diff mbox series

[v5,2/3] kernel/resource: Refactor __request_region to allow external locking

Message ID 20210419070109.4780-2-apopple@nvidia.com (mailing list archive)
State New
Headers show
Series [v5,1/3] kernel/resource: Allow region_intersects users to hold resource_lock | expand

Commit Message

Alistair Popple April 19, 2021, 7:01 a.m. UTC
Refactor the portion of __request_region() done whilst holding the
resource_lock into a separate function to allow callers to hold the
lock.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 kernel/resource.c | 52 +++++++++++++++++++++++++++++------------------
 1 file changed, 32 insertions(+), 20 deletions(-)

Comments

David Hildenbrand April 20, 2021, 2:43 p.m. UTC | #1
On 19.04.21 09:01, Alistair Popple wrote:
> Refactor the portion of __request_region() done whilst holding the
> resource_lock into a separate function to allow callers to hold the
> lock.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>   kernel/resource.c | 52 +++++++++++++++++++++++++++++------------------
>   1 file changed, 32 insertions(+), 20 deletions(-)
> 
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 736768587d2d..75f8da722497 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -1181,31 +1181,16 @@ struct address_space *iomem_get_mapping(void)
>   	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;
>   
> @@ -1241,13 +1226,40 @@ struct resource * __request_region(struct resource *parent,
>   			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);

Reviewed-by: David Hildenbrand <david@redhat.com>
diff mbox series

Patch

diff --git a/kernel/resource.c b/kernel/resource.c
index 736768587d2d..75f8da722497 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1181,31 +1181,16 @@  struct address_space *iomem_get_mapping(void)
 	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;
 
@@ -1241,13 +1226,40 @@  struct resource * __request_region(struct resource *parent,
 			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;