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    SubjectRe: [PATCH v3] Fixes: 07928d9bfc81 ("padata: Remove broken queue flushing")
    Hi,

    On Sat, Oct 07, 2023 at 11:52:33AM +0800, Wang Jinchao wrote:
    > Signed-off-by: Wang Jinchao <wangjinchao@xfusion.com>

    The Fixes: tag should be near your Signed-off-by:, and the subject of
    the patch should be something descriptive like

    padata: Fix refcnt handling in padata_free_shell()

    Here's some documentation about this:

    https://docs.kernel.org/process/5.Posting.html#patch-formatting-and-changelogs

    > Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
    > ---
    > V3:
    > Include Daniel's ack
    >
    > V2: https://lore.kernel.org/all/ZRTLHY5A+VqIKhA2@fedora/
    > To satisfy Sparse, use rcu_dereference_protected.
    > Reported-by: kernel test robot <lkp@intel.com>
    > Closes: https://lore.kernel.org/oe-kbuild-all/202309270829.xHgTOMKw-lkp@intel.com/

    These two tags can also go near your SoB.

    > V1: https://lore.kernel.org/all/ZRE4XvOOhz4HSOgR@fedora/
    >
    > kernel/padata.c | 6 +++++-
    > 1 file changed, 5 insertions(+), 1 deletion(-)
    >
    > diff --git a/kernel/padata.c b/kernel/padata.c
    > index 222d60195de6..79d04a97ded6 100644
    > --- a/kernel/padata.c
    > +++ b/kernel/padata.c
    > @@ -1102,12 +1102,16 @@ EXPORT_SYMBOL(padata_alloc_shell);
    > */
    > void padata_free_shell(struct padata_shell *ps)
    > {
    > + struct parallel_data *pd;
    > +
    > if (!ps)
    > return;
    >
    > mutex_lock(&ps->pinst->lock);
    > list_del(&ps->list);
    > - padata_free_pd(rcu_dereference_protected(ps->pd, 1));
    > + pd = rcu_dereference_protected(ps->pd, 1);
    > + if (refcount_dec_and_test(&pd->refcnt))
    > + padata_free_pd(rcu_dereference_protected(ps->pd, 1));

    As Herbert points out, this version changes the code by
    rcu-dereferencing pd twice. Usually previous acks are dropped when
    introducing new changes, but you can have it back by only
    rcu-dereferencing once and addressing the other comments above.

    > mutex_unlock(&ps->pinst->lock);
    >
    > kfree(ps);
    > --
    > 2.40.0
    >

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