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resource: fix locking in find_next_iomem_res()

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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: ff3cc952d3f00 ("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>
This commit is contained in:
Nadav Amit 2019-07-18 15:57:31 -07:00 committed by Linus Torvalds
parent c06306696f
commit 49f17c26c1
1 changed files with 10 additions and 10 deletions
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20
kernel/resource.c
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@ -326,7 +326,7 @@ EXPORT_SYMBOL(release_resource);
* *
* If a resource is found, returns 0 and @*res is overwritten with the part * 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 * 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 * This function walks the whole tree and not just first level children
* unless @first_lvl is true. * unless @first_lvl is true.
@ -365,16 +365,16 @@ static int find_next_iomem_res(resource_size_t start, resource_size_t end,
break; break;
} }
read_unlock(&resource_lock); if (p) {
if (!p) /* copy data */
return -1; res->start = max(start, p->start);
res->end = min(end, p->end);
res->flags = p->flags;
res->desc = p->desc;
}
/* copy data */ read_unlock(&resource_lock);
res->start = max(start, p->start); return p ? 0 : -ENODEV;
res->end = min(end, p->end);
res->flags = p->flags;
res->desc = p->desc;
return 0;
} }
static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end, static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,