linux-kernel - [PATCH v12 2/2] virtio-console: remove unnecessary kmemdup()

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Date:   Thu, 28 Oct 2021 23:09:54 +0800
From:   Xianting Tian <xianting.tian@...ux.alibaba.com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org, amit@...nel.org,
        arnd@...db.de, osandov@...com
Cc:     shile.zhang@...ux.alibaba.com, sfr@...b.auug.org.au,
        linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org,
        Xianting Tian <xianting.tian@...ux.alibaba.com>
Subject: [PATCH v12 2/2] virtio-console: remove unnecessary kmemdup()

This revert commit c4baad5029 ("virtio-console: avoid DMA from stack")

hvc framework will never pass stack memory to the put_chars() function,
So the calling of kmemdup() is unnecessary, we can remove it.

Signed-off-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
Reviewed-by: Shile Zhang <shile.zhang@...ux.alibaba.com>
---
 drivers/char/virtio_console.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 7eaf303a7..4ed3ffb1d 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1117,8 +1117,6 @@ static int put_chars(u32 vtermno, const char *buf, int count)
 {
 	struct port *port;
 	struct scatterlist sg[1];
-	void *data;
-	int ret;
 
 	if (unlikely(early_put_chars))
 		return early_put_chars(vtermno, buf, count);
@@ -1127,14 +1125,8 @@ static int put_chars(u32 vtermno, const char *buf, int count)
 	if (!port)
 		return -EPIPE;
 
-	data = kmemdup(buf, count, GFP_ATOMIC);
-	if (!data)
-		return -ENOMEM;
-
-	sg_init_one(sg, data, count);
-	ret = __send_to_port(port, sg, 1, count, data, false);
-	kfree(data);
-	return ret;
+	sg_init_one(sg, buf, count);
+	return __send_to_port(port, sg, 1, count, (void *)buf, false);
 }
 
 /*
-- 
2.17.1