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From:   =?utf-8?Q?Javier_Gonz=C3=A1lez?= <javier@javigon.com>
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Subject: Re: [PATCH] lightnvm: pblk: stop taking the free lock in in
 pblk_lines_free
Date:   Thu, 24 Jan 2019 14:19:52 +0100
In-Reply-To: <20190122101531.30893-1-hans@owltronix.com>
Cc:     =?utf-8?Q?Matias_Bj=C3=B8rling?= <mb@lightnvm.io>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        Hans Holmberg <hans.holmberg@cnexlabs.com>
To:     Hans Holmberg <hans@owltronix.com>
References: <20190122101531.30893-1-hans@owltronix.com>
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> On 22 Jan 2019, at 11.15, hans@owltronix.com wrote:
>=20
> From: Hans Holmberg <hans.holmberg@cnexlabs.com>
>=20
> pblk_line_meta_free might sleep (it can end up calling vfree, =
depending
> on how we allocate lba lists), and this can lead to a BUG()
> if we wake up on a different cpu and release the lock.
>=20
> As there is no point of grabbing the free lock when pblk has shut =
down,
> remove the lock.
>=20
> Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
> ---
> drivers/lightnvm/pblk-init.c | 2 --
> 1 file changed, 2 deletions(-)
>=20
> diff --git a/drivers/lightnvm/pblk-init.c =
b/drivers/lightnvm/pblk-init.c
> index f9a3e47b6a93..eb0135c77805 100644
> --- a/drivers/lightnvm/pblk-init.c
> +++ b/drivers/lightnvm/pblk-init.c
> @@ -584,14 +584,12 @@ static void pblk_lines_free(struct pblk *pblk)
> 	struct pblk_line *line;
> 	int i;
>=20
> -	spin_lock(&l_mg->free_lock);
> 	for (i =3D 0; i < l_mg->nr_lines; i++) {
> 		line =3D &pblk->lines[i];
>=20
> 		pblk_line_free(line);
> 		pblk_line_meta_free(l_mg, line);
> 	}
> -	spin_unlock(&l_mg->free_lock);
>=20
> 	pblk_line_mg_free(pblk);
>=20
> --
> 2.17.1

Can you add a comment too indicating that this is only safe on a single
threaded shutdown?

Otherwise the patch looks good.

Reviewed-by: Javier Gonz=C3=A1lez <javier@javigon.com>


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