Commit b71ec952 authored by Thomas Falcon's avatar Thomas Falcon Committed by David S. Miller
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ibmvnic: Ensure that SCRQ entry reads are correctly ordered 



Ensure that received Subordinate Command-Response Queue (SCRQ)
entries are properly read in order by the driver. These queues
are used in the ibmvnic device to process RX buffer and TX completion
descriptors. dma_rmb barriers have been added after checking for a
pending descriptor to ensure the correct descriptor entry is checked
and after reading the SCRQ descriptor to ensure the entire
descriptor is read before processing.

Fixes: 032c5e82 ("Driver for IBM System i/p VNIC protocol")
Signed-off-by: default avatarThomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 237f977a

drivers/net/ethernet/ibm/ibmvnic.c

+18 −0
Original line number Diff line number Diff line
@@ -2404,6 +2404,12 @@ static int ibmvnic_poll(struct napi_struct *napi, int budget) 


		if (!pending_scrq(adapter, adapter->rx_scrq[scrq_num]))

			break;

		/* The queue entry at the current index is peeked at above

		 * to determine that there is a valid descriptor awaiting

		 * processing. We want to be sure that the current slot

		 * holds a valid descriptor before reading its contents.

		 */

		dma_rmb();

		next = ibmvnic_next_scrq(adapter, adapter->rx_scrq[scrq_num]);

		rx_buff =

		    (struct ibmvnic_rx_buff *)be64_to_cpu(next->
@@ -3113,6 +3119,13 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter, 
		unsigned int pool = scrq->pool_index;

		int num_entries = 0;



		/* The queue entry at the current index is peeked at above

		 * to determine that there is a valid descriptor awaiting

		 * processing. We want to be sure that the current slot

		 * holds a valid descriptor before reading its contents.

		 */

		dma_rmb();



		next = ibmvnic_next_scrq(adapter, scrq);

		for (i = 0; i < next->tx_comp.num_comps; i++) {

			if (next->tx_comp.rcs[i]) {
@@ -3513,6 +3526,11 @@ static union sub_crq *ibmvnic_next_scrq(struct ibmvnic_adapter *adapter, 
	}

	spin_unlock_irqrestore(&scrq->lock, flags);



	/* Ensure that the entire buffer descriptor has been

	 * loaded before reading its contents

	 */

	dma_rmb();



	return entry;

}