lkml.org 
[lkml]   [2021]   [Oct]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 0/3] mtd: core: protect access to mtd devices while in suspend
On Tue, 19 Oct 2021 20:08:00 +0200
Sean Nyekjaer <sean@geanix.com> wrote:

> On Fri, Oct 15, 2021 at 08:22:06AM +0200, Miquel Raynal wrote:
> > Hi Sean,
> >
> > boris.brezillon@collabora.com wrote on Mon, 11 Oct 2021 16:05:46 +0200:
> >
> > > On Mon, 11 Oct 2021 13:52:50 +0200
>
> [ ... ]
>
> >
> > > > One (small) issue still present. gpmi_nand.c uses the rwsem before it's
> > > > initialized. Seems cumbersome to have every mtd/nand driver to call
> > > > init_waitqueue_head() and init_rwsem(). Could we somehow move the call
> > > > to mtd_set_dev_defaults() before nand_create_bbt()?
> > >
> > > I have a nasty trick for that one, but I'm not sure Miquel will like it
> > > (actually, I don't like it either, but it's so simple compared to the
> > > other options we have that I'm tempted to go for this approach until
> > > someone has time to invest in a cleaner solution :-)):
> > >
> > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> > > index 3d6c6e880520..a9ac2d528a4d 100644
> > > --- a/drivers/mtd/nand/raw/nand_base.c
> > > +++ b/drivers/mtd/nand/raw/nand_base.c
> > > @@ -6222,8 +6222,6 @@ static int nand_scan_tail(struct nand_chip *chip)
> > > mtd->_sync = nand_sync;
> > > mtd->_lock = nand_lock;
> > > mtd->_unlock = nand_unlock;
> > > - mtd->_suspend = nand_suspend;
> > > - mtd->_resume = nand_resume;
> > > mtd->_reboot = nand_shutdown;
> > > mtd->_block_isreserved = nand_block_isreserved;
> > > mtd->_block_isbad = nand_block_isbad;
> > > @@ -6269,6 +6267,13 @@ static int nand_scan_tail(struct nand_chip *chip)
> > > if (ret)
> > > goto err_free_secure_regions;
> > >
> > > + /*
> > > + * Populate the suspend/resume hooks after the BBT has been scanned to
> > > + * avoid using the suspend lock and resume waitqueue which are only
> > > + * initialized when mtd_device_register() is called.
> > > + */
> > > + mtd->_suspend = nand_suspend;
> > > + mtd->_resume = nand_resume;
> > > return 0;
> >
> > I'm fine with this as long as it is documented for now.
> >
>
> Hi Boris and Miquel,
>
> gpmi-nand.c sets NAND_SKIP_BBTSCAN so we won't get there and populate
> suspend resume hooks :(
> Guess there is other drivers that does the same thing...

This should fix the issue:

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 3d6c6e880520..c92b17f66994 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -6222,8 +6222,6 @@ static int nand_scan_tail(struct nand_chip *chip)
mtd->_sync = nand_sync;
mtd->_lock = nand_lock;
mtd->_unlock = nand_unlock;
- mtd->_suspend = nand_suspend;
- mtd->_resume = nand_resume;
mtd->_reboot = nand_shutdown;
mtd->_block_isreserved = nand_block_isreserved;
mtd->_block_isbad = nand_block_isbad;
@@ -6262,13 +6260,21 @@ static int nand_scan_tail(struct nand_chip *chip)

/* Check, if we should skip the bad block table scan */
if (chip->options & NAND_SKIP_BBTSCAN)
- return 0;
+ goto out;

/* Build bad block table */
ret = nand_create_bbt(chip);
if (ret)
goto err_free_secure_regions;

+out:
+ /*
+ * Populate the suspend/resume hooks after the BBT has been scanned to
+ * avoid using the suspend lock and resume waitqueue which are only
+ * initialized when mtd_device_register() is called.
+ */
+ mtd->_suspend = nand_suspend;
+ mtd->_resume = nand_resume;
return 0;

err_free_secure_regions:
\
 
 \ /
  Last update: 2021-10-20 08:53    [W:0.071 / U:18.796 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site