linux-kernel - [PATCH AUTOSEL 4.4 22/80] sunvdc: Do not spin in an infinite loop when vio_ldc

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Message-Id: <20190128162401.58841-22-sashal@kernel.org>
Date:   Mon, 28 Jan 2019 11:23:03 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Young Xiao <YangX92@...mail.com>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>, linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 22/80] sunvdc: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN

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

diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
index 4b911ed96ea3..31219fb9e7f4 100644
--- a/drivers/block/sunvdc.c
+++ b/drivers/block/sunvdc.c
@@ -40,6 +40,8 @@ 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 {
@@ -419,6 +421,7 @@ 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;
@@ -431,6 +434,8 @@ 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