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SubjectRe: [PATCH] afs: Add missing memory barriers in afs_manage_cell()
On Mon, Nov 26, 2018 at 05:44:12PM +0100, Andrea Parri wrote:
> As the comments for wake_up_bit() and waitqueue_active() point out,
> the barriers are needed to order the clearing of the _FL_NOT_READY
> bit and the waitqueue_active() load; match the implicit barrier in
> prepare_to_wait().
>
> Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>

Hi David, do you have any feedback on this?

Andrea


> ---
> fs/afs/cell.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/afs/cell.c b/fs/afs/cell.c
> index cf445dbd5f2e0..a9488abe56029 100644
> --- a/fs/afs/cell.c
> +++ b/fs/afs/cell.c
> @@ -637,6 +637,7 @@ static void afs_manage_cell(struct work_struct *work)
> cell->state = AFS_CELL_ACTIVE;
> smp_wmb();
> clear_bit(AFS_CELL_FL_NOT_READY, &cell->flags);
> + smp_mb__after_atomic(); /* see comment for wake_up_bit() */
> wake_up_bit(&cell->flags, AFS_CELL_FL_NOT_READY);
> goto again;
>
> @@ -678,6 +679,7 @@ static void afs_manage_cell(struct work_struct *work)
> cell->state = AFS_CELL_ACTIVE;
> smp_wmb();
> clear_bit(AFS_CELL_FL_NOT_READY, &cell->flags);
> + smp_mb__after_atomic(); /* see comment for wake_up_bit() */
> wake_up_bit(&cell->flags, AFS_CELL_FL_NOT_READY);
> _leave(" [deact->act]");
> return;
> --
> 2.17.1
>

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