header */
+
+ memcpy(dst, s1, l1_cpy);
+ memcpy(dst + l1_cpy, s2, l2_cpy);
+}
+
+static void mtdoops_oops(struct dump_device *dump,
+ const char *s1, unsigned long l1,
+ const char *s2, unsigned long l2)
+{
+ struct mtdoops_context *cxt = dump->priv;
+
+ mtdoops_copy_buffer(cxt, s1, l1, s2, l2);
+
+ /* Write when done */
+ schedule_work(&cxt->work_write);
+}
+
+static void mtdoops_panic(struct dump_device *dump,
+ const char *s1, unsigned long l1,
+ const char *s2, unsigned long l2)
+{
+ struct mtdoops_context *cxt = dump->priv;
+
+ mtdoops_copy_buffer(cxt, s1, l1, s2, l2);
+ /* Must be written immediately */
+ if (cxt->mtd->panic_write)
+ mtdoops_write(cxt, 1);
+ else
+ printk(KERN_ERR "mtdoops: Cannot write from panic without panic_write\n");
+}
+
+static int mtdoops_setup(struct dump_device *dump)
+{
+ return 0;
+}

static void mtdoops_notify_add(struct mtd_info *mtd)
{
struct mtdoops_context *cxt = &oops_cxt;
- u64 mtdoops_pages = mtd->size;
+ u64 mtdoops_records = mtd->size;

- do_div(mtdoops_pages, record_size);
+ do_div(mtdoops_records, record_size);

if (cxt->name && !strcmp(mtd->name, cxt->name))
cxt->mtd_index = mtd->index;
@@ -335,7 +379,7 @@ static void mtdoops_notify_add(struct mtd_info *mtd)
}

/* oops_page_used is a bit field */
- cxt->oops_page_used = vmalloc(DIV_ROUND_UP(mtdoops_pages,
+ cxt->oops_page_used = vmalloc(DIV_ROUND_UP(mtdoops_records,
8 * sizeof(u32)));
if (!cxt->oops_page_used) {
printk(KERN_ERR "Could not allocate page array\n");
@@ -349,6 +393,11 @@ static void mtdoops_notify_add(struct mtd_info *mtd)

find_next_position(cxt);

+ cxt->dump.setup = mtdoops_setup;
+ if (dump_oops)
+ cxt->dump.oops = mtdoops_oops;
+ cxt->dump.panic = mtdoops_panic;
+ register_dumpdevice(&cxt->dump, cxt);
printk(KERN_INFO "mtdoops: Attached to MTD device %d\n", mtd->index);
}

@@ -359,116 +408,27 @@ static void mtdoops_notify_remove(struct mtd_info *mtd)
if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
return;

+ unregister_dumpdevice(&cxt->dump);
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() || panic_on_oops))
- /* 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 must be supplied\n");
+ return -EINVAL;
+ }
if (!is_power_of_2(record_size)) {
printk(KERN_ERR "mtdoops: record_size must be a power of two\n");
return -EINVAL;
@@ -477,37 +437,43 @@ static int __init mtdoops_console_init(void)
printk(KERN_ERR "mtdoops: record_size must be over 4096 bytes\n");
return -EINVAL;
}
+
+ /* Setup the MTD device to use */
+ cxt->name = mtddev;
cxt->mtd_index = -1;
+ mtd_index = simple_strtoul(mtddev, &endp, 0);
+ if (endp != mtddev)
+ cxt->mtd_index = mtd_index;
+
cxt->oops_buf = vmalloc(record_size);
if (!cxt->oops_buf) {
- printk(KERN_ERR "mtdoops: failed to allocate buffer workspace\n");
+ printk(KERN_ERR "Failed to allocate mtdoops write buffer workspace\n");
+ vfree(cxt->oops_buf);
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);
if (cxt->oops_page_used)
vfree(cxt->oops_page_used);
+ vfree(cxt->oops_buf);
}

-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>");
--
1.6.0.4