From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752436AbbKLAPz (ORCPT ); Wed, 11 Nov 2015 19:15:55 -0500 Received: from mail-pa0-f52.google.com ([209.85.220.52]:35219 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751671AbbKLAPx (ORCPT ); Wed, 11 Nov 2015 19:15:53 -0500 Date: Wed, 11 Nov 2015 16:15:50 -0800 From: Brian Norris To: Boris Brezillon Cc: David Woodhouse , linux-mtd@lists.infradead.org, Ezequiel Garcia , Marek Vasut , Scott Wood , Josh Wu , Robert Jarzmik , Kyungmin Park , Han Xu , Stefan Agner , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 13/11] mtd: assign mtd->dev.of_node when creating partition devices Message-ID: <20151112001550.GD96199@google.com> References: <1446262410-45754-1-git-send-email-computersforpeace@gmail.com> <1446424721-23471-1-git-send-email-boris.brezillon@free-electrons.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1446424721-23471-1-git-send-email-boris.brezillon@free-electrons.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 02, 2015 at 01:38:41AM +0100, Boris Brezillon wrote: > MTD partitions may have been created from a DT definition, and in this case > the ->of_node of the struct device embedded in mtd_info should point to > the DT node that was used to create the partition. > > Signed-off-by: Boris Brezillon I like the idea of this patch, but I'm not sure about all of its details. > --- > Hi Brian, > > Yet another patch that IMO should go into your "mtd: migrate 'of_node' > handling to core, not in mtd_part_parser_data" series. > > Best Regards, > > Boris > > drivers/mtd/mtdcore.c | 17 +++++++++++++---- > drivers/mtd/mtdpart.c | 3 +++ > drivers/mtd/ofpart.c | 1 + > include/linux/mtd/partitions.h | 1 + > 4 files changed, 18 insertions(+), 4 deletions(-) > > diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c > index b1eea48..6101288 100644 > --- a/drivers/mtd/mtdcore.c > +++ b/drivers/mtd/mtdcore.c > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -584,11 +585,13 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types, > const struct mtd_partition *parts, > int nr_parts) > { > - int ret; > + int ret, i; > struct mtd_partition *real_parts = NULL; > > ret = parse_mtd_partitions(mtd, types, &real_parts, parser_data); > - if (ret <= 0 && nr_parts && parts) { > + if (ret > 0) { > + nr_parts = ret; > + } else if (nr_parts && parts) { > real_parts = kmemdup(parts, sizeof(*parts) * nr_parts, > GFP_KERNEL); > if (!real_parts) > @@ -604,7 +607,7 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types, > ret = 0; > } > > - ret = mtd_add_device_partitions(mtd, real_parts, ret); > + ret = mtd_add_device_partitions(mtd, real_parts, nr_parts); > if (ret) > goto out; > > @@ -623,7 +626,13 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types, > } > > out: > - kfree(real_parts); > + if (real_parts) { > + for (i = 0; i < nr_parts; i++) > + of_node_put(real_parts[i].of_node); > + > + kfree(real_parts); > + } > + > return ret; > } > EXPORT_SYMBOL_GPL(mtd_device_parse_register); > diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c > index f8ba153..95f3a0d 100644 > --- a/drivers/mtd/mtdpart.c > +++ b/drivers/mtd/mtdpart.c > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -319,6 +320,7 @@ static int part_block_markbad(struct mtd_info *mtd, loff_t ofs) > > static inline void free_partition(struct mtd_part *p) > { > + of_node_put(mtd_get_of_node(&p->mtd)); > kfree(p->mtd.name); > kfree(p); > } > @@ -391,6 +393,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *master, > slave->mtd.dev.parent = IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) ? > &master->dev : > master->dev.parent; > + mtd_set_of_node(&slave->mtd, of_node_get(part->of_node)); > > slave->mtd._read = part_read; > slave->mtd._write = part_write; > diff --git a/drivers/mtd/ofpart.c b/drivers/mtd/ofpart.c > index f78d2ae..5c64e04 100644 > --- a/drivers/mtd/ofpart.c > +++ b/drivers/mtd/ofpart.c > @@ -111,6 +111,7 @@ static int parse_ofpart_partitions(struct mtd_info *master, > if (of_get_property(pp, "lock", &len)) > (*pparts)[i].mask_flags |= MTD_POWERUP_LOCK; > > + (*pparts)[i].of_node = of_node_get(pp); I don't think we should mix up too much of the error handling between ofpart.c and mtdcore.c (right now, you do of_node_get() here but the of_node_put() is forced into mtdcore.c). I think the problem here is the same as the problem with Linus' patch here: http://lists.infradead.org/pipermail/linux-mtd/2015-November/063219.html It's just too easy to leak resources when MTD parsers don't have their own cleanup functions (like C++ destructors, or the driver model's remove() function, or so many other resource models). If we had a cleanup function, then we could just put the release handling there. But actually, I don't think we need to 'get' the property here; we only need to 'get' it when we're putting it somewhere that will actually use it long term. i.e., when it actually gets assigned to the mtd.dev.of_node field and is headed for sysfs. IOW, I think we can grab the reference in add_mtd_device() and drop it in del_mtd_device(). This would handle both the partition and non-partition case the same. I have a patch to do that (for the non-partition case) queued up. I'll push it out soon, then I expect you can make this patch a lot simpler. Brian > i++; > } > > diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h > index 773975a..282644c 100644 > --- a/include/linux/mtd/partitions.h > +++ b/include/linux/mtd/partitions.h > @@ -42,6 +42,7 @@ struct mtd_partition { > uint64_t offset; /* offset within the master MTD space */ > uint32_t mask_flags; /* master MTD flags to mask out for this partition */ > struct nand_ecclayout *ecclayout; /* out of band layout for this partition (NAND only) */ > + struct device_node *of_node; /* OF node attached to the partition */ > }; > > #define MTDPART_OFS_RETAIN (-3) > -- > 2.1.4 >