lkml.org 
[lkml]   [2019]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] of: Rework and simplify phandle cache to use a fixed size
From
Date
On 12/12/19 7:05 AM, Sebastian Andrzej Siewior wrote:
> On 2019-12-11 17:48:54 [-0600], Rob Herring wrote:
>>> - if (phandle_cache) {
>>> - if (phandle_cache[masked_handle] &&
>>> - handle == phandle_cache[masked_handle]->phandle)
>>> - np = phandle_cache[masked_handle];
>>> - if (np && of_node_check_flag(np, OF_DETACHED)) {
>>> - WARN_ON(1); /* did not uncache np on node removal */
>>> - of_node_put(np);
>>> - phandle_cache[masked_handle] = NULL;
>>> - np = NULL;
>>> - }
>>> + if (phandle_cache[handle_hash] &&
>>> + handle == phandle_cache[handle_hash]->phandle)
>>> + np = phandle_cache[handle_hash];
>>> + if (np && of_node_check_flag(np, OF_DETACHED)) {
>>> + WARN_ON(1); /* did not uncache np on node removal */
>>
>> BTW, I don't think this check is even valid. If we failed to detach
>> and remove the node from the cache, then we could be accessing np
>> after freeing it.
>
> this is kmalloc()ed memory which is always valid. If the memory is

It was kmalloc()ed memory _before_ applying Rob's patch. It no longer
is kmalloc()ed, so the rest of this discussion no longer applies.

-Frank

> already re-used then
> handle == phandle_cache[handle_hash]->phandle
>
> will fail (the check, not the memory access itself). If the check
> remains valid then you can hope for the OF_DETACHED flag to trigger the
> warning.
>
>> Rob
>
> Sebastian
>

\
 
 \ /
  Last update: 2019-12-19 16:34    [W:0.063 / U:3.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site