Re: [PATCH 2/2] virtio-console: remove unnecessary kmemdup()
From: Jiri Slaby <jirislaby@kernel.org>
Date: 2021-08-02 07:25:18
Also in:
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Hi, why is this 2/2? I seem (Lore neither) to find 1/2. On 01. 08. 21, 7:16, Xianting Tian wrote:
hvc framework will never pass stack memory to the put_chars() function,
Am I blind or missing something?
hvc_console_print(...)
{
char c[N_OUTBUF]
...
cons_ops[index]->put_chars(vtermnos[index], c, i);
The same here:
hvc_poll_put_char(..., char ch)
{
...
n = hp->ops->put_chars(hp->vtermno, &ch, 1);
AFAICS both of them *pass* a pointer to stack variable.
So the calling of kmemdup() is unnecessary, remove it.
Fixes: c4baad5029 ("virtio-console: avoid DMA from stack")This patch doesn't "Fix" -- it reverts the commit. You should've CCed the author too.
quoted hunk ↗ jump to hunk
Signed-off-by: Xianting Tian <redacted> --- 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); } /*
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