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NTB: Address out of DMA descriptor issue with NTB

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The transport right now does not handle the case where we run out of DMA
descriptors. We just fail when we do not succeed. Adding code to retry for
a bit attempting to use the DMA engine instead of instantly fail to CPU
copy.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Allen Hubbe <Allen.Hubbe@emc.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
This commit is contained in:
Dave Jiang 2016-01-08 09:51:05 -07:00 committed by Jon Mason
parent 703872c2c5
commit 8c874cc140
1 changed files with 41 additions and 7 deletions
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48
drivers/ntb/ntb_transport.c
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@ -171,12 +171,14 @@ struct ntb_transport_qp {
u64 rx_err_ver;
u64 rx_memcpy;
u64 rx_async;
u64 dma_rx_prep_err;
u64 tx_bytes;
u64 tx_pkts;
u64 tx_ring_full;
u64 tx_err_no_buf;
u64 tx_memcpy;
u64 tx_async;
u64 dma_tx_prep_err;
};
struct ntb_transport_mw {
@ -249,6 +251,8 @@ enum {
#define QP_TO_MW(nt, qp) ((qp) % nt->mw_count)
#define NTB_QP_DEF_NUM_ENTRIES 100
#define NTB_LINK_DOWN_TIMEOUT 10
#define DMA_RETRIES 20
#define DMA_OUT_RESOURCE_TO 50
static void ntb_transport_rxc_db(unsigned long data);
static const struct ntb_ctx_ops ntb_transport_ops;
@ -501,6 +505,12 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count,
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"free tx - \t%u\n",
ntb_transport_tx_free_entry(qp));
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"DMA tx prep err - \t%llu\n",
qp->dma_tx_prep_err);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"DMA rx prep err - \t%llu\n",
qp->dma_rx_prep_err);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"\n");
@ -726,6 +736,8 @@ static void ntb_qp_link_down_reset(struct ntb_transport_qp *qp)
qp->tx_err_no_buf = 0;
qp->tx_memcpy = 0;
qp->tx_async = 0;
qp->dma_tx_prep_err = 0;
qp->dma_rx_prep_err = 0;
}
static void ntb_qp_link_cleanup(struct ntb_transport_qp *qp)
@ -1228,6 +1240,7 @@ static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset)
struct dmaengine_unmap_data *unmap;
dma_cookie_t cookie;
void *buf = entry->buf;
int retries = 0;
len = entry->len;
@ -1263,11 +1276,21 @@ static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset)
unmap->from_cnt = 1;
txd = device->device_prep_dma_memcpy(chan, unmap->addr[1],
unmap->addr[0], len,
DMA_PREP_INTERRUPT);
if (!txd)
for (retries = 0; retries < DMA_RETRIES; retries++) {
txd = device->device_prep_dma_memcpy(chan, unmap->addr[1],
unmap->addr[0], len,
DMA_PREP_INTERRUPT);
if (txd)
break;
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(DMA_OUT_RESOURCE_TO);
}
if (!txd) {
qp->dma_rx_prep_err++;
goto err_get_unmap;
}
txd->callback = ntb_rx_copy_callback;
txd->callback_param = entry;
@ -1460,6 +1483,7 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
void __iomem *offset;
size_t len = entry->len;
void *buf = entry->buf;
int retries = 0;
offset = qp->tx_mw + qp->tx_max_frame * qp->tx_index;
hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header);
@ -1494,10 +1518,20 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
unmap->to_cnt = 1;
txd = device->device_prep_dma_memcpy(chan, dest, unmap->addr[0], len,
DMA_PREP_INTERRUPT);
if (!txd)
for (retries = 0; retries < DMA_RETRIES; retries++) {
txd = device->device_prep_dma_memcpy(chan, dest, unmap->addr[0],
len, DMA_PREP_INTERRUPT);
if (txd)
break;
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(DMA_OUT_RESOURCE_TO);
}
if (!txd) {
qp->dma_tx_prep_err++;
goto err_get_unmap;
}
txd->callback = ntb_tx_copy_callback;
txd->callback_param = entry;