The patch titled
Subject: kernel/resource: refactor __request_region to allow external locking
has been added to the -mm tree. Its filename is
kernel-resource-refactor-__request_region-to-allow-external-locking.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kernel-resource-refactor-__request_region-to-allow-external-locking.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kernel-resource-refactor-__request_region-to-allow-external-locking.patch
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------------------------------------------------------
From: Alistair Popple <apopple@xxxxxxxxxx>
Subject: kernel/resource: refactor __request_region to allow external locking
Refactor the portion of __request_region() done whilst holding the
resource_lock into a separate function to allow callers to hold the lock.
Link: https://lkml.kernel.org/r/20210419070109.4780-2-apopple@xxxxxxxxxx
Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Muchun Song <smuchun@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/resource.c | 52 +++++++++++++++++++++++++++-----------------
1 file changed, 32 insertions(+), 20 deletions(-)
--- a/kernel/resource.c~kernel-resource-refactor-__request_region-to-allow-external-locking
+++ a/kernel/resource.c
@@ -1160,31 +1160,16 @@ struct address_space *iomem_get_mapping(
return smp_load_acquire(&iomem_inode)->i_mapping;
}
-/**
- * __request_region - create a new busy resource region
- * @parent: parent resource descriptor
- * @start: resource start address
- * @n: resource region size
- * @name: reserving caller's ID string
- * @flags: IO resource flags
- */
-struct resource * __request_region(struct resource *parent,
+static int __request_region_locked(struct resource *res, struct resource *parent,
resource_size_t start, resource_size_t n,
const char *name, int flags)
{
DECLARE_WAITQUEUE(wait, current);
- struct resource *res = alloc_resource(GFP_KERNEL);
- struct resource *orig_parent = parent;
-
- if (!res)
- return NULL;
res->name = name;
res->start = start;
res->end = start + n - 1;
- write_lock(&resource_lock);
-
for (;;) {
struct resource *conflict;
@@ -1220,13 +1205,40 @@ struct resource * __request_region(struc
continue;
}
/* Uhhuh, that didn't work out.. */
- free_resource(res);
- res = NULL;
- break;
+ return -EBUSY;
}
+
+ return 0;
+}
+
+/**
+ * __request_region - create a new busy resource region
+ * @parent: parent resource descriptor
+ * @start: resource start address
+ * @n: resource region size
+ * @name: reserving caller's ID string
+ * @flags: IO resource flags
+ */
+struct resource *__request_region(struct resource *parent,
+ resource_size_t start, resource_size_t n,
+ const char *name, int flags)
+{
+ struct resource *res = alloc_resource(GFP_KERNEL);
+ int ret;
+
+ if (!res)
+ return NULL;
+
+ write_lock(&resource_lock);
+ ret = __request_region_locked(res, parent, start, n, name, flags);
write_unlock(&resource_lock);
- if (res && orig_parent == &iomem_resource)
+ if (ret) {
+ free_resource(res);
+ return NULL;
+ }
+
+ if (parent == &iomem_resource)
revoke_iomem(res);
return res;
_
Patches currently in -mm which might be from apopple@xxxxxxxxxx are
kernel-resource-allow-region_intersects-users-to-hold-resource_lock.patch
kernel-resource-refactor-__request_region-to-allow-external-locking.patch
kernel-resource-fix-locking-in-request_free_mem_region.patch
