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

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

[Jan-Bernd Themann]

Add memory remove hotplug support

Signed-off-by: Jan-Bernd Themann <themann@de.ibm.com>

---
 Comment: This patch depends on the following patch that
 exports the symbols
  register_memory_notifier()
  unregister_memory_notifier()

 http://lkml.org/lkml/2008/2/1/293


 drivers/net/ehea/ehea_main.c |   25 +++++++++++++++++++++++++
 1 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/drivers/net/ehea/ehea_main.c b/drivers/net/ehea/ehea_main.c
index 21af674..b75afcc 100644
--- a/drivers/net/ehea/ehea_main.c
+++ b/drivers/net/ehea/ehea_main.c
@@ -35,6 +35,7 @@
 #include <linux/if_ether.h>
 #include <linux/notifier.h>
 #include <linux/reboot.h>
+#include <linux/memory.h>
 #include <asm/kexec.h>
 
 #include <net/ip.h>
@@ -3480,6 +3481,24 @@ void ehea_crash_handler(void)
 					      0, H_DEREG_BCMC);
 }
 
+static int ehea_mem_notifier(struct notifier_block *nb,
+                             unsigned long action, void *data)
+{
+	switch (action) {
+	case MEM_OFFLINE:
+		ehea_info("memory has been removed");
+		ehea_rereg_mrs(NULL);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block ehea_mem_nb = {
+	.notifier_call = ehea_mem_notifier,
+};
+
 static int ehea_reboot_notifier(struct notifier_block *nb,
 				unsigned long action, void *unused)
 {
@@ -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");
@@ -3582,6 +3605,7 @@ int __init ehea_module_init(void)
 out3:
 	ibmebus_unregister_driver(&ehea_driver);
 out2:
+	unregister_memory_notifier(&ehea_mem_nb);
 	unregister_reboot_notifier(&ehea_reboot_nb);
 	crash_shutdown_unregister(&ehea_crash_handler);
 out:
@@ -3599,6 +3623,7 @@ static void __exit ehea_module_exit(void)
 	ret = crash_shutdown_unregister(&ehea_crash_handler);
 	if (ret)
 		ehea_info("failed unregistering crash handler");
+	unregister_memory_notifier(&ehea_mem_nb);
 	kfree(ehea_fw_handles.arr);
 	kfree(ehea_bcmc_regs.arr);
 	ehea_destroy_busmap();
-- 
1.5.2

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

[Michael Ellerman]

[-- Attachment #1: Type: text/plain, Size: 1515 bytes --]

On Mon, 2008-02-04 at 14:04 +0100, Jan-Bernd Themann wrote:
> Add memory remove hotplug support
> 
> Signed-off-by: Jan-Bernd Themann <themann@de.ibm.com>
> 
> ---
>  Comment: This patch depends on the following patch that
>  exports the symbols
>   register_memory_notifier()
>   unregister_memory_notifier()
> 
>  http://lkml.org/lkml/2008/2/1/293
> 
> 
>  drivers/net/ehea/ehea_main.c |   25 +++++++++++++++++++++++++
>  1 files changed, 25 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/ehea/ehea_main.c b/drivers/net/ehea/ehea_main.c
> index 21af674..b75afcc 100644
> --- a/drivers/net/ehea/ehea_main.c
> +++ b/drivers/net/ehea/ehea_main.c

> @@ -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?

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

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

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

[Jan-Bernd Themann]

On Monday 04 February 2008 15:46, Michael Ellerman wrote:
> On Mon, 2008-02-04 at 14:04 +0100, Jan-Bernd Themann wrote:
> > Add memory remove hotplug support

> > @@ -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.

Regards,
Jan-Bernd

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

[Michael Ellerman]

[-- Attachment #1: Type: text/plain, Size: 1706 bytes --]


On Mon, 2008-02-04 at 16:24 +0100, Jan-Bernd Themann wrote:
> On Monday 04 February 2008 15:46, Michael Ellerman wrote:
> > On Mon, 2008-02-04 at 14:04 +0100, Jan-Bernd Themann wrote:
> > > Add memory remove hotplug support
> 
> > > @@ -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

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 189 bytes --]