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fs/resctrl: Restore the rdt_last_cmd_clear() calls after acquiring rdtgroup_mutex 

A lockdep fix removed two rdt_last_cmd_clear() calls that were used to
clear the last_cmd_status buffer but called without holding the required
rdtgroup_mutex.

The impacted resctrl commands are writing to the cpus or cpus_list files
and creating a new monitor or control group. With stale data in the
last_cmd_status buffer the impacted resctrl commands report the stale error
on success, or append its own failure message to the stale error on
failure.

Consequently, restore the rdt_last_cmd_clear() calls after acquiring
rdtgroup_mutex.

Fixes: c8eafe1495 ("x86/resctrl: Fix potential lockdep warning")
Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/all/20250603125828.1590067-1-zengheng4@huawei.com
pull/1212/merge
Zeng Heng 2025-06-03 20:58:28 +08:00 committed by Thomas Gleixner
parent 8b68e97871
commit dd2922dcfa
1 changed files with 4 additions and 0 deletions
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4
fs/resctrl/rdtgroup.c
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@ -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;
@ -3472,6 +3474,8 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
goto out_unlock;
}
rdt_last_cmd_clear();
/*
* Check that the parent directory for a monitor group is a "mon_groups"
* directory.