[openib-general] [PATCH] RDMA/iwcm: Bugs in cm_conn_req_handler()

[Steve Wise]

This looks good for 2.6.21 IMO.

Acked-by: Steve Wise <swise at opengridcomputing.com>


On Wed, 2007-02-07 at 12:26 +0530, Krishna Kumar wrote:
> (I had submitted this once earlier but got no response)
> 
> cm_conn_req_handler() :
> 	1. Calling destroy_cm_id leaks 3 work 'free' list entries.
> 	2. cm_id is freed up wrongly and not cm_id_priv (though the
> 	   effect is the same since cm_id is the first element of
> 	   cm_id_priv, but still a bug if the top level cm_id changes).
> 	3. Reject message has to be sent on failure. Tested this
> 	   without the fix and found the client hangs, waited for about
> 	   20 mins and then did Ctrl-C but the process is unkillable.
> 	4. Setting IWCM_F_CALLBACK_DESTROY on cm_id (child handle)
> 	   doesn't achieve anything, since checking for
> 	   IWCM_F_CALLBACK_DESTROY in the parent's flag (in
> 	   cm_work_handler) means that this will never be true.
> 
> All 4 above cases were tested by injecting random error in
> iw_conn_req_handler() and running rdma_bw/krping, they were
> confirmed. I added the BUG_ON() to confirm the earlier check
> for id_priv->refcount==0 should always be true (and could be
> removed).
> 
> Patch against 2.6.20
> 
> Signed-off-by: Krishna Kumar <krkumar2 at in.ibm.com>
> ---
> diff -ruNp org/drivers/infiniband/core/iwcm.c new/drivers/infiniband/core/iwcm.c
> --- org/drivers/infiniband/core/iwcm.c	2007-01-24 10:25:26.000000000 +0530
> +++ new/drivers/infiniband/core/iwcm.c	2007-01-24 10:25:31.000000000 +0530
> @@ -647,10 +647,9 @@ static void cm_conn_req_handler(struct i
>  	/* Call the client CM handler */
>  	ret = cm_id->cm_handler(cm_id, iw_event);
>  	if (ret) {
> -		set_bit(IWCM_F_CALLBACK_DESTROY, &cm_id_priv->flags);
> -		destroy_cm_id(cm_id);
> -		if (atomic_read(&cm_id_priv->refcount)==0)
> -			kfree(cm_id);
> +		BUG_ON(atomic_read(&cm_id_priv->refcount) != 1);
> +		iw_cm_reject(cm_id, NULL, 0);
> +		iw_destroy_cm_id(cm_id);
>  	}
>  
>  out:
> 
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