linux-kernel - Re: [PATCH v3 3/5] mtd: rawnand: brcmnand: Fix crash during the panic

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Date:   Tue, 4 Jul 2023 17:23:23 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     William Zhang <william.zhang@...adcom.com>
Cc:     Broadcom Kernel List <bcm-kernel-feedback-list@...adcom.com>,
        Linux MTD List <linux-mtd@...ts.infradead.org>,
        f.fainelli@...il.com, rafal@...ecki.pl, kursad.oney@...adcom.com,
        joel.peshkin@...adcom.com, computersforpeace@...il.com,
        anand.gore@...adcom.com, dregan@...l.com, kamal.dasu@...adcom.com,
        tomer.yacoby@...adcom.com, dan.beygelman@...adcom.com,
        Florian Fainelli <florian.fainelli@...adcom.com>,
        linux-kernel@...r.kernel.org,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Kamal Dasu <kdasu.kdev@...il.com>
Subject: Re: [PATCH v3 3/5] mtd: rawnand: brcmnand: Fix crash during the
 panic_write

Hi William,

william.zhang@...adcom.com wrote on Tue, 27 Jun 2023 12:37:36 -0700:

> During the panic write path to execute another nand command, if

"When executing a NAND command within the panic write path, wait for any
pending command instead of calling BUG_ON to avoid crashing while
(already) crashing."

> there is a pending command, we should wait for the command instead of
> calling BUG_ON so we don't crash while crashing.
> 
> Fixes: 27c5b17cd1b1 ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
> Signed-off-by: William Zhang <william.zhang@...adcom.com>
> Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>
> Reviewed-by: Kursad Oney <kursad.oney@...adcom.com>
> Reviewed-by: Kamal Dasu <kamal.dasu@...adcom.com>
> ---
> 
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/mtd/nand/raw/brcmnand/brcmnand.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> index 37c2c7cfa00e..ea03104692bf 100644
> --- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
> @@ -1608,7 +1608,17 @@ static void brcmnand_send_cmd(struct brcmnand_host *host, int cmd)
>  
>  	dev_dbg(ctrl->dev, "send native cmd %d addr 0x%llx\n", cmd, cmd_addr);
>  
> -	BUG_ON(ctrl->cmd_pending != 0);
> +	/*
> +	 * If we came here through _panic_write and there is a pending
> +	 * command, try to wait for it. If it times out, rather than
> +	 * hitting BUG_ON, just return so we don't crash while crashing.
> +	 */
> +	if (oops_in_progress) {
> +		if (ctrl->cmd_pending &&
> +			bcmnand_ctrl_poll_status(ctrl, NAND_CTRL_RDY, NAND_CTRL_RDY, 0))
> +			return;
> +	} else
> +		BUG_ON(ctrl->cmd_pending != 0);
>  	ctrl->cmd_pending = cmd;
>  
>  	ret = bcmnand_ctrl_poll_status(ctrl, NAND_CTRL_RDY, NAND_CTRL_RDY, 0);

LGTM otherwise.

Thanks,
Miquèl