Re: [PATCH v5 13/13] tty: gunyah: Add tty console driver for RM Console Services

Jiri Slaby
2022-10-11T06:02:49Z

On 11. 10. 22, 2:08, Elliot Berman wrote:
> Gunyah provides a console for each VM using the VM console resource
> manager APIs. This driver allows console data from other
> VMs to be accessed via a TTY device and exports a console device to dump
> Linux's own logs to our console.
...
> +struct rm_cons_drv_data {
> + struct tty_driver *tty_driver;
> + struct device *dev;
> +
> + spinlock_t ports_lock;
> + struct rm_cons_port *ports[RM_CONS_TTY_ADAPATERS];
> +
> + struct notifier_block rm_cons_notif;
> + struct console console;
> +
> + /* below are for printk console.
> + * gh_rm_console_* calls will sleep and console_write can be called from
> + * atomic ctx. Two xmit buffers are used. The active buffer is tracked with
> + * co_xmit_idx. Writes go into the co_xmit_buf[co_xmit_idx] buffer.
> + * A work is scheduled to flush the bytes. The work will swap the active buffer
> + * and write out the other buffer.
> + */

Ugh, why? This is too ugly and unnecessary. What about passing the kfifo
to gh_rm_console_write() instead? You do memcpy() there anyway.

> + char *co_xmit_buf[2];
> + int co_xmit_idx;
> + unsigned int co_xmit_count;
> + spinlock_t co_xmit_lock;
> + struct work_struct co_flush_work;
> +};
> +
> +static int rm_cons_notif_handler(struct notifier_block *nb, unsigned long cmd, void *data)
> +{
> + int count, i;
> + struct rm_cons_port *rm_port = NULL;
> + struct tty_port *tty_port = NULL;
> + struct rm_cons_drv_data *cons_data =
> + container_of(nb, struct rm_cons_drv_data, rm_cons_notif);
> + const struct gh_rm_notification *notif = data;
> + struct gh_rm_notif_vm_console_chars const * const msg = notif->buff;

So you did not comment on/address all my notes?

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js