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    Subject[PATCHv2] MTD: Add UBI reboot notifier
    Terminate the UBI background thread prior to restarting the system.

    Changes from v1:

    Add ubi_sync() at the end, to make sure the underlying MTD device has
    synchronized its buffers.

    Clean up comments and formatting.

    Signed-off-by: Kevin Cernekee <kpc.mtd@gmail.com>
    ---
    drivers/mtd/ubi/build.c | 30 ++++++++++++++++++++++++++++++
    drivers/mtd/ubi/ubi.h | 3 +++
    2 files changed, 33 insertions(+), 0 deletions(-)

    diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
    index 4048db8..18b42c9 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 */
    @@ -726,6 +727,29 @@ static int autoresize(struct ubi_device *ubi, int vol_id)
    }

    /**
    + * 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.
    + */
    +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
    @@ -876,6 +900,11 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
    ubi->thread_enabled = 1;
    wake_up_process(ubi->bgt_thread);

    + /* 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;
    return ubi_num;

    @@ -945,6 +974,7 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
    * 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 c055511..c8fab4a 100644
    --- a/drivers/mtd/ubi/ubi.h
    +++ b/drivers/mtd/ubi/ubi.h
    @@ -36,6 +36,7 @@
    #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>

    @@ -339,6 +340,7 @@ struct ubi_wl_entry;
    * @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
    @@ -420,6 +422,7 @@ struct ubi_device {
    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;
    --
    1.6.3.1


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