Re: [PATCH 2/2] ehea: add memory remove hotplug support

On Mon, 2008-02-04 at 16:24 +0100, Jan-Bernd Themann wrote:

On Monday 04 February 2008 15:46, Michael Ellerman wrote:

quoted

On Mon, 2008-02-04 at 14:04 +0100, Jan-Bernd Themann wrote:

quoted

Add memory remove hotplug support

quoted

quoted

@@ -3559,6 +3578,10 @@ int __init ehea_module_init(void)
 	if (ret)
 		ehea_info("failed registering reboot notifier");
 
+	ret = register_memory_notifier(&ehea_mem_nb);
+	if (ret)
+		ehea_info("failed registering memory remove notifier");

 	ret = crash_shutdown_register(&ehea_crash_handler);
 	if (ret)
 		ehea_info("failed registering crash handler");

You don't do anything except print a message if the registration fails.
What happens when someone tries to remove memory but the memory notifier
wasn't registered properly? Bang?

In case the registration fails and somebody tries to free memory:
- Driver will not remove the affected memory from the eHEA memory region
  --> Firmware (phyp) can not free that memory (as marked as used)
  --> Therefore the removed memory could not be used in an other partition

It makes sense to allow the driver to work anyway. Having no ethernet
would not really be a good alternative.

Yeah I agree. I wasn't clear from the patch that no notifier -> no
memory removed. Rather than, no notifier -> memory removed and ehea
isn't told about it.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person