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List:       linux-aio
Subject:    Re: [patch] aio: lookup_ioctx can return the wrong value when looking
From:       Zach Brown <zach.brown () oracle ! com>
Date:       2009-03-18 22:28:24
Message-ID: 49C17588.4080101 () oracle ! com
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>> Thanks to Zach for pointing out that hlist_for_each_entry_rcu will not
>> return with a NULL tpos at the end of the loop, even if the entry was
>> not found.

>> diff --git a/fs/aio.c b/fs/aio.c
>> index 8fa77e2..07c44f0 100644
>> --- a/fs/aio.c
>> +++ b/fs/aio.c
>> @@ -571,7 +571,7 @@ int aio_put_req(struct kiocb *req)
>>  static struct kioctx *lookup_ioctx(unsigned long ctx_id)
>>  {
>>  	struct mm_struct *mm = current->mm;
>> -	struct kioctx *ctx = NULL;
>> +	struct kioctx *ctx, *ret = NULL;
>>  	struct hlist_node *n;
>>  
>>  	rcu_read_lock();
>> @@ -579,12 +579,13 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
>>  	hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
>>  		if (ctx->user_id == ctx_id && !ctx->dead) {
>>  			get_ioctx(ctx);
>> +			ret = ctx;
>>  			break;
>>  		}
>>  	}
>>  
>>  	rcu_read_unlock();
>> -	return ctx;
>> +	return ret;
>>  }
>>  
>>  /*
> 
> Thanks.  I added your signed-off-by: to this commit.

Feel free to add my ack, too:

Acked-By: Zach Brown <zach.brown@oracle.com>

- z

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