schedule_work doesn't enforce that the work be done before prepare_namespace
tries to find a rootfs. If device probing is fast enough, we can panic with
"VFS: Unable to mount root fs" before the mtdconcat comes up.
prepare_namespace calls wait_for_device_probe first, which waits for all async
calls in the default domain (eg. scheduled with async_schedule) to finish.
The last catch is that plain mtd_device_register tries to load partition parsing
modules and module loading is prohibited in async calls. The fix is to prevent
mtd_device_register from trying any partition parsers by calling
mtd_device_parse_register directly and passing an empty parser list.
Signed-off-by: Catalin Patulea <c...@vv.carleton.ca>
---
.../ar71xx/files/arch/mips/ath79/dev-m25p80.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/target/linux/ar71xx/files/arch/mips/ath79/dev-m25p80.c
b/target/linux/ar71xx/files/arch/mips/ath79/dev-m25p80.c
index 9323b31..8cdb2f6 100644
--- a/target/linux/ar71xx/files/arch/mips/ath79/dev-m25p80.c
+++ b/target/linux/ar71xx/files/arch/mips/ath79/dev-m25p80.c
@@ -6,6 +6,7 @@
* by the Free Software Foundation.
*/
+#include <linux/async.h>
#include <linux/init.h>
#include <linux/spi/spi.h>
#include <linux/spi/flash.h>
@@ -59,15 +60,20 @@ void __init ath79_register_m25p80(struct
flash_platform_data *pdata)
static struct flash_platform_data *multi_pdata;
static struct mtd_info *concat_devs[2] = { NULL, NULL };
-static struct work_struct mtd_concat_work;
-static void mtd_concat_add_work(struct work_struct *work)
+static void mtd_concat_add_async(void *unused_data,
+ async_cookie_t unused_cookie)
{
+ /* don't try to load partition parser modules, module loading is
+ * disallowed in async */
+ const char *types[] = {NULL};
+
struct mtd_info *mtd;
mtd = mtd_concat_create(concat_devs, ARRAY_SIZE(concat_devs), "flash");
- mtd_device_register(mtd, multi_pdata->parts, multi_pdata->nr_parts);
+ mtd_device_parse_register(mtd, types, NULL, multi_pdata->parts,
+ multi_pdata->nr_parts);
}
static void mtd_concat_add(struct mtd_info *mtd)
@@ -88,8 +94,9 @@ static void mtd_concat_add(struct mtd_info *mtd)
return;
registered = true;
- INIT_WORK(&mtd_concat_work, mtd_concat_add_work);
- schedule_work(&mtd_concat_work);
+
+ /* make sure we complete before prepare_namespace looks for rootfs */
+ async_schedule(&mtd_concat_add_async, NULL);
}
static void mtd_concat_remove(struct mtd_info *mtd)
--
1.7.9.5
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