linux-kernel - [RFC PATCH 2/6] resource: export find_next_iomem

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Message-Id: <20200729033424.2629-3-justin.he@arm.com>
Date:   Wed, 29 Jul 2020 11:34:20 +0800
From:   Jia He <justin.he@....com>
To:     Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Dave Jiang <dave.jiang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steve Capper <steve.capper@....com>,
        Mark Rutland <mark.rutland@....com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org,
        Wei Yang <richardw.yang@...ux.intel.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Ira Weiny <ira.weiny@...el.com>, Kaly Xin <Kaly.Xin@....com>,
        Jia He <justin.he@....com>
Subject: [RFC PATCH 2/6] resource: export find_next_iomem_res() helper

The helper is to find the lowest iomem resource that covers part of
[@start..@end]

It is useful when relaxing the alignment check for dax pmem kmem.

Signed-off-by: Jia He <justin.he@....com>
---
 include/linux/ioport.h | 3 +++
 kernel/resource.c      | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 6c2b06fe8beb..203fd16c9f45 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -247,6 +247,9 @@ extern struct resource * __request_region(struct resource *,
 
 extern void __release_region(struct resource *, resource_size_t,
 				resource_size_t);
+extern int find_next_iomem_res(resource_size_t start, resource_size_t end,
+			       unsigned long flags, unsigned long desc,
+			       bool first_lvl, struct resource *res);
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern int release_mem_region_adjustable(struct resource *, resource_size_t,
 				resource_size_t);
diff --git a/kernel/resource.c b/kernel/resource.c
index 841737bbda9e..57e6a6802a3d 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -338,7 +338,7 @@ EXPORT_SYMBOL(release_resource);
  * @first_lvl:	walk only the first level children, if set
  * @res:	return ptr, if resource found
  */
-static int find_next_iomem_res(resource_size_t start, resource_size_t end,
+int find_next_iomem_res(resource_size_t start, resource_size_t end,
 			       unsigned long flags, unsigned long desc,
 			       bool first_lvl, struct resource *res)
 {
@@ -391,6 +391,7 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
 	read_unlock(&resource_lock);
 	return p ? 0 : -ENODEV;
 }
+EXPORT_SYMBOL(find_next_iomem_res);
 
 static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
 				 unsigned long flags, unsigned long desc,
-- 
2.17.1