[PATCH 4.9 78/84] ntb: no sleep in ntb_async_tx_submit

Greg Kroah-Hartman
2017-08-28T08:13:19Z

From: Allen Hubbe <Allen.Hubbe@dell.com>

commit 88931ec3dc11e7dbceb3b0df455693873b508fbe upstream.

Do not sleep in ntb_async_tx_submit, which could deadlock.
This reverts commit "8c874cc140d667f84ae4642bb5b5e0d6396d2ca4"

Fixes: 8c874cc140d6 ("NTB: Address out of DMA descriptor issue with NTB")
Reported-by: Jia-Ju Bai <baijiaju1990@163.com>
Signed-off-by: Allen Hubbe <Allen.Hubbe@dell.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/ntb/ntb_transport.c | 50 ++++++--------------------------------------
1 file changed, 7 insertions(+), 43 deletions(-)

--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -176,14 +176,12 @@ 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 {
@@ -256,8 +254,6 @@ 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 msecs_to_jiffies(50)

static void ntb_transport_rxc_db(unsigned long data);
static const struct ntb_ctx_ops ntb_transport_ops;
@@ -518,12 +514,6 @@ static ssize_t debugfs_read(struct file
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");
@@ -770,8 +760,6 @@ static void ntb_qp_link_down_reset(struc
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)
@@ -1314,7 +1302,6 @@ static int ntb_async_rx_submit(struct nt
struct dmaengine_unmap_data *unmap;
dma_cookie_t cookie;
void *buf = entry->buf;
- int retries = 0;

len = entry->len;
device = chan->device;
@@ -1343,22 +1330,11 @@ static int ntb_async_rx_submit(struct nt

unmap->from_cnt = 1;

- 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++;
+ txd = device->device_prep_dma_memcpy(chan, unmap->addr[1],
+ unmap->addr[0], len,
+ DMA_PREP_INTERRUPT);
+ if (!txd)
goto err_get_unmap;
- }

txd->callback_result = ntb_rx_copy_callback;
txd->callback_param = entry;
@@ -1603,7 +1579,6 @@ static int ntb_async_tx_submit(struct nt
struct dmaengine_unmap_data *unmap;
dma_addr_t dest;
dma_cookie_t cookie;
- int retries = 0;

device = chan->device;
dest = qp->tx_mw_phys + qp->tx_max_frame * entry->tx_index;
@@ -1625,21 +1600,10 @@ static int ntb_async_tx_submit(struct nt

unmap->to_cnt = 1;

- 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++;
+ txd = device->device_prep_dma_memcpy(chan, dest, unmap->addr[0], len,
+ DMA_PREP_INTERRUPT);
+ if (!txd)
goto err_get_unmap;
- }

txd->callback_result = ntb_tx_copy_callback;
txd->callback_param = entry;