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

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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: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nathan Fontenot 2015-10-23 12:45:57 -05:00 committed by Michael Ellerman
parent 4450022b49
commit 1f859adb92
1 changed files with 39 additions and 4 deletions
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43
arch/powerpc/platforms/pseries/dlpar.c
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@ -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) {