Commit 49f17c26 authored Jul 18, 2019 by Nadav Amit Committed by Linus Torvalds Jul 18, 2019

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.

[akpm@linux-foundation.org: fix find_next_iomem_res() documentation]
Link: http://lkml.kernel.org/r/20190613045903.4922-2-namit@vmware.com


Fixes: ff3cc952 ("resource: Add remove_resource interface")
Signed-off-by: Nadav Amit <namit@vmware.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent c0630669

kernel/resource.c

+10 −10

Original line number	Diff line number	Diff line
		@@ -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;
		}

		read_unlock(&resource_lock);
		if (!p)
		return -1;

		if (p) {
		/* copy data */
		res->start = max(start, p->start);
		res->end = min(end, p->end);
		res->flags = p->flags;
		res->desc = p->desc;
		return 0;
		}

		read_unlock(&resource_lock);
		return p ? 0 : -ENODEV;
		}

		static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,

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