On 06. 03. 23, 10:04, Lee Jones wrote:
On Mon, 06 Mar 2023, Jiri Slaby wrote:
On 03. 03. 23, 15:11, Lee Jones wrote:
On Wed, 22 Feb 2023, Florian Eckert wrote:
@@ -113,21 +207,38 @@ static void ledtrig_tty_work(struct work_struct *work)
trigger_data->tty = tty;
}
- ret = tty_get_icount(trigger_data->tty, &icount);
- if (ret) {
- dev_info(trigger_data->tty->dev, "Failed to get icount, stopped polling\n");
- mutex_unlock(&trigger_data->mutex);
- return;
- }
-
- if (icount.rx != trigger_data->rx ||
- icount.tx != trigger_data->tx) {
- led_set_brightness_sync(trigger_data->led_cdev, LED_ON);
-
- trigger_data->rx = icount.rx;
- trigger_data->tx = icount.tx;
- } else {
- led_set_brightness_sync(trigger_data->led_cdev, LED_OFF);
+ switch (trigger_data->mode) {
+ case TTY_LED_CTS:
+ ledtrig_tty_flags(trigger_data, TIOCM_CTS);
+ break;
+ case TTY_LED_DSR:
+ ledtrig_tty_flags(trigger_data, TIOCM_DSR);
+ break;
+ case TTY_LED_CAR:
+ ledtrig_tty_flags(trigger_data, TIOCM_CAR);
+ break;
+ case TTY_LED_RNG:
+ ledtrig_tty_flags(trigger_data, TIOCM_RNG);
+ break;
+ case TTY_LED_CNT:
I believe this requires a 'fall-through' statement.
I don't think this is the case. Isn't fallthrough required only in cases
when there is at least one statement, i.e. a block?
There's no mention of this caveat in the document.
To my untrained eyes, the rule looks fairly explicit, starting with "All".
"
All switch/case blocks must end in one of:
* break;
* fallthrough;
* continue;
* goto <label>;
* return [expression];
"
If you're aware of something I'm not, please consider updating the doc.
The magic word in the above is "block", IMO. A block is defined for me
as a list of declarations and/or statements. Which is not the case in
the above (i.e. in sequential "case"s).
Furthermore, the gcc docs specifically say about fallthrough attribute:
It can only be used in a switch statement (the compiler will issue an
error otherwise), after a preceding statement and before a logically
succeeding case label, or user-defined label.
While "case X:" is technically a (label) statement, I don't think they
were thinking of it as such here due to following "succeeding case
label" in the text.
So checking with the code, gcc indeed skips those
(should_warn_for_implicit_fallthrough()):
/* Skip all immediately following labels. */
while (!gsi_end_p (gsi)
&& (gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL
|| gimple_code (gsi_stmt (gsi)) == GIMPLE_PREDICT))
gsi_next_nondebug (&gsi);
Apart from that, fallthrough only makes the code harder to read:
case X:
case Y:
case Z:
default:
do_something();
VS
case X:
fallthrough;
case Y:
fallthrough;
case Z:
fallthrough;
default:
do_something();
The first one is a clear win, IMO, and it's pretty clear that it falls
through on purpose. And even for compiler -- it shall not produce a
warning in that case.
regards,
--
js
suse labs
