x86/intel_rdt: Add diagnostics when writing the tasks file

About the only tricky case is trying to move a task into a monitor
group that is a subdirectory of a different control group. But cover
the simple cases too.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vikas Shivappa <vikas.shivappa@intel.com>
Cc: Boris Petkov <bp@suse.de>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/f1841cce6a242aed37cb926dee8942727331bf78.1506382469.git.tony.luck@intel.com

diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
index f29b4c2..30aeb26 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
+++ b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
@@ -232,10 +232,8 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
        int closid, ret = 0;
 
        /* Valid input requires a trailing newline */
-       if (nbytes == 0 || buf[nbytes - 1] != '\n') {
-               seq_buf_puts(&last_cmd_status, "no trailing newline\n");
+       if (nbytes == 0 || buf[nbytes - 1] != '\n')
                return -EINVAL;
-       }
        buf[nbytes - 1] = '\0';
 
        rdtgrp = rdtgroup_kn_lock_live(of->kn);

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index 6810351..d39092e 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -478,6 +478,7 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
                 */
                atomic_dec(&rdtgrp->waitcount);
                kfree(callback);
+               rdt_last_cmd_puts("task exited\n");
        } else {
                /*
                 * For ctrl_mon groups move both closid and rmid.
@@ -488,10 +489,12 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
                        tsk->closid = rdtgrp->closid;
                        tsk->rmid = rdtgrp->mon.rmid;
                } else if (rdtgrp->type == RDTMON_GROUP) {
-                       if (rdtgrp->mon.parent->closid == tsk->closid)
+                       if (rdtgrp->mon.parent->closid == tsk->closid) {
                                tsk->rmid = rdtgrp->mon.rmid;
-                       else
+                       } else {
+                               rdt_last_cmd_puts("Can't move task to different control group\n");
                                ret = -EINVAL;
+                       }
                }
        }
        return ret;
@@ -510,8 +513,10 @@ static int rdtgroup_task_write_permission(struct task_struct *task,
         */
        if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
            !uid_eq(cred->euid, tcred->uid) &&
-           !uid_eq(cred->euid, tcred->suid))
+           !uid_eq(cred->euid, tcred->suid)) {
+               rdt_last_cmd_printf("No permission to move task %d\n", task->pid);
                ret = -EPERM;
+       }
 
        put_cred(tcred);
        return ret;
@@ -528,6 +533,7 @@ static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp,
                tsk = find_task_by_vpid(pid);
                if (!tsk) {
                        rcu_read_unlock();
+                       rdt_last_cmd_printf("No task %d\n", pid);
                        return -ESRCH;
                }
        } else {
@@ -555,6 +561,7 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
        if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
                return -EINVAL;
        rdtgrp = rdtgroup_kn_lock_live(of->kn);
+       rdt_last_cmd_clear();
 
        if (rdtgrp)
                ret = rdtgroup_move_task(pid, rdtgrp, of);