Messages in this thread | | | Date | Mon, 13 Dec 2021 10:28:01 +0100 | From | Boris Brezillon <> | Subject | Re: [PATCH v5 3/4] mtd: core: protect access to MTD devices while in suspend |
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On Mon, 13 Dec 2021 10:10:25 +0100 Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> Hi Sean, > > sean@geanix.com wrote on Fri, 10 Dec 2021 14:25:35 +0100: > > > On Thu, Dec 09, 2021 at 03:28:11PM +0100, Miquel Raynal wrote: > > > Hi Sean, > > > > > > sean@geanix.com wrote on Thu, 9 Dec 2021 15:07:21 +0100: > > > > > > > On Fri, Dec 03, 2021 at 02:39:58PM +0100, Miquel Raynal wrote: > > > > > Hello, > > > > > > > > > > > > Fine by me, lets drop this series. > > > > > > > > > > FYI I've dropped the entire series from mtd/next. I'm waiting for the > > > > > fix discussed below (without abusing the chip mutex ;-) ). > > > > > > > > Cool, looking forward to test a patch series :) > > > > > > Test? You mean "write"? :) > > > > > > Cheers, > > > Miquèl > > > > Hi Miquel, > > > > Should we us a atomic for the suspended variable? > > I haven't thought about it extensively, an atomic variable sound fine > but I am definitely not a locking expert...
No need to use an atomic if the variable is already protected by a lock when accessed, and this seems to be case.
> > > > > /Sean > > > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c > > index b3a9bc08b4bb..eb4ec9a42d49 100644 > > --- a/drivers/mtd/nand/raw/nand_base.c > > +++ b/drivers/mtd/nand/raw/nand_base.c > > @@ -338,16 +338,19 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs) > > * > > * Return: -EBUSY if the chip has been suspended, 0 otherwise
You need to fix the documentation and make it clear that the caller will be blocked if the chip is suspended.
> > */ > > -static int nand_get_device(struct nand_chip *chip) > > +static void nand_get_device(struct nand_chip *chip) > > { > > - mutex_lock(&chip->lock); > > - if (chip->suspended) { > > + /* Wait until the device is resumed. */ > > + while (1) { > > + mutex_lock(&chip->lock); > > + if (!chip->suspended) { > > + mutex_lock(&chip->controller->lock); > > + return; > > + } > > mutex_unlock(&chip->lock); > > - return -EBUSY; > > - } > > - mutex_lock(&chip->controller->lock); > > > > - return 0; > > + wait_event(chip->resume_wq, !chip->suspended); > > + } > > } > > > > /** > > @@ -576,9 +579,7 @@ static int nand_block_markbad_lowlevel(struct nand_chip *chip, loff_t ofs) > > nand_erase_nand(chip, &einfo, 0); > > > > /* Write bad block marker to OOB */ > > - ret = nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > > > ret = nand_markbad_bbm(chip, ofs); > > nand_release_device(chip); > > @@ -3759,9 +3760,7 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from, > > ops->mode != MTD_OPS_RAW) > > return -ENOTSUPP; > > > > - ret = nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > > > if (!ops->datbuf) > > ret = nand_do_read_oob(chip, from, ops); > > @@ -4352,9 +4351,7 @@ static int nand_write_oob(struct mtd_info *mtd, loff_t to, > > > > ops->retlen = 0; > > > > - ret = nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > > > switch (ops->mode) { > > case MTD_OPS_PLACE_OOB: > > @@ -4414,9 +4411,7 @@ int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr, > > return -EIO; > > > > /* Grab the lock and see if the device is available */ > > - ret = nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > > > /* Shift to get first page */ > > page = (int)(instr->addr >> chip->page_shift); > > @@ -4503,7 +4498,7 @@ static void nand_sync(struct mtd_info *mtd) > > pr_debug("%s: called\n", __func__); > > > > /* Grab the lock and see if the device is available */ > > - WARN_ON(nand_get_device(chip)); > > + nand_get_device(chip); > > /* Release it and go back */ > > nand_release_device(chip); > > } > > @@ -4520,9 +4515,7 @@ static int nand_block_isbad(struct mtd_info *mtd, loff_t offs) > > int ret; > > > > /* Select the NAND device */ > > - ret = nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > > > nand_select_target(chip, chipnr); > > > > @@ -4593,6 +4586,8 @@ static void nand_resume(struct mtd_info *mtd) > > __func__); > > } > > mutex_unlock(&chip->lock); > > + > > + wake_up_all(&chip->resume_wq); > > } > > > > /** > > @@ -5370,6 +5365,7 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips, > > chip->cur_cs = -1; > > > > mutex_init(&chip->lock); > > + init_waitqueue_head(&chip->resume_wq); > > > > /* Enforce the right timings for reset/detection */ > > chip->current_interface_config = nand_get_reset_interface_config(); > > diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h > > index b2f9dd3cbd69..248054560581 100644 > > --- a/include/linux/mtd/rawnand.h > > +++ b/include/linux/mtd/rawnand.h > > @@ -1294,6 +1294,7 @@ struct nand_chip { > > /* Internals */ > > struct mutex lock; > > unsigned int suspended : 1; > > + wait_queue_head_t resume_wq; > > int cur_cs; > > int read_retries; > > struct nand_secure_region *secure_regions; > > > Thanks, > Miquèl
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