netdev - Re: [PATCH net v3] ibmvnic fix NULL tx_pools and rx_tools issue at do

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Message-Id: <20200825.173104.1541443546408114168.davem@davemloft.net>
Date:   Tue, 25 Aug 2020 17:31:04 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     drt@...ux.ibm.com
Cc:     netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        mmc@...ux.vnet.ibm.com
Subject: Re: [PATCH net v3] ibmvnic fix NULL tx_pools and rx_tools issue at
 do_reset

From: Dany Madden <drt@...ux.ibm.com>
Date: Tue, 25 Aug 2020 13:26:41 -0400

> From: Mingming Cao <mmc@...ux.vnet.ibm.com>
> 
> At the time of do_rest, ibmvnic tries to re-initalize the tx_pools
> and rx_pools to avoid re-allocating the long term buffer. However
> there is a window inside do_reset that the tx_pools and
> rx_pools were freed before re-initialized making it possible to deference
> null pointers.
> 
> This patch fix this issue by always check the tx_pool
> and rx_pool are not NULL after ibmvnic_login. If so, re-allocating
> the pools. This will avoid getting into calling reset_tx/rx_pools with
> NULL adapter tx_pools/rx_pools pointer. Also add null pointer check in
> reset_tx_pools and reset_rx_pools to safe handle NULL pointer case.
> 
> Signed-off-by: Mingming Cao <mmc@...ux.vnet.ibm.com>
> Signed-off-by: Dany Madden <drt@...ux.ibm.com>

Applied, but:

> +	if (!adapter->rx_pool)
> +		return -1;
> +

This driver has poor error code usage, it's a random mix of hypervisor
error codes, normal error codes like -EINVAL, and internal error codes.
Sometimes used all in the same function.

For example:

static int ibmvnic_send_crq(struct ibmvnic_adapter *adapter,
			    union ibmvnic_crq *crq)
 ...
	if (!adapter->crq.active &&
	    crq->generic.first != IBMVNIC_CRQ_INIT_CMD) {
		dev_warn(dev, "Invalid request detected while CRQ is inactive, possible device state change during reset\n");
		return -EINVAL;
	}
 ...
	rc = plpar_hcall_norets(H_SEND_CRQ, ua,
				cpu_to_be64(u64_crq[0]),
				cpu_to_be64(u64_crq[1]));

	if (rc) {
		if (rc == H_CLOSED) {
 ...
	return rc;

So obviously this function returns a mix of negative erro codes
and Hypervisor codes such as H_CLOSED.

And stuff like:

	rc = __ibmvnic_open(netdev);
	if (rc)
		return IBMVNIC_OPEN_FAILED;