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virtio: console: Prepare for writing to userspace buffers 

When ports get advertised as char devices, the buffers will come from
userspace. Equip the fill_readbuf function with the ability to write
to userspace buffers.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Amit Shah 2009-12-21 21:26:45 +05:30 committed by Rusty Russell
parent 17634ba255
commit b766ceed5b
1 changed files with 14 additions and 6 deletions
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20
drivers/char/virtio_console.c
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@ -358,7 +358,8 @@ fail:
* Give out the data that's requested from the buffer that we have * Give out the data that's requested from the buffer that we have
* queued up. * queued up.
*/ */
static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count) static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
bool to_user)
{ {
struct port_buffer *buf; struct port_buffer *buf;
unsigned long flags; unsigned long flags;
@ -367,12 +368,18 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
return 0; return 0;
buf = port->inbuf; buf = port->inbuf;
if (out_count > buf->len - buf->offset) out_count = min(out_count, buf->len - buf->offset);
out_count = buf->len - buf->offset;
memcpy(out_buf, buf->buf + buf->offset, out_count); if (to_user) {
ssize_t ret;
ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count);
if (ret)
return -EFAULT;
} else {
memcpy(out_buf, buf->buf + buf->offset, out_count);
}
/* Return the number of bytes actually copied */
buf->offset += out_count; buf->offset += out_count;
if (buf->offset == buf->len) { if (buf->offset == buf->len) {
@ -388,6 +395,7 @@ static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count)
spin_unlock_irqrestore(&port->inbuf_lock, flags); spin_unlock_irqrestore(&port->inbuf_lock, flags);
} }
/* Return the number of bytes actually copied */
return out_count; return out_count;
} }
@ -431,7 +439,7 @@ static int get_chars(u32 vtermno, char *buf, int count)
/* If we don't have an input queue yet, we can't get input. */ /* If we don't have an input queue yet, we can't get input. */
BUG_ON(!port->in_vq); BUG_ON(!port->in_vq);
return fill_readbuf(port, buf, count); return fill_readbuf(port, buf, count, false);
} }
static void resize_console(struct port *port) static void resize_console(struct port *port)