Re: [3/3] mtd: cfi_cmdset_{0001, 0002}: use common MTD reboot boilerplate

[Guenter Roeck <linux@roeck-us.net>]

On Mon, Nov 02, 2015 at 01:58:18PM -0800, Brian Norris wrote:
> On Mon, Nov 02, 2015 at 12:05:13PM -0800, Guenter Roeck wrote:
> > On Thu, Dec 04, 2014 at 06:36:08PM -0800, Brian Norris wrote:
> > > We don't have to implement this glue code in the chip driver any more.
> > > 
> > > Signed-off-by: Brian Norris <computersforpeace@gmail.com>
> > > ---
> > > Not tested yet
> > > 
> > Tested-by: Guenter Roeck <linux@roeck-us.net>
> 
> Thanks! Did you verify that your reboot notifier callback (e.g.,
> cfi_intelext_reset()) is actually called on reboot?
> 
No, I just verified that it boots and shuts down correctly.

Do you want me to verify if the notifier is called, given the
problems you discovered with the patch ?

Thanks,
Guenter

> And actually, I do see a problem with this patch now, so I'm less likely
> to take it as-is; we never guarantee that this mtd_info struct actually
> gets registered via mtd_device_parse_register(), so even though we
> stick the right callback in mtd->_reboot(), we haven't actually ensured
> it will ever get called.
> 
> See, for instance, the calling path in (speaking of the devil)
> arch/cris/arch-v10/drivers/axisflashmap.c:
> 
> static struct mtd_info *flash_probe(void)
> {
> ...
> 	mtd_cse0 = probe_cs(&map_cse0);
> 	mtd_cse1 = probe_cs(&map_cse1);
> ...
>         if (mtd_cse0 && mtd_cse1) {
>                 struct mtd_info *mtds[] = { mtd_cse0, mtd_cse1 };
> 
> ...
>                 mtd_cse = mtd_concat_create(mtds, ARRAY_SIZE(mtds),
>                                             "cse0+cse1");
> 
> 
> So, either of map_cse0 or map_cse1 could be a CFI-based map, and so only the
> concatenation would be registered, and therefore the reboot() notifier will
> just be left assigned to the sub-device, but never registered with the core.
> 
> Now, it looks like this is one of very few cases that we'd have to worry
> about... right now I've only found physmap_of.c that does the same
> mtdconcat stuff. So maybe if we fixed mtdconcat, we could solve this...
> 
> MTD is too hairy :(
> 
> Anyway, I'll have to NAK my own patch still, and we should probalby go
> with your other solution to your current problems from here:
> 
> http://lists.infradead.org/pipermail/linux-mtd/2015-November/063022.html
> 
> Regards,
> Brian
> 
> > >  drivers/mtd/chips/cfi_cmdset_0001.c | 22 +++-------------------
> > >  drivers/mtd/chips/cfi_cmdset_0002.c | 22 +++-------------------
> > >  2 files changed, 6 insertions(+), 38 deletions(-)
> > > 
> > > diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
> > > index 286b97a304cf..3df9744496b2 100644
> > > --- a/drivers/mtd/chips/cfi_cmdset_0001.c
> > > +++ b/drivers/mtd/chips/cfi_cmdset_0001.c
> > > @@ -28,7 +28,6 @@
> > >  #include <linux/slab.h>
> > >  #include <linux/delay.h>
> > >  #include <linux/interrupt.h>
> > > -#include <linux/reboot.h>
> > >  #include <linux/bitmap.h>
> > >  #include <linux/mtd/xip.h>
> > >  #include <linux/mtd/map.h>
> > > @@ -80,7 +79,7 @@ static int cfi_intelext_get_user_prot_info(struct mtd_info *, size_t,
> > >  #endif
> > >  static int cfi_intelext_suspend (struct mtd_info *);
> > >  static void cfi_intelext_resume (struct mtd_info *);
> > > -static int cfi_intelext_reboot (struct notifier_block *, unsigned long, void *);
> > > +static void cfi_intelext_reset(struct mtd_info *);
> > >  
> > >  static void cfi_intelext_destroy(struct mtd_info *);
> > >  
> > > @@ -486,13 +485,12 @@ struct mtd_info *cfi_cmdset_0001(struct map_info *map, int primary)
> > >  	mtd->_is_locked = cfi_intelext_is_locked;
> > >  	mtd->_suspend = cfi_intelext_suspend;
> > >  	mtd->_resume  = cfi_intelext_resume;
> > > +	mtd->_reboot  = cfi_intelext_reset;
> > >  	mtd->flags   = MTD_CAP_NORFLASH;
> > >  	mtd->name    = map->name;
> > >  	mtd->writesize = 1;
> > >  	mtd->writebufsize = cfi_interleave(cfi) << cfi->cfiq->MaxBufWriteSize;
> > >  
> > > -	mtd->reboot_notifier.notifier_call = cfi_intelext_reboot;
> > > -
> > >  	if (cfi->cfi_mode == CFI_MODE_CFI) {
> > >  		/*
> > >  		 * It's a real CFI chip, not one for which the probe
> > > @@ -646,7 +644,6 @@ static struct mtd_info *cfi_intelext_setup(struct mtd_info *mtd)
> > >  		goto setup_err;
> > >  
> > >  	__module_get(THIS_MODULE);
> > > -	register_reboot_notifier(&mtd->reboot_notifier);
> > >  	return mtd;
> > >  
> > >   setup_err:
> > > @@ -2605,7 +2602,7 @@ static void cfi_intelext_resume(struct mtd_info *mtd)
> > >  		cfi_intelext_restore_locks(mtd);
> > >  }
> > >  
> > > -static int cfi_intelext_reset(struct mtd_info *mtd)
> > > +static void cfi_intelext_reset(struct mtd_info *mtd)
> > >  {
> > >  	struct map_info *map = mtd->priv;
> > >  	struct cfi_private *cfi = map->fldrv_priv;
> > > @@ -2626,18 +2623,6 @@ static int cfi_intelext_reset(struct mtd_info *mtd)
> > >  		}
> > >  		mutex_unlock(&chip->mutex);
> > >  	}
> > > -
> > > -	return 0;
> > > -}
> > > -
> > > -static int cfi_intelext_reboot(struct notifier_block *nb, unsigned long val,
> > > -			       void *v)
> > > -{
> > > -	struct mtd_info *mtd;
> > > -
> > > -	mtd = container_of(nb, struct mtd_info, reboot_notifier);
> > > -	cfi_intelext_reset(mtd);
> > > -	return NOTIFY_DONE;
> > >  }
> > >  
> > >  static void cfi_intelext_destroy(struct mtd_info *mtd)
> > > @@ -2647,7 +2632,6 @@ static void cfi_intelext_destroy(struct mtd_info *mtd)
> > >  	struct mtd_erase_region_info *region;
> > >  	int i;
> > >  	cfi_intelext_reset(mtd);
> > > -	unregister_reboot_notifier(&mtd->reboot_notifier);
> > >  	kfree(cfi->cmdset_priv);
> > >  	kfree(cfi->cfiq);
> > >  	kfree(cfi->chips[0].priv);
> > > diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
> > > index c50d8cf0f60d..c4f63482cf96 100644
> > > --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> > > +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> > > @@ -31,7 +31,6 @@
> > >  #include <linux/slab.h>
> > >  #include <linux/delay.h>
> > >  #include <linux/interrupt.h>
> > > -#include <linux/reboot.h>
> > >  #include <linux/of.h>
> > >  #include <linux/of_platform.h>
> > >  #include <linux/mtd/map.h>
> > > @@ -57,7 +56,7 @@ static int cfi_amdstd_erase_varsize(struct mtd_info *, struct erase_info *);
> > >  static void cfi_amdstd_sync (struct mtd_info *);
> > >  static int cfi_amdstd_suspend (struct mtd_info *);
> > >  static void cfi_amdstd_resume (struct mtd_info *);
> > > -static int cfi_amdstd_reboot(struct notifier_block *, unsigned long, void *);
> > > +static void cfi_amdstd_reset(struct mtd_info *);
> > >  static int cfi_amdstd_get_fact_prot_info(struct mtd_info *, size_t,
> > >  					 size_t *, struct otp_info *);
> > >  static int cfi_amdstd_get_user_prot_info(struct mtd_info *, size_t,
> > > @@ -529,6 +528,7 @@ struct mtd_info *cfi_cmdset_0002(struct map_info *map, int primary)
> > >  	mtd->_sync    = cfi_amdstd_sync;
> > >  	mtd->_suspend = cfi_amdstd_suspend;
> > >  	mtd->_resume  = cfi_amdstd_resume;
> > > +	mtd->_reboot  = cfi_amdstd_reset;
> > >  	mtd->_read_user_prot_reg = cfi_amdstd_read_user_prot_reg;
> > >  	mtd->_read_fact_prot_reg = cfi_amdstd_read_fact_prot_reg;
> > >  	mtd->_get_fact_prot_info = cfi_amdstd_get_fact_prot_info;
> > > @@ -544,7 +544,6 @@ struct mtd_info *cfi_cmdset_0002(struct map_info *map, int primary)
> > >  			mtd->writebufsize);
> > >  
> > >  	mtd->_panic_write = cfi_amdstd_panic_write;
> > > -	mtd->reboot_notifier.notifier_call = cfi_amdstd_reboot;
> > >  
> > >  	if (cfi->cfi_mode==CFI_MODE_CFI){
> > >  		unsigned char bootloc;
> > > @@ -717,7 +716,6 @@ static struct mtd_info *cfi_amdstd_setup(struct mtd_info *mtd)
> > >  	}
> > >  
> > >  	__module_get(THIS_MODULE);
> > > -	register_reboot_notifier(&mtd->reboot_notifier);
> > >  	return mtd;
> > >  
> > >   setup_err:
> > > @@ -2871,7 +2869,7 @@ static void cfi_amdstd_resume(struct mtd_info *mtd)
> > >   * the flash is in query/program/erase mode will prevent the CPU from
> > >   * fetching the bootloader code, requiring a hard reset or power cycle.
> > >   */
> > > -static int cfi_amdstd_reset(struct mtd_info *mtd)
> > > +static void cfi_amdstd_reset(struct mtd_info *mtd)
> > >  {
> > >  	struct map_info *map = mtd->priv;
> > >  	struct cfi_private *cfi = map->fldrv_priv;
> > > @@ -2893,19 +2891,6 @@ static int cfi_amdstd_reset(struct mtd_info *mtd)
> > >  
> > >  		mutex_unlock(&chip->mutex);
> > >  	}
> > > -
> > > -	return 0;
> > > -}
> > > -
> > > -
> > > -static int cfi_amdstd_reboot(struct notifier_block *nb, unsigned long val,
> > > -			       void *v)
> > > -{
> > > -	struct mtd_info *mtd;
> > > -
> > > -	mtd = container_of(nb, struct mtd_info, reboot_notifier);
> > > -	cfi_amdstd_reset(mtd);
> > > -	return NOTIFY_DONE;
> > >  }
> > >  
> > >  
> > > @@ -2915,7 +2900,6 @@ static void cfi_amdstd_destroy(struct mtd_info *mtd)
> > >  	struct cfi_private *cfi = map->fldrv_priv;
> > >  
> > >  	cfi_amdstd_reset(mtd);
> > > -	unregister_reboot_notifier(&mtd->reboot_notifier);
> > >  	kfree(cfi->cmdset_priv);
> > >  	kfree(cfi->cfiq);
> > >  	kfree(cfi);