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

[Zang Roy-R61911]

> -----Original Message-----
> From: Anton Vorontsov [mailto:cbouatmailru at gmail.com]
> Sent: Thursday, September 16, 2010 16:22 PM
> To: Zang Roy-R61911
> Cc: linux-mtd at lists.infradead.org; dwmw2 at infradead.org; dedekind1 at gmail.com;
> akpm at linux-foundation.org; Lan Chunhe-B25806; Wood Scott-B07421; Gala Kumar-
> B11780; linuxppc-dev at ozlabs.org
> Subject: Re: [PATCH 2/3 v3] P4080/mtd: Only make elbc nand driver detect nand
> flash partitions
> 
> 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.
Why?

> 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.
OK. I can add a mutex here.
Thanks.
Roy