From: Alistair Popple <apopple@nvidia.com>
To: <akpm@linux-foundation.org>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<david@redhat.com>, <daniel.vetter@ffwll.ch>,
<dan.j.williams@intel.com>, <gregkh@linuxfoundation.org>,
<jhubbard@nvidia.com>, <jglisse@redhat.com>,
<bsingharora@gmail.com>, <smuchun@gmail.com>,
Alistair Popple <apopple@nvidia.com>
Subject: [PATCH v5 2/3] kernel/resource: Refactor __request_region to allow external locking
Date: Mon, 19 Apr 2021 17:01:08 +1000 [thread overview]
Message-ID: <20210419070109.4780-2-apopple@nvidia.com> (raw)
In-Reply-To: <20210419070109.4780-1-apopple@nvidia.com>
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);
return res;
--
2.20.1
next prev parent reply other threads:[~2021-04-19 7:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-19 7:01 [PATCH v5 1/3] kernel/resource: Allow region_intersects users to hold resource_lock Alistair Popple
2021-04-19 7:01 ` Alistair Popple [this message]
2021-04-20 14:43 ` [PATCH v5 2/3] kernel/resource: Refactor __request_region to allow external locking David Hildenbrand
2021-04-19 7:01 ` [PATCH v5 3/3] kernel/resource: Fix locking in request_free_mem_region Alistair Popple
2021-04-20 14:48 ` David Hildenbrand
2021-04-19 14:18 ` [PATCH v5 1/3] kernel/resource: Allow region_intersects users to hold resource_lock David Hildenbrand
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