Re: [Xen-devel] [PATCH 15/25 v6] xen/arm: vpl011: Add a new console_evtchn_unmask function in xenconsole

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Jul 17, 2017 at 06:36:45PM +0530, Bhupinder Thakur wrote:
> This patch introduces a new console_evtchn_unmask function. This function
> unmasks the console event channel if it is masked for some timeout
> period.
> 
> Signed-off-by: Bhupinder Thakur <bhupinder.thakur@xxxxxxxxxx>
> ---
> CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> 
> Changes since v5:
> - Split this change in a separate patch.
> 
>  tools/console/daemon/io.c | 44 +++++++++++++++++++++++++++-----------------
>  1 file changed, 27 insertions(+), 17 deletions(-)
> 
> diff --git a/tools/console/daemon/io.c b/tools/console/daemon/io.c
> index 6321d78..c272fe6 100644
> --- a/tools/console/daemon/io.c
> +++ b/tools/console/daemon/io.c
> @@ -117,6 +117,11 @@ struct domain {
>  
>  static struct domain *dom_head;
>  
> +static inline bool console_enabled(struct console *con)
> +{
> +     return con->local_port != -1;
> +}
> +
>  static int write_all(int fd, const char* buf, size_t len)
>  {
>       while (len) {
> @@ -909,6 +914,27 @@ static void handle_tty_write(struct console *con)
>       }
>  }
>  
> +static void console_evtchn_unmask(struct console *con, void *data)

No need to use void*.

> +{
> +     long long now = (long long)data;
> +
> +     if (!console_enabled(con))
> +             return;
> +
> +     /* CS 16257:955ee4fa1345 introduces a 5ms fuzz
> +      * for select(), it is not clear poll() has
> +      * similar behavior (returning a couple of ms
> +      * sooner than requested) as well. Just leave
> +      * the fuzz here. Remove it with a separate
> +      * patch if necessary */
> +     if ((now+5) > con->next_period) {
> +             con->next_period = now + RATE_LIMIT_PERIOD;
> +             if (con->event_count >= RATE_LIMIT_ALLOWANCE)
> +                     (void)xenevtchn_unmask(con->xce_handle, 
> con->local_port);
> +             con->event_count = 0;
> +     }
> +}
> +
>  static void handle_ring_read(struct domain *dom)
>  {
>       xenevtchn_port_or_error_t port;
> @@ -1144,23 +1170,7 @@ void handle_io(void)
>               for (d = dom_head; d; d = d->next) {
>                       struct console *con = &d->console;
>  
> -                     /* CS 16257:955ee4fa1345 introduces a 5ms fuzz
> -                      * for select(), it is not clear poll() has
> -                      * similar behavior (returning a couple of ms
> -                      * sooner than requested) as well. Just leave
> -                      * the fuzz here. Remove it with a separate
> -                      * patch if necessary */
> -                     if ((now+5) > con->next_period) {
> -                             con->next_period = now + RATE_LIMIT_PERIOD;
> -                             if (con->event_count >= RATE_LIMIT_ALLOWANCE) {
> -                                     (void)xenevtchn_unmask(con->xce_handle, 
> con->local_port);
> -                             }
> -                             con->event_count = 0;
> -                     }
> -             }
> -
> -             for (d = dom_head; d; d = d->next) {
> -                     struct console *con = &d->console;
> +                     console_evtchn_unmask(con, (void *)now);
>  

You need to keep the two loops, or you need to state why you merge them
into one in the commit message.

>                       add_console_evtchn_fd(con, (void *)&next_timeout);
>  
> -- 
> 2.7.4
> 

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