On Sat, 2022-04-23 at 01:25 +0530, Jagdish Gediya wrote: > Current /sys/devices/system/node/* interface doesn't support > to write node_states[], however write support is needed in case > users want to set them manually e.g. when user want to override > default N_DEMOTION_TARGETS found by the kernel. > > Rename existing _NODE_ATTR to _NODE_ATTR_RO and introduce new > _NODE_ATTR_RW which can be used for node_states[] which can > be written from sysfs. > > It may be necessary to validate written values and take action > based on them in a state specific way so a callback 'write' is > introduced in 'struct node_attr'. > > A new function demotion_targets_write() is added to validate > the input nodes for N_DEMOTION_TARGETS which should be subset > of N_MEMORY and to build new demotion list based on new nodes. > > Signed-off-by: Jagdish Gediya <jvgediya@xxxxxxxxxxxxx> How about discussing the ABI design firstly? I started a discussion in the following thread. I think we can start with the requirements. https://lore.kernel.org/lkml/200e95cf36c1642512d99431014db8943fed715d.camel@xxxxxxxxx/ Best Regards, Huang, Ying > --- > drivers/base/node.c | 62 +++++++++++++++++++++++++++++++++++---------- > 1 file changed, 49 insertions(+), 13 deletions(-) > > diff --git a/drivers/base/node.c b/drivers/base/node.c > index 6eef22e6413e..e03eedbc421b 100644 > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -20,6 +20,7 @@ > #include <linux/pm_runtime.h> > #include <linux/swap.h> > #include <linux/slab.h> > +#include <linux/migrate.h> > > > > > static struct bus_type node_subsys = { > .name = "node", > @@ -1013,6 +1014,7 @@ void unregister_one_node(int nid) > struct node_attr { > struct device_attribute attr; > enum node_states state; > + int (*write)(nodemask_t nodes); > }; > > > > > static ssize_t show_node_state(struct device *dev, > @@ -1024,23 +1026,57 @@ static ssize_t show_node_state(struct device *dev, > nodemask_pr_args(&node_states[na->state])); > } > > > > > -#define _NODE_ATTR(name, state) \ > - { __ATTR(name, 0444, show_node_state, NULL), state } > +static ssize_t store_node_state(struct device *s, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + nodemask_t nodes; > + struct node_attr *na = container_of(attr, struct node_attr, attr); > + > + if (nodelist_parse(buf, nodes)) > + return -EINVAL; > + > + if (na->write) { > + if (na->write(nodes)) > + return -EINVAL; > + } else { > + node_states[na->state] = nodes; > + } > + > + return count; > +} > + > +static int demotion_targets_write(nodemask_t nodes) > +{ > + if (nodes_subset(nodes, node_states[N_MEMORY])) { > + node_states[N_DEMOTION_TARGETS] = nodes; > + set_migration_target_nodes(); > + return 0; > + } > + > + return -EINVAL; > +} > + > +#define _NODE_ATTR_RO(name, state) \ > + { __ATTR(name, 0444, show_node_state, NULL), state, NULL } > + > +#define _NODE_ATTR_RW(name, state, write_fn) \ > + { __ATTR(name, 0644, show_node_state, store_node_state), state, write_fn } > > > > > static struct node_attr node_state_attr[] = { > - [N_POSSIBLE] = _NODE_ATTR(possible, N_POSSIBLE), > - [N_ONLINE] = _NODE_ATTR(online, N_ONLINE), > - [N_NORMAL_MEMORY] = _NODE_ATTR(has_normal_memory, N_NORMAL_MEMORY), > + [N_POSSIBLE] = _NODE_ATTR_RO(possible, N_POSSIBLE), > + [N_ONLINE] = _NODE_ATTR_RO(online, N_ONLINE), > + [N_NORMAL_MEMORY] = _NODE_ATTR_RO(has_normal_memory, N_NORMAL_MEMORY), > #ifdef CONFIG_HIGHMEM > - [N_HIGH_MEMORY] = _NODE_ATTR(has_high_memory, N_HIGH_MEMORY), > + [N_HIGH_MEMORY] = _NODE_ATTR_RO(has_high_memory, N_HIGH_MEMORY), > #endif > - [N_MEMORY] = _NODE_ATTR(has_memory, N_MEMORY), > - [N_CPU] = _NODE_ATTR(has_cpu, N_CPU), > - [N_GENERIC_INITIATOR] = _NODE_ATTR(has_generic_initiator, > - N_GENERIC_INITIATOR), > - [N_DEMOTION_TARGETS] = _NODE_ATTR(demotion_targets, > - N_DEMOTION_TARGETS), > - > + [N_MEMORY] = _NODE_ATTR_RO(has_memory, N_MEMORY), > + [N_CPU] = _NODE_ATTR_RO(has_cpu, N_CPU), > + [N_GENERIC_INITIATOR] = _NODE_ATTR_RO(has_generic_initiator, > + N_GENERIC_INITIATOR), > + [N_DEMOTION_TARGETS] = _NODE_ATTR_RW(demotion_targets, > + N_DEMOTION_TARGETS, > + demotion_targets_write), > }; > > > > > static struct attribute *node_state_attrs[] = {
