Re: [PATCH 5/5] kernel handling of CPU DLPAR

[Nathan Fontenot]

Andrey Panin wrote:
> On 254, 09 11, 2009 at 04:15:33PM -0500, Nathan Fontenot wrote:
> > This adds the capability to DLPAR add and remove CPUs from the kernel. The
> > creates two new files /sys/devices/system/cpu/probe and
> > /sys/devices/system/cpu/release to handle the DLPAR addition and
> > removal of
> > CPUs respectively.
> >
> > CPU DLPAR add is accomplished by writing the drc-index of the CPU to the
> > probe file, and removal is done by writing the device-tree path of the cpu
> > to the release file.
> >
> > Signed-off-by: Nathan Fontenot <nfont@xxxxxxxxxxxxxx>
>
> > +static ssize_t cpu_probe_store(struct class *class, const char *buf,
> > +			       size_t count)
> > +{
> > +	struct device_node *dn;
> > +	u32 drc_index;
> > +	char *cpu_name;
> > +	int rc;
> > +
> > +	drc_index = simple_strtoull(buf, NULL, 0);
> > +	if (!drc_index)
> > +		return -EINVAL;
> > +
> > +	rc = acquire_drc(drc_index);
> > +	if (rc)
> > +		return rc;
> > +
> > +	dn = configure_connector(drc_index);
> > +	if (!dn) {
> > +		release_drc(drc_index);
> > +		return rc;
> > +	}
> > +
> > +	/* fixup dn name */
> > +	cpu_name = kzalloc(strlen(dn->full_name) + strlen("/cpus/") + 1,
> > +			   GFP_KERNEL);
>
> Unchecked memory allocation with immediate crash in case of failure.

Yep, thats a bad thing.  I'll fix this in an updated patch.  thanks.

-Nathan

> > +	sprintf(cpu_name, "/cpus/%s", dn->full_name);
> > +	kfree(dn->full_name);
> > +	dn->full_name = cpu_name;
> > +
> > +	rc = add_device_tree_nodes(dn);
> > +	if (rc)
> > +		release_drc(drc_index);
> > +
> > +	return rc ? rc : count;
> > +}
> > +
> > +static ssize_t cpu_release_store(struct class *class, const char *buf,
> > +				 size_t count)
> > +{
> > +	struct device_node *dn;
> > +	u32 *drc_index;
> > +	int rc;
> > +
> > +	dn = of_find_node_by_path(buf);
> > +	if (!dn)
> > +		return -EINVAL;
> > +
> > +	drc_index = (u32 *)of_get_property(dn, "ibm,my-drc-index", NULL);
> > +	if (!drc_index) {
> > +		of_node_put(dn);
> > +		return -EINVAL;
> > +	}
> > +
> > +	rc = release_drc(*drc_index);
> > +	if (rc) {
> > +		of_node_put(dn);
> > +		return rc;
> > +	}
> > +
> > +	rc = remove_device_tree_nodes(dn);
> > +	if (rc)
> > +		acquire_drc(*drc_index);
> > +
> > +	of_node_put(dn);
> > +	return rc? rc : count;
> > +}
> > +
> > static struct class_attribute class_attr_mem_release =
> > 			__ATTR(release, S_IWUSR, NULL, memory_release_store);
> > +static struct class_attribute class_attr_cpu_probe =
> > +			__ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
> > +static struct class_attribute class_attr_cpu_release =
> > +			__ATTR(release, S_IWUSR, NULL, cpu_release_store);
> >
> > static int pseries_dlpar_init(void)
> > {
> > @@ -576,6 +648,18 @@
> > 		printk(KERN_INFO "DLPAR: Could not create sysfs memory "
> > 		       "release file\n");
> >
> > +	rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
> > +			       &class_attr_cpu_probe.attr);
> > +	if (rc)
> > +		printk(KERN_INFO "DLPAR: Could not create sysfs cpu "
> > +		       "probe file\n");
> > +
> > +	rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
> > +			       &class_attr_cpu_release.attr);
> > +	if (rc)
> > +		printk(KERN_INFO "DLPAR: Could not create sysfs cpu "
> > +		       "release file\n");
> > +
> > 	return 0;
> > }
> > __initcall(pseries_dlpar_init);
> > --
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