UBI: add reboot notifier
Terminate the UBI background thread prior to restarting the system.
[Artem: amended comments a little]
Signed-off-by: Kevin Cernekee <kpc.mtd@gmail.com>
Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 964a99d4..286ed59 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -41,6 +41,7 @@
#include <linux/miscdevice.h>
#include <linux/log2.h>
#include <linux/kthread.h>
+#include <linux/reboot.h>
#include "ubi.h"
/* Maximum length of the 'mtd=' parameter */
@@ -823,6 +824,34 @@
}
/**
+ * ubi_reboot_notifier - halt UBI transactions immediately prior to a reboot.
+ * @n: reboot notifier object
+ * @state: SYS_RESTART, SYS_HALT, or SYS_POWER_OFF
+ * @cmd: pointer to command string for RESTART2
+ *
+ * This function stops the UBI background thread so that the flash device
+ * remains quiescent when Linux restarts the system. Any queued work will be
+ * discarded, but this function will block until do_work() finishes if an
+ * operation is already in progress.
+ *
+ * This function solves a real-life problem observed on NOR flashes when an
+ * PEB erase operation starts, then the system is rebooted before the erase is
+ * finishes, and the boot loader gets confused and dies. So we prefer to finish
+ * the ongoing operation before rebooting.
+ */
+static int ubi_reboot_notifier(struct notifier_block *n, unsigned long state,
+ void *cmd)
+{
+ struct ubi_device *ubi;
+
+ ubi = container_of(n, struct ubi_device, reboot_notifier);
+ if (ubi->bgt_thread)
+ kthread_stop(ubi->bgt_thread);
+ ubi_sync(ubi->ubi_num);
+ return NOTIFY_DONE;
+}
+
+/**
* ubi_attach_mtd_dev - attach an MTD device.
* @mtd: MTD device description object
* @ubi_num: number to assign to the new UBI device
@@ -978,6 +1007,11 @@
wake_up_process(ubi->bgt_thread);
spin_unlock(&ubi->wl_lock);
+ /* Flash device priority is 0 - UBI needs to shut down first */
+ ubi->reboot_notifier.priority = 1;
+ ubi->reboot_notifier.notifier_call = ubi_reboot_notifier;
+ register_reboot_notifier(&ubi->reboot_notifier);
+
ubi_devices[ubi_num] = ubi;
ubi_notify_all(ubi, UBI_VOLUME_ADDED, NULL);
return ubi_num;
@@ -1049,6 +1083,7 @@
* Before freeing anything, we have to stop the background thread to
* prevent it from doing anything on this device while we are freeing.
*/
+ unregister_reboot_notifier(&ubi->reboot_notifier);
if (ubi->bgt_thread)
kthread_stop(ubi->bgt_thread);
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 70ce48b..28acd13 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -36,9 +36,9 @@
#include <linux/device.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
+#include <linux/notifier.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/ubi.h>
-#include <linux/notifier.h>
#include "ubi-media.h"
#include "scan.h"
@@ -348,6 +348,7 @@
* @bgt_thread: background thread description object
* @thread_enabled: if the background thread is enabled
* @bgt_name: background thread name
+ * @reboot_notifier: notifier to terminate background thread before rebooting
*
* @flash_size: underlying MTD device size (in bytes)
* @peb_count: count of physical eraseblocks on the MTD device
@@ -431,6 +432,7 @@
struct task_struct *bgt_thread;
int thread_enabled;
char bgt_name[sizeof(UBI_BGT_NAME_PATTERN)+2];
+ struct notifier_block reboot_notifier;
/* I/O sub-system's stuff */
long long flash_size;