On 16/03/17 13:36, Russell King - ARM Linux wrote:

On Thu, Mar 16, 2017 at 05:56:53PM +0530, Vignesh R wrote:

quoted

Using dev_name() as irq name during request_irq() might be misleading in
case of serial over PCI. Therefore use a better alternative name for
identifying serial port irqs as "serial" appended with serial_index of
the port. This ensures that "serial" string is always present in irq
name while port index will help in distinguishing b/w different ports.

Wouldn't it be better to use the device name (iow, ttySx) rather than
"serialx" ?

Maybe a helper function in serial_core.c to format the device name into
a supplied string, which can be re-used elsewhere, eg, uart_report_port()
and uart_suspend_port().  IOW:

const char *uart_port_name(char *buf, size_t n, struct uart_driver *drv,
			   struct uart_port *port)
{
	snprintf(buf, n, "%s%d", drv->dev_name,
		 drv->tty_driver->name_base + port->line);

	return buf;
}

which means you can do this:

	char name[16];

	request_irq(..., uart_port_name(name, sizeof(name), driver, port), ...)

which also avoids the allocation.

...and makes 'cat /proc/interrupts' particularly fun later:

  8:          0          GICv2  72 Level     ??h	????V!

Unless a suitably long-lived string already exists somewhere else in the
serial core, the allocation is unavoidable, although kasprintf() (or its
devm_ variant) might make matters a little simpler.

Robin.

 8250 device names are always "ttyS"
plus a number, so 16 characters (including NULL terminator) should be
more than sufficient, and that's most likely true of all serial drivers.
(The longest device name I'm aware of is ttyAMA plus a small integer
for PL011 ports.)