Re: [PATCH v6] i2c: virtio: add a virtio i2c frontend driver

[Jason Wang]

On 2021/3/10 10:22 上午, Jie Deng wrote:
> On 2021/3/4 17:15, Jason Wang wrote:
> > > +        }
> > > +
> > > +        if (msgs[i].flags & I2C_M_RD)
> > > +            memcpy(msgs[i].buf, req->buf, msgs[i].len);
> >
> >
> > Sorry if I had asked this before but any rason not to use msg[i].buf 
> > directly?
> The msg[i].buf is passed by the I2C core. I just noticed that these 
> bufs are not
> always allocated by kmalloc. They may come from the stack, which may 
> cause
> the check "sg_init_one -> sg_set_buf -> virt_addr_valid"  to fail. 
> Therefore the
> msg[i].buf is not suitable for direct use here.
>
> Regards.


Right, stack is virtually mapped.

Thanks