| Message ID | 1446424721-23471-1-git-send-email-boris.brezillon@free-electrons.com |
|---|---|
| State | Changes Requested |
| Headers | show |
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 <boris.brezillon@free-electrons.com> 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 <linux/err.h> > #include <linux/ioctl.h> > #include <linux/init.h> > +#include <linux/of.h> > #include <linux/proc_fs.h> > #include <linux/idr.h> > #include <linux/backing-dev.h> > @@ -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 <linux/kmod.h> > #include <linux/mtd/mtd.h> > #include <linux/mtd/partitions.h> > +#include <linux/of.h> > #include <linux/err.h> > #include <linux/kconfig.h> > > @@ -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 >
Hi Brian, On Wed, 11 Nov 2015 16:15:50 -0800 Brian Norris <computersforpeace@gmail.com> wrote: > 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 <boris.brezillon@free-electrons.com> > > 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 <linux/err.h> > > #include <linux/ioctl.h> > > #include <linux/init.h> > > +#include <linux/of.h> > > #include <linux/proc_fs.h> > > #include <linux/idr.h> > > #include <linux/backing-dev.h> > > @@ -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 <linux/kmod.h> > > #include <linux/mtd/mtd.h> > > #include <linux/mtd/partitions.h> > > +#include <linux/of.h> > > #include <linux/err.h> > > #include <linux/kconfig.h> > > > > @@ -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. Hm, actually I think we need it. When you iterate over child nodes with for_each_child_of_node(), the node is released (of_node_put() is called) after each iteration. While this is not a problem for mtd device registration (because the controller usually retain the reference when add_mtd_device() is called), this is not true for the partitions. And if the partitions are ever defined using an overlay, this can be a problem. To sum-up, I think we should retain the node reference until add_mtd_device() has retained it, so maybe we should have a ->cleanup() function in mtd part parsers. Best Regards, Boris
On Thu, Nov 12, 2015 at 02:22:20PM +0100, Boris Brezillon wrote: > On Wed, 11 Nov 2015 16:15:50 -0800 > Brian Norris <computersforpeace@gmail.com> wrote: > > 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. > > Hm, actually I think we need it. When you iterate over child nodes with > for_each_child_of_node(), the node is released (of_node_put() is > called) after each iteration. While this is not a problem for mtd > device registration (because the controller usually retain the > reference when add_mtd_device() is called), this is not true for the > partitions. And if the partitions are ever defined using an overlay, > this can be a problem. Yep. > To sum-up, I think we should retain the node reference until > add_mtd_device() has retained it, so maybe we should have a ->cleanup() > function in mtd part parsers. OK. I'll drop my patch and send out my ->cleanup() stuff instead, so you can patch on top of that. Brian
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 <linux/err.h> #include <linux/ioctl.h> #include <linux/init.h> +#include <linux/of.h> #include <linux/proc_fs.h> #include <linux/idr.h> #include <linux/backing-dev.h> @@ -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 <linux/kmod.h> #include <linux/mtd/mtd.h> #include <linux/mtd/partitions.h> +#include <linux/of.h> #include <linux/err.h> #include <linux/kconfig.h> @@ -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++; } 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)
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 <boris.brezillon@free-electrons.com> --- 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(-)