在 2021/8/2 下午4:40, Jiri Slaby 写道:

On 02. 08. 21, 10:32, Xianting Tian wrote:

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在 2021/8/2 下午3:25, Jiri Slaby 写道:

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Hi,

why is this 2/2? I seem (Lore neither) to find 1/2.

You didn't receive 1/2?
[PATCH 1/2] tty: hvc: pass DMA capable memory to put_chars()
https://lkml.org/lkml/2021/8/1/8 <https://lkml.org/lkml/2021/8/1/8>

Oh, I did, but it's not properly threaded. PLease fix your setup.

Ok, thanks

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On 01. 08. 21, 7:16, Xianting Tian wrote:

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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.

yes, I discussed the issue with Arnd before in below thread, you can 
get the history, thanks

https://lkml.org/lkml/2021/7/27/494 
<https://lkml.org/lkml/2021/7/27/494>

So is this a v2? You should have noted that. And what changed from v1 
too.

I think yes, I should mentioned it in this patch, sorry for that:(

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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.

yes, we discussed ther issue in above thread, which we CCed the author.

I don't see any input from the author?


Anyway, 1/2 does not even build, so you will send v3 with all the 
above fixed, hopefully.

yes, I will send v3 patch after I figured out a better solution based on 
Arnd's comments for the patch '1/2'.

Do you have any other suggestion for the solution?

thanks.

thanks,