Messages in this thread | | | Date | Wed, 20 Oct 2021 09:12:28 +0200 | From | Miquel Raynal <> | Subject | Re: [PATCH 0/3] mtd: core: protect access to mtd devices while in suspend |
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Hi Boris,
boris.brezillon@collabora.com wrote on Wed, 20 Oct 2021 09:00:58 +0200:
> On Wed, 20 Oct 2021 08:52:50 +0200 > Boris Brezillon <boris.brezillon@collabora.com> wrote: > > > 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: > > Actually, this version is even cleaner: > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > index 3d6c6e880520..98c39b7f6279 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; > @@ -6261,14 +6259,20 @@ static int nand_scan_tail(struct nand_chip *chip) > goto err_free_interface_config; > > /* Check, if we should skip the bad block table scan */ > - if (chip->options & NAND_SKIP_BBTSCAN) > - return 0; > - > - /* Build bad block table */ > - ret = nand_create_bbt(chip); > - if (ret) > - goto err_free_secure_regions; > + if (chip->options & NAND_SKIP_BBTSCAN) { > + /* Build bad block table */ > + ret = nand_create_bbt(chip); > + if (ret) > + goto err_free_secure_regions; > + }
Nice idea.
> > + /* > + * 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:
Cheers, Miquèl
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