[06/25] mm: factor out a devm_request_free_mem_region helper

Submitted by Christoph Hellwig on June 17, 2019, 12:27 p.m.

Details

Message ID 20190617122733.22432-7-hch@lst.de
State New
Headers show
Series "dev_pagemap related cleanups v2" ( rev: 2 1 ) in Nouveau

Not browsing as part of any series.

Commit Message

Christoph Hellwig June 17, 2019, 12:27 p.m.
Keep the physical address allocation that hmm_add_device does with the
rest of the resource code, and allow future reuse of it without the hmm
wrapper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
---
 include/linux/ioport.h |  2 ++
 kernel/resource.c      | 39 +++++++++++++++++++++++++++++++++++++++
 mm/hmm.c               | 33 ++++-----------------------------
 3 files changed, 45 insertions(+), 29 deletions(-)

Patch hide | download patch | download mbox

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index da0ebaec25f0..76a33ae3bf6c 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -286,6 +286,8 @@  static inline bool resource_overlaps(struct resource *r1, struct resource *r2)
        return (r1->start <= r2->end && r1->end >= r2->start);
 }
 
+struct resource *devm_request_free_mem_region(struct device *dev,
+		struct resource *base, unsigned long size);
 
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */
diff --git a/kernel/resource.c b/kernel/resource.c
index 158f04ec1d4f..d22423e85cf8 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1628,6 +1628,45 @@  void resource_list_free(struct list_head *head)
 }
 EXPORT_SYMBOL(resource_list_free);
 
+#ifdef CONFIG_DEVICE_PRIVATE
+/**
+ * devm_request_free_mem_region - find free region for device private memory
+ *
+ * @dev: device struct to bind the resource to
+ * @size: size in bytes of the device memory to add
+ * @base: resource tree to look in
+ *
+ * This function tries to find an empty range of physical address big enough to
+ * contain the new resource, so that it can later be hotplugged as ZONE_DEVICE
+ * memory, which in turn allocates struct pages.
+ */
+struct resource *devm_request_free_mem_region(struct device *dev,
+		struct resource *base, unsigned long size)
+{
+	resource_size_t end, addr;
+	struct resource *res;
+
+	size = ALIGN(size, 1UL << PA_SECTION_SHIFT);
+	end = min_t(unsigned long, base->end, (1UL << MAX_PHYSMEM_BITS) - 1);
+	addr = end - size + 1UL;
+
+	for (; addr > size && addr >= base->start; addr -= size) {
+		if (region_intersects(addr, size, 0, IORES_DESC_NONE) !=
+				REGION_DISJOINT)
+			continue;
+
+		res = devm_request_mem_region(dev, addr, size, dev_name(dev));
+		if (!res)
+			return ERR_PTR(-ENOMEM);
+		res->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
+		return res;
+	}
+
+	return ERR_PTR(-ERANGE);
+}
+EXPORT_SYMBOL_GPL(devm_request_free_mem_region);
+#endif /* CONFIG_DEVICE_PRIVATE */
+
 static int __init strict_iomem(char *str)
 {
 	if (strstr(str, "relaxed"))
diff --git a/mm/hmm.c b/mm/hmm.c
index 64e788bb1211..172d695dcb8b 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -25,8 +25,6 @@ 
 #include <linux/mmu_notifier.h>
 #include <linux/memory_hotplug.h>
 
-#define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT)
-
 #if IS_ENABLED(CONFIG_HMM_MIRROR)
 static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
 
@@ -1405,7 +1403,6 @@  struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
 				  unsigned long size)
 {
 	struct hmm_devmem *devmem;
-	resource_size_t addr;
 	void *result;
 	int ret;
 
@@ -1427,32 +1424,10 @@  struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
 	if (ret)
 		return ERR_PTR(ret);
 
-	size = ALIGN(size, PA_SECTION_SIZE);
-	addr = min((unsigned long)iomem_resource.end,
-		   (1UL << MAX_PHYSMEM_BITS) - 1);
-	addr = addr - size + 1UL;
-
-	/*
-	 * FIXME add a new helper to quickly walk resource tree and find free
-	 * range
-	 *
-	 * FIXME what about ioport_resource resource ?
-	 */
-	for (; addr > size && addr >= iomem_resource.start; addr -= size) {
-		ret = region_intersects(addr, size, 0, IORES_DESC_NONE);
-		if (ret != REGION_DISJOINT)
-			continue;
-
-		devmem->resource = devm_request_mem_region(device, addr, size,
-							   dev_name(device));
-		if (!devmem->resource)
-			return ERR_PTR(-ENOMEM);
-		break;
-	}
-	if (!devmem->resource)
-		return ERR_PTR(-ERANGE);
-
-	devmem->resource->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
+	devmem->resource = devm_request_free_mem_region(device, &iomem_resource,
+			size);
+	if (IS_ERR(devmem->resource))
+		return ERR_CAST(devmem->resource);
 	devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
 	devmem->pfn_last = devmem->pfn_first +
 			   (resource_size(devmem->resource) >> PAGE_SHIFT);

Comments

On Mon, Jun 17, 2019 at 5:27 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Keep the physical address allocation that hmm_add_device does with the
> rest of the resource code, and allow future reuse of it without the hmm
> wrapper.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> ---
>  include/linux/ioport.h |  2 ++
>  kernel/resource.c      | 39 +++++++++++++++++++++++++++++++++++++++
>  mm/hmm.c               | 33 ++++-----------------------------
>  3 files changed, 45 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index da0ebaec25f0..76a33ae3bf6c 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -286,6 +286,8 @@ static inline bool resource_overlaps(struct resource *r1, struct resource *r2)
>         return (r1->start <= r2->end && r1->end >= r2->start);
>  }
>
> +struct resource *devm_request_free_mem_region(struct device *dev,
> +               struct resource *base, unsigned long size);

This appears to need a 'static inline' helper stub in the
CONFIG_DEVICE_PRIVATE=n case, otherwise this compile error triggers:

ld: mm/hmm.o: in function `hmm_devmem_add':
/home/dwillia2/git/linux/mm/hmm.c:1427: undefined reference to
`devm_request_free_mem_region'
On Mon, Jun 17, 2019 at 10:37:12AM -0700, Dan Williams wrote:
> > +struct resource *devm_request_free_mem_region(struct device *dev,
> > +               struct resource *base, unsigned long size);
> 
> This appears to need a 'static inline' helper stub in the
> CONFIG_DEVICE_PRIVATE=n case, otherwise this compile error triggers:
> 
> ld: mm/hmm.o: in function `hmm_devmem_add':
> /home/dwillia2/git/linux/mm/hmm.c:1427: undefined reference to
> `devm_request_free_mem_region'

*sigh* - hmm_devmem_add already only works for device private memory,
so it shouldn't be built if that option is not enabled, but in the
current code it is.  And a few patches later in the series we just
kill it off entirely, and the only real caller of this function
already depends on CONFIG_DEVICE_PRIVATE.  So I'm tempted to just
ignore the strict bisectability requirement here instead of making
things messy by either adding the proper ifdefs in hmm.c or providing
a stub we don't really need.
On Mon, Jun 17, 2019 at 07:40:18PM +0200, Christoph Hellwig wrote:
> On Mon, Jun 17, 2019 at 10:37:12AM -0700, Dan Williams wrote:
> > > +struct resource *devm_request_free_mem_region(struct device *dev,
> > > +               struct resource *base, unsigned long size);
> > 
> > This appears to need a 'static inline' helper stub in the
> > CONFIG_DEVICE_PRIVATE=n case, otherwise this compile error triggers:
> > 
> > ld: mm/hmm.o: in function `hmm_devmem_add':
> > /home/dwillia2/git/linux/mm/hmm.c:1427: undefined reference to
> > `devm_request_free_mem_region'
> 
> *sigh* - hmm_devmem_add already only works for device private memory,
> so it shouldn't be built if that option is not enabled, but in the
> current code it is.  And a few patches later in the series we just
> kill it off entirely, and the only real caller of this function
> already depends on CONFIG_DEVICE_PRIVATE.  So I'm tempted to just
> ignore the strict bisectability requirement here instead of making
> things messy by either adding the proper ifdefs in hmm.c or providing
> a stub we don't really need.

Actually, I could just move the patch to mark CONFIG_DEVICE_PUBLIC
broken earlier, which would force hmm_devmem_add to only be built
when CONFIG_DEVICE_PRIVATE ist set.