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FAILED: patch "[PATCH] resource: fix locking in find_next_iomem_res()" failed to apply to 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jul 23, 2019 Stable branch

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The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 49f17c26c123b60fd1c74629eef077740d16ffc2 Mon Sep 17 00:00:00 2001
From: Nadav Amit <[email protected]>
Date: Thu, 18 Jul 2019 15:57:31 -0700
Subject: [PATCH] resource: fix locking in find_next_iomem_res()

Since resources can be removed, locking should ensure that the resource is not removed while accessing it. However, find_next_iomem_res() does not hold the lock while copying the data of the resource.

Keep holding the lock while the data is copied. While at it, change the return value to a more informative value. It is disregarded by the callers.

[[email protected]: fix find_next_iomem_res() documentation]
Link http://lkml.kernel.org/r/[email protected] open here
Fixes ff3cc952d3f00 ("resource: Add remove_resource interface")
Signed-off-by Nadav Amit <[email protected]>
Reviewed-by Andrew Morton <[email protected]>
Reviewed-by Dan Williams <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Toshi Kani <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Dave Hansen <[email protected]>
Cc Bjorn Helgaas <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
Signed-off-by Linus Torvalds <[email protected]>
kernel/resource.c +10 -10
index d22423e85cf8..3ced0cd45bdd 100644
@@ -326,7 +326,7 @@ EXPORT_SYMBOL(release_resource);
  *
  * If a resource is found, returns 0 and @*res is overwritten with the part
  * of the resource that's within [@start..@end]; if none is found, returns
- * -1 or -EINVAL for other invalid parameters.
+ * -ENODEV.  Returns -EINVAL for invalid parameters.
  *
  * This function walks the whole tree and not just first level children
  * unless @first_lvl is true.

@@ -365,16 +365,16 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
 			break;
 	}
 
+	if (p) {
+		/* copy data */
+		res->start = max(start, p->start);
+		res->end = min(end, p->end);
+		res->flags = p->flags;
+		res->desc = p->desc;
+	}
+
 	read_unlock(&resource_lock);
-	if (!p)
-		return -1;
-
-	/* copy data */
-	res->start = max(start, p->start);
-	res->end = min(end, p->end);
-	res->flags = p->flags;
-	res->desc = p->desc;
-	return 0;
+	return p ? 0 : -ENODEV;
 }
 
 static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,