From 087ff6a5ae3052bb2835e191094b793789cb8817 Mon Sep 17 00:00:00 2001 From: Tyrel Datwyler Date: Wed, 20 Sep 2017 17:02:51 -0400 Subject: [PATCH] powerpc/pseries: Fix "OF: ERROR: Bad of_node_put() on /cpus" during DLPAR Commit 215ee763f8cb ("powerpc: pseries: remove dlpar_attach_node dependency on full path") reworked dlpar_attach_node() to no longer look up the parent node "/cpus", but instead to have the parent node passed by the caller in the function parameter list. As a result dlpar_attach_node() is no longer responsible for freeing the reference to the parent node. However, commit 215ee763f8cb failed to remove the of_node_put(parent) call in dlpar_attach_node(), or to take into account that the reference to the parent in the caller dlpar_cpu_add() needs to be held until after dlpar_attach_node() returns. As a result doing repeated cpu add/remove dlpar operations will eventually result in the following error: OF: ERROR: Bad of_node_put() on /cpus CPU: 0 PID: 10896 Comm: drmgr Not tainted 4.13.0-autotest #1 Call Trace: dump_stack+0x15c/0x1f8 (unreliable) of_node_release+0x1a4/0x1c0 kobject_put+0x1a8/0x310 kobject_del+0xbc/0xf0 __of_detach_node_sysfs+0x144/0x210 of_detach_node+0xf0/0x180 dlpar_detach_node+0xc4/0x120 dlpar_cpu_remove+0x280/0x560 dlpar_cpu_release+0xbc/0x1b0 arch_cpu_release+0x6c/0xb0 cpu_release_store+0xa0/0x100 dev_attr_store+0x68/0xa0 sysfs_kf_write+0xa8/0xf0 kernfs_fop_write+0x2cc/0x400 __vfs_write+0x5c/0x340 vfs_write+0x1a8/0x3d0 SyS_write+0xa8/0x1a0 system_call+0x58/0x6c Fix the issue by removing the of_node_put(parent) call from dlpar_attach_node(), and ensuring that the reference to the parent node is properly held and released by the caller dlpar_cpu_add(). Fixes: 215ee763f8cb ("powerpc: pseries: remove dlpar_attach_node dependency on full path") Signed-off-by: Tyrel Datwyler Reported-by: Abdul Haleem [mpe: Add a comment in the code and frob the change log slightly] Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/pseries/dlpar.c | 1 - arch/powerpc/platforms/pseries/hotplug-cpu.c | 6 +++++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c index 783f36364690..e45b5f10645a 100644 --- a/arch/powerpc/platforms/pseries/dlpar.c +++ b/arch/powerpc/platforms/pseries/dlpar.c @@ -266,7 +266,6 @@ int dlpar_attach_node(struct device_node *dn, struct device_node *parent) return rc; } - of_node_put(dn->parent); return 0; } diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c index fc0d8f97c03a..fadb95efbb9e 100644 --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c @@ -462,15 +462,19 @@ static ssize_t dlpar_cpu_add(u32 drc_index) } dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent); - of_node_put(parent); if (!dn) { pr_warn("Failed call to configure-connector, drc index: %x\n", drc_index); dlpar_release_drc(drc_index); + of_node_put(parent); return -EINVAL; } rc = dlpar_attach_node(dn, parent); + + /* Regardless we are done with parent now */ + of_node_put(parent); + if (rc) { saved_rc = rc; pr_warn("Failed to attach node %s, rc: %d, drc index: %x\n", -- 2.20.1