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fs/resctrl: Communicate resource group deleted error via last_cmd_status

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User space expects last_cmd_status to contain additional information if any
resctrl command fails.

A resctrl command may be blocked on the rdtgroup_mutex waiting for another
command to finish and find that once the mutex is available that the resource
group has since been deleted.

In this scenario the command will fail while last_cmd_status contains either
"ok" if the last_cmd_status buffer is empty or an outdated error from
a previous command failure if last_cmd_status buffer has content.

Include clearing of last_cmd_status buffer as part of rdtgroup_kn_lock_live()
that is used to obtain access and needed locking to a resource group before
attempting a command on the group.

With the last_cmd_status buffer ready, provide an appropriate message to user
space if the resource group has been deleted.

No last_cmd_status treatment is needed for the remaining failure of
rdtgroup_kn_lock_live() encountering a non-existent resource group since that
could only occur during an attempt to obtain a resource group lock on a file
in info/ which is an invalid usage.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://patch.msgid.link/9982141ec6f3ec18e0c53d7feabb19651583cf0e.1782857711.git.reinette.chatre@intel.com
This commit is contained in:
Reinette Chatre 2026-06-30 21:27:09 -07:00 committed by Borislav Petkov (AMD)
parent b37678cfe5
commit bb38d45719
3 changed files with 11 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/resctrl/ctrlmondata.c
View File

@ -317,7 +317,6 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {
@ -434,7 +433,6 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of,
}
} else if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
if (!rdtgrp->plr->d) {
rdt_last_cmd_clear();
rdt_last_cmd_puts("Cache domain offline\n");
ret = -ENODEV;
} else {
@ -475,7 +473,6 @@ ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {

2
fs/resctrl/monitor.c
View File

@ -1696,7 +1696,6 @@ int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file *s, voi
goto out_unlock;
}
rdt_last_cmd_clear();
if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
ret = -EINVAL;
@ -1836,7 +1835,6 @@ ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {

20
fs/resctrl/rdtgroup.c
View File

@ -359,7 +359,6 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
if (rdtgrp) {
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
if (!rdtgrp->plr->d) {
rdt_last_cmd_clear();
rdt_last_cmd_puts("Cache domain offline\n");
ret = -ENODEV;
} else {
@ -522,8 +521,6 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
goto out_unlock;
}
rdt_last_cmd_clear();
if (!buf) {
rdt_last_cmd_printf("%s: Invalid input\n",
is_cpu_list(of) ? "cpus_list" : "cpus");
@ -788,7 +785,6 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
rdt_last_cmd_clear();
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
@ -1529,7 +1525,6 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of,
return -ENOENT;
}
rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {
rdt_last_cmd_puts("mode: Invalid input\n");
@ -1666,7 +1661,6 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
if (!rdtgrp->plr->d) {
rdt_last_cmd_clear();
rdt_last_cmd_puts("Cache domain offline\n");
ret = -ENODEV;
} else {
@ -2726,10 +2720,20 @@ struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
cpus_read_lock();
mutex_lock(&rdtgroup_mutex);
rdt_last_cmd_clear();
/* Was this group deleted while we waited? */
if (rdtgrp->flags & RDT_DELETED)
if (rdtgrp->flags & RDT_DELETED) {
/*
* It is safe to dereference kn to obtain the resource group's
* name because one extra reference to kn is obtained
* during resource group creation that will be released by
* rdtgroup_remove() called by rdtgroup_kn_put().
*/
rdt_last_cmd_printf("Resource group %s deleted. No commands possible.\n",
rdt_kn_name(rdtgrp->kn));
return NULL;
}
return rdtgrp;
}
@ -3943,8 +3947,6 @@ 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.