Commit e978a3cc authored by Nathan Lynch's avatar Nathan Lynch Committed by Michael Ellerman
Browse files

powerpc/pseries: remove obsolete memory hotplug DT notifier code 



pseries_update_drconf_memory() runs from a DT notifier in response to
an update to the ibm,dynamic-memory property of the
/ibm,dynamic-reconfiguration-memory node. This property is an older
less compact format than the ibm,dynamic-memory-v2 property used in
most currently supported firmwares. There has never been an equivalent
function for the v2 property.

pseries_update_drconf_memory() compares the 'assigned' flag for each
LMB in the old vs new properties and adds or removes the block
accordingly. However it appears to be of no actual utility:

* Partition suspension and PRRNs are specified only to change LMBs'
  NUMA affinity information. This notifier should be a no-op for those
  scenarios since the assigned flags should not change.

* The memory hotplug/DLPAR path has a hack which short-circuits
  execution of the notifier:
     dlpar_memory()
        ...
        rtas_hp_event = true;
        drmem_update_dt()
           of_update_property()
              pseries_memory_notifier()
                 pseries_update_drconf_memory()
                    if (rtas_hp_event) return;

So this code only makes sense as a relic of the time when more of the
DLPAR workflow took place in user space. I don't see a purpose for it
now.

Signed-off-by: default avatarNathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200612051238.1007764-19-nathanl@linux.ibm.com
parent 38c392ce

arch/powerpc/platforms/pseries/hotplug-memory.c

+1 −64
Original line number Diff line number Diff line
@@ -22,8 +22,6 @@ 
#include <asm/drmem.h>

#include "pseries.h"



static bool rtas_hp_event;



unsigned long pseries_memory_block_size(void)

{

	struct device_node *np;
@@ -871,11 +869,8 @@ int dlpar_memory(struct pseries_hp_errorlog *hp_elog) 
		break;

	}



	if (!rc) {

		rtas_hp_event = true;

	if (!rc)

		rc = drmem_update_dt();

		rtas_hp_event = false;

	}



	unlock_device_hotplug();

	return rc;
@@ -911,60 +906,6 @@ static int pseries_add_mem_node(struct device_node *np) 
	return (ret < 0) ? -EINVAL : 0;

}



static int pseries_update_drconf_memory(struct of_reconfig_data *pr)

{

	struct of_drconf_cell_v1 *new_drmem, *old_drmem;

	unsigned long memblock_size;

	u32 entries;

	__be32 *p;

	int i, rc = -EINVAL;



	if (rtas_hp_event)

		return 0;



	memblock_size = pseries_memory_block_size();

	if (!memblock_size)

		return -EINVAL;



	if (!pr->old_prop)

		return 0;



	p = (__be32 *) pr->old_prop->value;

	if (!p)

		return -EINVAL;



	/* The first int of the property is the number of lmb's described

	 * by the property. This is followed by an array of of_drconf_cell

	 * entries. Get the number of entries and skip to the array of

	 * of_drconf_cell's.

	 */

	entries = be32_to_cpu(*p++);

	old_drmem = (struct of_drconf_cell_v1 *)p;



	p = (__be32 *)pr->prop->value;

	p++;

	new_drmem = (struct of_drconf_cell_v1 *)p;



	for (i = 0; i < entries; i++) {

		if ((be32_to_cpu(old_drmem[i].flags) & DRCONF_MEM_ASSIGNED) &&

		    (!(be32_to_cpu(new_drmem[i].flags) & DRCONF_MEM_ASSIGNED))) {

			rc = pseries_remove_memblock(

				be64_to_cpu(old_drmem[i].base_addr),

						     memblock_size);

			break;

		} else if ((!(be32_to_cpu(old_drmem[i].flags) &

			    DRCONF_MEM_ASSIGNED)) &&

			    (be32_to_cpu(new_drmem[i].flags) &

			    DRCONF_MEM_ASSIGNED)) {

			rc = memblock_add(be64_to_cpu(old_drmem[i].base_addr),

					  memblock_size);

			rc = (rc < 0) ? -EINVAL : 0;

			break;

		}

	}

	return rc;

}



static int pseries_memory_notifier(struct notifier_block *nb,

				   unsigned long action, void *data)

{
@@ -978,10 +919,6 @@ static int pseries_memory_notifier(struct notifier_block *nb, 
	case OF_RECONFIG_DETACH_NODE:

		err = pseries_remove_mem_node(rd->dn);

		break;

	case OF_RECONFIG_UPDATE_PROPERTY:

		if (!strcmp(rd->prop->name, "ibm,dynamic-memory"))

			err = pseries_update_drconf_memory(rd);

		break;

	}

	return notifier_from_errno(err);

}

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