Re: A general question on SMP-safe driver code.

From: Alan Cox
Date: Sat Dec 25 2004 - 08:31:54 EST


On Gwe, 2004-12-24 at 22:58, Jim Nelson wrote:
> Looking at a few older drivers, I'm trying to figure out the best ways to handle
> some locking. Using drivers/char/esp.c as an example (since it's the one I'm
> trying to grok right now), here is one example:

> ;
> serial_out(info, UART_ESI_CMD1, ESI_GET_TX_AVAIL);
> spin_unlock_irq(&info->esp_lock);
>
> while ((serial_in(info, UART_ESI_STAT1) != 0x03) ||
> (serial_in(info, UART_ESI_STAT2) != 0xff)) {

You need to guard these as well in the locks. It might actually look a
lot cleaner to have functions esp_send_command(info, a, b) and the like
which do the locking internally ?

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