Re: [PATCH] firmware, memmap: fix firmware_map_entry leak

[Yasuaki Ishimatsu]

2013/04/15 18:03, Tang Chen wrote:
> 
> Reviewed-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>

Thank you for your review.

Thanks,
Yasuaki Ishimatsu

> 
> Thanks. :)
> 
> On 04/15/2013 01:48 PM, Yasuaki Ishimatsu wrote:
>> When hot removing a memory, a firmware_map_entry which has memory range
>> of the memory is released by release_firmware_map_entry(). If the entry
>> is allocated by bootmem, release_firmware_map_entry() adds the entry to
>> map_entires_bootmem list when firmware_map_find_entry() finds the entry
>> from map_entries list. But firmware_map_find_entry never find the entry
>> sicne map_entires list does not have the entry. So the entry just leaks.
>>
>> Here are steps of leaking firmware_map_entry:
>> firmware_map_remove()
>> ->  firmware_map_find_entry()
>>      Find released entry from map_entries list
>> ->  firmware_map_remove_entry()
>>      Delete the entry from map_entries list
>> ->  remove_sysfs_fw_map_entry()
>>      ...
>>      ->  release_firmware_map_entry()
>>         ->  firmware_map_find_entry()
>>            Find the entry from map_entries list but the entry has been
>>            deleted from map_entries list. So the entry is not added
>>            to map_entries_bootmem. Thus the entry leaks
>>
>> release_firmware_map_entry() should not call firmware_map_find_entry()
>> since releaed entry has been deleted from map_entries list.
>> So the patch delete firmware_map_find_entry() from releae_firmware_map_entry()
>>
>> Signed-off-by: Yasuaki Ishimatsu<isimatu.yasuaki@xxxxxxxxxxxxxx>
>> ---
>>    drivers/firmware/memmap.c |    9 +++------
>>    1 files changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
>> index 0b5b5f6..e2e04b0 100644
>> --- a/drivers/firmware/memmap.c
>> +++ b/drivers/firmware/memmap.c
>> @@ -114,12 +114,9 @@ static void __meminit release_firmware_map_entry(struct kobject *kobj)
>>    		 * map_entries_bootmem here, and deleted from&map_entries in
>>    		 * firmware_map_remove_entry().
>>    		 */
>> -		if (firmware_map_find_entry(entry->start, entry->end,
>> -		    entry->type)) {
>> -			spin_lock(&map_entries_bootmem_lock);
>> -			list_add(&entry->list,&map_entries_bootmem);
>> -			spin_unlock(&map_entries_bootmem_lock);
>> -		}
>> +		spin_lock(&map_entries_bootmem_lock);
>> +		list_add(&entry->list,&map_entries_bootmem);
>> +		spin_unlock(&map_entries_bootmem_lock);
>>
>>    		return;
>>    	}
>>
>>


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