powerpc/pseries: Verify CPU doesn't exist before adding
authorNathan Fontenot <nfont@linux.vnet.ibm.com>
Fri, 23 Oct 2015 17:45:57 +0000 (12:45 -0500)
committerMichael Ellerman <mpe@ellerman.id.au>
Thu, 17 Dec 2015 11:41:01 +0000 (22:41 +1100)
commit1f859adb9253c201079962582253236e9b2cc3ce
tree530f2fdf162205d654e5f7df1c3726fa9586b41d
parent4450022b4952ce67d2f3006b4c38e12a0f38cd77
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: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/platforms/pseries/dlpar.c