Messages in this thread | | | Date | Fri, 07 Jan 2011 16:12:21 +0100 | From | Jiri Slaby <> | Subject | Re: [PATCH 34/36] tty: add 'active' sysfs attribute to tty0 and console device |
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On 01/07/2011 02:20 PM, Kay Sievers wrote: > On Fri, Jan 7, 2011 at 10:09, Jiri Slaby <jslaby@suse.cz> wrote: >> On 01/06/2011 11:23 PM, Greg Kroah-Hartman wrote: >>> --- a/drivers/tty/tty_io.c >>> +++ b/drivers/tty/tty_io.c >>> @@ -3232,9 +3232,45 @@ static int __init tty_class_init(void) >>> postcore_initcall(tty_class_init); >>> >>> /* 3/2004 jmc: why do these devices exist? */ >>> - >>> static struct cdev tty_cdev, console_cdev; >>> >>> +static ssize_t show_cons_active(struct device *dev, >>> + struct device_attribute *attr, char *buf) >>> +{ >>> + struct console *cs[16]; >>> + int i = 0; >>> + struct console *c; >>> + ssize_t count = 0; >>> + >>> + acquire_console_sem(); >>> + for (c = console_drivers; c; c = c->next) { >> >> This should be: >> for_each_console(c) >> like somebody already suggested. > > That's exported now? It was local to printk.c at least that time. > > Anyway, the only sensible change here is to convert that home-grown > ->next thing to a proper kernel linked list, and use the common > iterators instead of doing it on our own, or export new custom ones.
Perhaps -- I didn't look into the code if there is something which blocked this to be done years ago. I doubt there is...
>>> + if (!c->device) >>> + continue; >> >> Why are consoles without devices ignored here? > > It's a common pattern all over the place. What is a "console without a > device" that would be interesting here?
For example parport console. The question is whether you are interested in consoles without ttys in systemd and other potential users.
>> Other than that there are 2 build warnings, see below. >> >>> - device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0"); >>> + tty0dev = device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0"); >>> + if (IS_ERR(tty0dev)) >>> + tty0dev = NULL; >>> + else >>> + device_create_file(tty0dev, &dev_attr_active); >> >> drivers/tty/vt/vt.c: In function ‘vty_init’: >> drivers/tty/vt/vt.c:2997:21: warning: ignoring return value of >> ‘device_create_file’, declared with attribute warn_unused_result > > The code doesn't even check device_create(). :) > > Anyway we actually don't want to check the return value of > file_create(), it's a non-fatal error, if it ever happens.
Ok, but we don't want to introduce new warnings.
> What's the preferred way to do that: > int ignore = device_create_file()
I think the usual workaround in C is casting to void.
regards, -- js suse labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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