Subject: Re: [PATCH 2/3 v3] P4080/mtd: Only make elbc nand driver detect nand flash partitions

From: Anton Vorontsov <[email-masked]>
Date: Thu, 16 Sep 2010 12:21:41 +0400

On Thu, Sep 16, 2010 at 02:41:23PM +0800, Roy Zang wrote:
[...]
> -static int __devinit fsl_elbc_chip_probe(struct fsl_elbc_ctrl *ctrl,
> -                                      struct device_node *node)
> +/*
> + * Currently only one elbc probe is supported.
> + */
> +static int __devinit fsl_elbc_nand_probe(struct platform_device *dev)
>  {
> -     struct fsl_lbc_regs __iomem *lbc = ctrl->regs;
> +     struct fsl_lbc_regs __iomem *lbc;
>       struct fsl_elbc_mtd *priv;
>       struct resource res;
> +     struct fsl_elbc_fcm_ctrl *elbc_fcm_ctrl = NULL;
[...]
> -     ctrl->chips[bank] = priv;
> +     if (fsl_lbc_ctrl_dev->nand == NULL) {
> +             elbc_fcm_ctrl = kzalloc(sizeof(*elbc_fcm_ctrl), GFP_KERNEL);
> +             if (!elbc_fcm_ctrl) {
[...]
> +                     goto err;
> +             }
> +             fsl_lbc_ctrl_dev->nand = elbc_fcm_ctrl;
> +     }
> +
> +     elbc_fcm_ctrl->chips[bank] = priv;

Again, this will oops on the second probe. And you still don't
lock fsl_lbc_ctrl_dev->nand during check-then-assignment, so
with parallel probing there will be a race. :-(

We do have boards with several NAND chips (e.g.
arch/powerpc/boot/dts/mpc8610_hpcd.dts), so these issues
are all legitimate.

Thanks,

-- 
Anton Vorontsov
email: [email-masked]
irc://irc.freenode.net/bd2