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    SubjectRe: [PATCH 2/6] UBI: Fastmap: Ensure that only one fastmap work is scheduled
    On 11/24/2014 3:20 PM, Richard Weinberger wrote:
    > If the WL pool runs out of PEBs we schedule a fastmap write
    > to refill it as soon as possible.
    > Ensure that only one at a time is scheduled otherwise we might end in
    > a fastmap write storm because writing the fastmap can schedule another
    > write if bitflips are detected.
    >

    Reviewed-by: Tanya Brokhman <tlinder@codeaurora.org>

    > Signed-off-by: Richard Weinberger <richard@nod.at>
    > ---
    > drivers/mtd/ubi/ubi.h | 4 +++-
    > drivers/mtd/ubi/wl.c | 8 +++++++-
    > 2 files changed, 10 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
    > index f80ffab..04c4c05 100644
    > --- a/drivers/mtd/ubi/ubi.h
    > +++ b/drivers/mtd/ubi/ubi.h
    > @@ -427,6 +427,7 @@ struct ubi_debug_info {
    > * @fm_size: fastmap size in bytes
    > * @fm_sem: allows ubi_update_fastmap() to block EBA table changes
    > * @fm_work: fastmap work queue
    > + * @fm_work_scheduled: non-zero if fastmap work was scheduled
    > *
    > * @used: RB-tree of used physical eraseblocks
    > * @erroneous: RB-tree of erroneous used physical eraseblocks
    > @@ -438,7 +439,7 @@ struct ubi_debug_info {
    > * @pq_head: protection queue head
    > * @wl_lock: protects the @used, @free, @pq, @pq_head, @lookuptbl, @move_from,
    > * @move_to, @move_to_put @erase_pending, @wl_scheduled, @works,
    > - * @erroneous, and @erroneous_peb_count fields
    > + * @erroneous, @erroneous_peb_count, and @fm_work_scheduled fields
    > * @move_mutex: serializes eraseblock moves
    > * @work_sem: used to wait for all the scheduled works to finish and prevent
    > * new works from being submitted
    > @@ -533,6 +534,7 @@ struct ubi_device {
    > void *fm_buf;
    > size_t fm_size;
    > struct work_struct fm_work;
    > + int fm_work_scheduled;
    >
    > /* Wear-leveling sub-system's stuff */
    > struct rb_root used;
    > diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
    > index 834f6fe..7f135df 100644
    > --- a/drivers/mtd/ubi/wl.c
    > +++ b/drivers/mtd/ubi/wl.c
    > @@ -149,6 +149,9 @@ static void update_fastmap_work_fn(struct work_struct *wrk)
    > {
    > struct ubi_device *ubi = container_of(wrk, struct ubi_device, fm_work);
    > ubi_update_fastmap(ubi);
    > + spin_lock(&ubi->wl_lock);
    > + ubi->fm_work_scheduled = 0;
    > + spin_unlock(&ubi->wl_lock);
    > }
    >
    > /**
    > @@ -660,7 +663,10 @@ static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
    > /* We cannot update the fastmap here because this
    > * function is called in atomic context.
    > * Let's fail here and refill/update it as soon as possible. */
    > - schedule_work(&ubi->fm_work);
    > + if (!ubi->fm_work_scheduled) {
    > + ubi->fm_work_scheduled = 1;
    > + schedule_work(&ubi->fm_work);
    > + }
    > return NULL;
    > } else {
    > pnum = pool->pebs[pool->used++];
    >


    Thanks,
    Tanya Brokhman
    --
    Qualcomm Israel, on behalf of Qualcomm Innovation Center, Inc.
    The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
    a Linux Foundation Collaborative Project


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