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id B7F761F44957; Mon, 13 Dec 2021 09:28:41 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=collabora.com; s=mail; t=1639387722; bh=s/3YHODxTsyDf2kILZMedX/lcHccoNYLXp6/+n9Sn3c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=a5gtmajzup2dEW7fOaa5NxSgBLHYzOrhC1yCLvBWWgV6X+BTUmga4EoBwq1ZdXiUp ITBwu01QtwM6N4mZJIJgv28Kjl6pvFkl7rf01klHyk4ctcBfns/9kCw9zcqQVbEBio IBJr6KjpTbBtNpxofpBnJkgJnxZgK/z7FjhuSh2YNS/nmaTXTonmJmBGyHKVkJQor+ ITXRcYliyID9P0vIFvWPQeLWAlbrTPsLWzdd4P4MjAs45Bu58qHJ3WMRJm82wL3vHR Z+qto7WGDt1dnbR9OFpvl2P7Trf72vfbS7VRVeeBnVRmUdObKgDuZTPxFCKhrHBiZB APMWWI2YcEIOA== Date: Mon, 13 Dec 2021 10:28:01 +0100 From: Boris Brezillon To: Miquel Raynal Cc: Sean Nyekjaer , linux-kernel@vger.kernel.org, Marek Szyprowski , Richard Weinberger , Vignesh Raghavendra , Boris Brezillon , linux-mtd@lists.infradead.org Subject: Re: [PATCH v5 3/4] mtd: core: protect access to MTD devices while in suspend Message-ID: <20211213102801.569b50b1@collabora.com> In-Reply-To: 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ITBwu01QtwM6N4mZJIJgv28Kjl6pvFkl7rf01klHyk4ctcBfns/9kCw9zcqQVbEBio IBJr6KjpTbBtNpxofpBnJkgJnxZgK/z7FjhuSh2YNS/nmaTXTonmJmBGyHKVkJQor+ ITXRcYliyID9P0vIFvWPQeLWAlbrTPsLWzdd4P4MjAs45Bu58qHJ3WMRJm82wL3vHR Z+qto7WGDt1dnbR9OFpvl2P7Trf72vfbS7VRVeeBnVRmUdObKgDuZTPxFCKhrHBiZB APMWWI2YcEIOA== Date: Mon, 13 Dec 2021 10:28:01 +0100 From: Boris Brezillon To: Miquel Raynal Cc: Sean Nyekjaer , linux-kernel@vger.kernel.org, Marek Szyprowski , Richard Weinberger , Vignesh Raghavendra , Boris Brezillon , linux-mtd@lists.infradead.org Subject: Re: [PATCH v5 3/4] mtd: core: protect access to MTD devices while in suspend Message-ID: <20211213102801.569b50b1@collabora.com> In-Reply-To: <20211213101025.42c27b43@xps13> References: <20211129101908.6f1aa715@xps13> <20211129094129.xn364czofrgtvfb4@skn-laptop> <63be9121-18c3-1ef2-c448-f99fb861490f@samsung.com> <20211130124131.6pgu7enjgk6y536m@skn-laptop> <20211130141551.400331c8@collabora.com> <20211130132912.v6v45boce2zbnoy3@skn-laptop> <20211130143705.5d0404aa@collabora.com> <20211203143958.40645506@xps13> <20211209140721.6ki7gznvxwyn3cze@skn-laptop.hinnerup> <20211209152811.318bdf17@xps13> <20211210132535.gy7rqj5zblqlnz5y@skn-laptop.hadsten> <20211213101025.42c27b43@xps13> Organization: Collabora X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.30; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 13 Dec 2021 10:10:25 +0100 Miquel Raynal wrote: > Hi Sean, >=20 > sean@geanix.com wrote on Fri, 10 Dec 2021 14:25:35 +0100: >=20 > > On Thu, Dec 09, 2021 at 03:28:11PM +0100, Miquel Raynal wrote: =20 > > > Hi Sean, > > >=20 > > > sean@geanix.com wrote on Thu, 9 Dec 2021 15:07:21 +0100: > > > =20 > > > > On Fri, Dec 03, 2021 at 02:39:58PM +0100, Miquel Raynal wrote: =20 > > > > > Hello, > > > > > =20 > > > > > > > Fine by me, lets drop this series. =20 > > > > >=20 > > > > > FYI I've dropped the entire series from mtd/next. I'm waiting for= the > > > > > fix discussed below (without abusing the chip mutex ;-) ). =20 > > > >=20 > > > > Cool, looking forward to test a patch series :) =20 > > >=20 > > > Test? You mean "write"? :) > > >=20 > > > Cheers, > > > Miqu=C3=A8l =20 > >=20 > > Hi Miquel, > >=20 > > Should we us a atomic for the suspended variable? =20 >=20 > 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. >=20 > >=20 > > /Sean > >=20 > > diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/na= nd_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); > > =20 > > - return 0; > > + wait_event(chip->resume_wq, !chip->suspended); > > + } > > } > > =20 > > /** > > @@ -576,9 +579,7 @@ static int nand_block_markbad_lowlevel(struct nand_= chip *chip, loff_t ofs) > > nand_erase_nand(chip, &einfo, 0); > > =20 > > /* Write bad block marker to OOB */ > > - ret =3D nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > =20 > > ret =3D nand_markbad_bbm(chip, ofs); > > nand_release_device(chip); > > @@ -3759,9 +3760,7 @@ static int nand_read_oob(struct mtd_info *mtd, lo= ff_t from, > > ops->mode !=3D MTD_OPS_RAW) > > return -ENOTSUPP; > > =20 > > - ret =3D nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > =20 > > if (!ops->datbuf) > > ret =3D nand_do_read_oob(chip, from, ops); > > @@ -4352,9 +4351,7 @@ static int nand_write_oob(struct mtd_info *mtd, l= off_t to, > > =20 > > ops->retlen =3D 0; > > =20 > > - ret =3D nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > =20 > > switch (ops->mode) { > > case MTD_OPS_PLACE_OOB: > > @@ -4414,9 +4411,7 @@ int nand_erase_nand(struct nand_chip *chip, struc= t erase_info *instr, > > return -EIO; > > =20 > > /* Grab the lock and see if the device is available */ > > - ret =3D nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > =20 > > /* Shift to get first page */ > > page =3D (int)(instr->addr >> chip->page_shift); > > @@ -4503,7 +4498,7 @@ static void nand_sync(struct mtd_info *mtd) > > pr_debug("%s: called\n", __func__); > > =20 > > /* 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; > > =20 > > /* Select the NAND device */ > > - ret =3D nand_get_device(chip); > > - if (ret) > > - return ret; > > + nand_get_device(chip); > > =20 > > nand_select_target(chip, chipnr); > > =20 > > @@ -4593,6 +4586,8 @@ static void nand_resume(struct mtd_info *mtd) > > __func__); > > } > > mutex_unlock(&chip->lock); > > + > > + wake_up_all(&chip->resume_wq); > > } > > =20 > > /** > > @@ -5370,6 +5365,7 @@ static int nand_scan_ident(struct nand_chip *chip= , unsigned int maxchips, > > chip->cur_cs =3D -1; > > =20 > > mutex_init(&chip->lock); > > + init_waitqueue_head(&chip->resume_wq); > > =20 > > /* Enforce the right timings for reset/detection */ > > chip->current_interface_config =3D 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; =20 >=20 >=20 > Thanks, > Miqu=C3=A8l