[PATCH AUTOSEL 4.20 093/304] sunvdc: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN

Sasha Levin
2019-01-28T17:45:46Z

From: Young Xiao <YangX92@hotmail.com>

[ Upstream commit a11f6ca9aef989b56cd31ff4ee2af4fb31a172ec ]

__vdc_tx_trigger should only loop on EAGAIN a finite
number of times.

See commit adddc32d6fde ("sunvnet: Do not spin in an
infinite loop when vio_ldc_send() returns EAGAIN") for detail.

Signed-off-by: Young Xiao <YangX92@hotmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/sunvdc.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
index b54fa6726303..6b7b0d8a2acb 100644
--- a/drivers/block/sunvdc.c
+++ b/drivers/block/sunvdc.c
@@ -45,6 +45,8 @@ MODULE_VERSION(DRV_MODULE_VERSION);
#define WAITING_FOR_GEN_CMD 0x04
#define WAITING_FOR_ANY -1

+#define VDC_MAX_RETRIES 10
+
static struct workqueue_struct *sunvdc_wq;

struct vdc_req_entry {
@@ -431,6 +433,7 @@ static int __vdc_tx_trigger(struct vdc_port *port)
.end_idx = dr->prod,
};
int err, delay;
+ int retries = 0;

hdr.seq = dr->snd_nxt;
delay = 1;
@@ -443,6 +446,8 @@ static int __vdc_tx_trigger(struct vdc_port *port)
udelay(delay);
if ((delay <<= 1) > 128)
delay = 128;
+ if (retries++ > VDC_MAX_RETRIES)
+ break;
} while (err == -EAGAIN);

if (err == -ENOTCONN)
--
2.19.1