Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1f859adb authored by Nathan Fontenot's avatar Nathan Fontenot Committed by Michael Ellerman
Browse files

powerpc/pseries: Verify CPU doesn't exist before adding 



When DLPAR adding a CPU we should verify that the CPU does not already
exist. Failure to do so can generate a kernel oops;

[    9.465585] kernel BUG at arch/powerpc/platforms/pseries/dlpar.c:382!
[    9.465796] Oops: Exception in kernel mode, sig: 5 [#1]

This oops can be generated by causing a probe to be performed on a cpu
by writing to the sysfs cpu probe file (/sys/devices/system/cpu/probe).
This patch adds a check for the existence of cpu prior to probing the cpu
so userspace doing the wrong thing won't trigger a BUG_ON().

Signed-off-by: default avatarNathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 4450022b

arch/powerpc/platforms/pseries/dlpar.c

+39 −4
Original line number Diff line number Diff line
@@ -381,6 +381,32 @@ static int dlpar_online_cpu(struct device_node *dn) 


}



static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)

{

	struct device_node *child = NULL;

	u32 my_drc_index;

	bool found;

	int rc;



	/* Assume cpu doesn't exist */

	found = false;



	for_each_child_of_node(parent, child) {

		rc = of_property_read_u32(child, "ibm,my-drc-index",

					  &my_drc_index);

		if (rc)

			continue;



		if (my_drc_index == drc_index) {

			of_node_put(child);

			found = true;

			break;

		}

	}



	return found;

}



static ssize_t dlpar_cpu_probe(const char *buf, size_t count)

{

	struct device_node *dn, *parent;
@@ -391,14 +417,23 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count) 
	if (rc)

		return -EINVAL;



	rc = dlpar_acquire_drc(drc_index);

	if (rc)

		return -EINVAL;



	parent = of_find_node_by_path("/cpus");

	if (!parent)

		return -ENODEV;



	if (dlpar_cpu_exists(parent, drc_index)) {

		of_node_put(parent);

		printk(KERN_WARNING "CPU with drc index %x already exists\n",

		       drc_index);

		return -EINVAL;

	}



	rc = dlpar_acquire_drc(drc_index);

	if (rc) {

		of_node_put(parent);

		return -EINVAL;

	}



	dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);

	of_node_put(parent);

	if (!dn) {