Hi,
Yet another convention question regarding device drivers. As you may recall, I'm working on some hardware along with its Linux driver.
I just discovered that under certain conditions, my little piece of hardware may turn unreliable. The blame is on the chip I'm working on, so I can't fix this. Fortunately, the chip tells me something has gone deadly wrong, so the least I can do is to report it to the driver.
PCIe has an error reporting mechanism for this purpose, but I'm not sure if I can rely on errors of that sort being reported loud enough to the user. I want any communication with the device to stop immediately with an error message, or people will start blaming me for data being messed up (which is what the error is about).
The brute-force way to do this is to check a device-global flag every invocation of read(), write(), and other relevant methods. Maybe also before returning a successful value. If the flag is set ( = problem detected) return some -EDROPDEAD, so that application software reacts, and maybe someone will go to /var/log/messages to get a better idea of what happened. (I think I'll settle for -ENODEV)
So here comes my question: Is there a convention for how a device driver can tell the kernel that certain devices (as in /dev/something) have turned unusable, in particular when some of them are already open? I guess this is related to hotpluggable devices, but in the latter case I suppose it's the kernel informing the device driver about the event, and not vice versa.
Thanks in advance and see you tomorrow. Eli -- Web: http://www.billauer.co.il _______________________________________________ Haifux mailing list Haifux@haifux.org http://hamakor.org.il/cgi-bin/mailman/listinfo/haifux
