[PATCH] x86/resctrl: Fix potential lockdep warning

[Xiaochen Shen <xiaochen.shen@intel.com>]

rdtgroup_cpus_write() and mkdir_rdt_prepare() call
rdtgroup_kn_lock_live() -> kernfs_to_rdtgroup() to get 'rdtgrp', and
then call rdt_last_cmd_xxx() functions which will check if
rdtgroup_mutex is held/requires its caller to hold rdtgroup_mutex.
But if 'rdtgrp' returned from kernfs_to_rdtgroup() is NULL,
rdtgroup_mutex is not held and calling rdt_last_cmd_xxx() will result
in a lockdep warning.

Remove rdt_last_cmd_xxx() in these two paths. Just returning error
should be sufficient to report to the user that the entry doesn't exist
any more.

Fixes: 94457b36e8a5 ("x86/intel_rdt: Add diagnostics when writing the cpus file")
Fixes: cfd0f34e4cd5 ("x86/intel_rdt: Add diagnostics when making directories")
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index a46dee8e78db..2e3b06d6bbc6 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -461,10 +461,8 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
 	}
 
 	rdtgrp = rdtgroup_kn_lock_live(of->kn);
-	rdt_last_cmd_clear();
 	if (!rdtgrp) {
 		ret = -ENOENT;
-		rdt_last_cmd_puts("Directory was removed\n");
 		goto unlock;
 	}
 
@@ -2648,10 +2646,8 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 	int ret;
 
 	prdtgrp = rdtgroup_kn_lock_live(prgrp_kn);
-	rdt_last_cmd_clear();
 	if (!prdtgrp) {
 		ret = -ENODEV;
-		rdt_last_cmd_puts("Directory was removed\n");
 		goto out_unlock;
 	}
 
-- 
1.8.3.1