linux-kernel - [PATCH] fs/resctrl: Restore the missing rdt_last_cmd

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Message-ID: <20250529113353.3275066-1-zengheng4@huawei.com>
Date: Thu, 29 May 2025 19:33:53 +0800
From: Zeng Heng <zengheng4@...wei.com>
To: <Dave.Martin@....com>, <bp@...e.de>, <tony.luck@...el.com>,
	<reinette.chatre@...el.com>, <james.morse@....com>,
	<xiaochen.shen@...el.com>, <fenghua.yu@...el.com>
CC: <bobo.shaobowang@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] fs/resctrl: Restore the missing rdt_last_cmd_clear()

The fixes tag patch resolves the lockdep warning. However, directly
removing rdt_last_cmd_clear() would leave the last_cmd_status interface
with stale logs, which does not conform to the functional definition before
the fix. Therefore, the rdt_last_cmd_clear() operation is performed after
successfully acquiring the rdtgroup_mutex.

Fixes: c8eafe149530 ("x86/resctrl: Fix potential lockdep warning")
Signed-off-by: Zeng Heng <zengheng4@...wei.com>
---
 fs/resctrl/rdtgroup.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index cc37f58b47dd..4aae9eb74215 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -536,6 +536,8 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
 		goto unlock;
 	}
 
+	rdt_last_cmd_clear();
+
 	if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
 	    rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
 		ret = -EINVAL;
@@ -3481,6 +3483,8 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
 		goto out_unlock;
 	}
 
+	rdt_last_cmd_clear();
+
 	if (rtype == RDTMON_GROUP &&
 	    (prdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
 	     prdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)) {
-- 
2.25.1