[PATCH AUTOSEL 4.19 079/258] sunvdc: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN

[Sasha Levin]

From: Young Xiao <yang...@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 <yang...@hotmail.com>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Sasha Levin <sas...@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 f68e9baffad7..5d7024057540 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