[PATCH AUTOSEL 5.2 43/76] ibmvnic: Unmap DMA address of TX descriptor buffers after use

Sasha Levin
2019-08-29T18:14:49Z

From: Thomas Falcon <tlfalcon@linux.ibm.com>

[ Upstream commit 80f0fe0934cd3daa13a5e4d48a103f469115b160 ]

There's no need to wait until a completion is received to unmap
TX descriptor buffers that have been passed to the hypervisor.
Instead unmap it when the hypervisor call has completed. This patch
avoids the possibility that a buffer will not be unmapped because
a TX completion is lost or mishandled.

Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Tested-by: Devesh K. Singh <devesh_singh@in.ibm.com>
Signed-off-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/ibm/ibmvnic.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 3da6800732656..cebd20f3128d4 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1568,6 +1568,8 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, struct net_device *netdev)
lpar_rc = send_subcrq_indirect(adapter, handle_array[queue_num],
(u64)tx_buff->indir_dma,
(u64)num_entries);
+ dma_unmap_single(dev, tx_buff->indir_dma,
+ sizeof(tx_buff->indir_arr), DMA_TO_DEVICE);
} else {
tx_buff->num_entries = num_entries;
lpar_rc = send_subcrq(adapter, handle_array[queue_num],
@@ -2788,7 +2790,6 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter,
union sub_crq *next;
int index;
int i, j;
- u8 *first;

restart_loop:
while (pending_scrq(adapter, scrq)) {
@@ -2818,14 +2819,6 @@ static int ibmvnic_complete_tx(struct ibmvnic_adapter *adapter,

txbuff->data_dma[j] = 0;
}
- /* if sub_crq was sent indirectly */
- first = &txbuff->indir_arr[0].generic.first;
- if (*first == IBMVNIC_CRQ_CMD) {
- dma_unmap_single(dev, txbuff->indir_dma,
- sizeof(txbuff->indir_arr),
- DMA_TO_DEVICE);
- *first = 0;
- }

if (txbuff->last_frag) {
dev_kfree_skb_any(txbuff->skb);
--
2.20.1