linux-kernel - Re: [PATCH 1/3] resource: Fix locking in find_next_iomem

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Message-Id: <20190617212605.bb8cc4571ee67879033e1bc4@linux-foundation.org>
Date:   Mon, 17 Jun 2019 21:26:05 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Nadav Amit <namit@...are.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        stable@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Toshi Kani <toshi.kani@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 1/3] resource: Fix locking in find_next_iomem_res()

On Wed, 12 Jun 2019 21:59:01 -0700 Nadav Amit <namit@...are.com> wrote:

> 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.

Looks right to me.

> 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.

The kerneldoc needs a resync:

--- a/kernel/resource.c~resource-fix-locking-in-find_next_iomem_res-fix
+++ a/kernel/resource.c
@@ -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.
_