On Sat, Oct 09, 2021 at 07:48:28PM +0800, Xianting Tian wrote:
> --- a/drivers/tty/hvc/hvc_console.h
> +++ b/drivers/tty/hvc/hvc_console.h
> @@ -32,13 +32,21 @@
> */
> #define HVC_ALLOC_TTY_ADAPTERS 8
>
> +/*
> + * These sizes are most efficient for vio, because they are the
> + * native transfer size. We could make them selectable in the
> + * future to better deal with backends that want other buffer sizes.
> + */
> +#define N_OUTBUF 16
> +#define N_INBUF 16
> +
> +#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
Does this conflict with what is in hvcs.c?
> +
> struct hvc_struct {
> struct tty_port port;
> spinlock_t lock;
> int index;
> int do_wakeup;
> - char *outbuf;
> - int outbuf_size;
> int n_outbuf;
> uint32_t vtermno;
> const struct hv_ops *ops;
> @@ -48,6 +56,18 @@ struct hvc_struct {
> struct work_struct tty_resize;
> struct list_head next;
> unsigned long flags;
> +
> + /* the buf is used in hvc console api for putting chars */
> + char cons_outbuf[N_OUTBUF] __ALIGNED__;
> + spinlock_t cons_outbuf_lock;
Did you look at the placement using pahole as to how this structure now
looks?
> +
> + /* the buf is for putting single char to tty */
> + char outchar;
> + spinlock_t outchar_lock;
So you have a lock for a character and a different one for a longer
string? Why can they not just use the same lock? Why are 2 needed at
all, can't you just use the first character of cons_outbuf[] instead?
Surely you do not have 2 sends happening at the same time, right?
> +
> + /* the buf is for putting chars to tty */
> + int outbuf_size;
> + char outbuf[0] __ALIGNED__;
I thought we were not allowing [0] anymore in kernel structures?
thanks,
greg k-h
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