linux-kernel - Re: [PATCH] lightnvm: pblk: stop taking the free lock in in pblk_lines

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Message-Id: <251D7CB9-A9B0-4474-85A0-B0C23DB31272@javigon.com>
Date:   Thu, 24 Jan 2019 14:19:52 +0100
From:   Javier González <javier@...igon.com>
To:     Hans Holmberg <hans@...tronix.com>
Cc:     Matias Bjørling <mb@...htnvm.io>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hans Holmberg <hans.holmberg@...xlabs.com>
Subject: Re: [PATCH] lightnvm: pblk: stop taking the free lock in in
 pblk_lines_free

> On 22 Jan 2019, at 11.15, hans@...tronix.com wrote:
> 
> From: Hans Holmberg <hans.holmberg@...xlabs.com>
> 
> 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.
> 
> As there is no point of grabbing the free lock when pblk has shut down,
> remove the lock.
> 
> Signed-off-by: Hans Holmberg <hans.holmberg@...xlabs.com>
> ---
> drivers/lightnvm/pblk-init.c | 2 --
> 1 file changed, 2 deletions(-)
> 
> 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;
> 
> -	spin_lock(&l_mg->free_lock);
> 	for (i = 0; i < l_mg->nr_lines; i++) {
> 		line = &pblk->lines[i];
> 
> 		pblk_line_free(line);
> 		pblk_line_meta_free(l_mg, line);
> 	}
> -	spin_unlock(&l_mg->free_lock);
> 
> 	pblk_line_mg_free(pblk);
> 
> --
> 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 González <javier@...igon.com>


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