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x86/resctrl: Apply READ_ONCE/WRITE_ONCE to task_struct.{rmid,closid}

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commit 6d3b47ddffed70006cf4ba360eef61e9ce097d8f upstream.

A CPU's current task can have its {closid, rmid} fields read locally
while they are being concurrently written to from another CPU.
This can happen anytime __resctrl_sched_in() races with either
__rdtgroup_move_task() or rdt_move_group_tasks().

Prevent load / store tearing for those accesses by giving them the
READ_ONCE() / WRITE_ONCE() treatment.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/9921fda88ad81afb9885b517fbe864a2bc7c35a9.1608243147.git.reinette.chatre@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Valentin Schneider
2020-12-17 14:31:21 -08:00
committed by Greg Kroah-Hartman
parent 7123a4337b
commit 9554af9801
2 changed files with 12 additions and 9 deletions
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10
arch/x86/kernel/cpu/resctrl/rdtgroup.c
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@@ -563,11 +563,11 @@ static int __rdtgroup_move_task(struct task_struct *tsk,
*/
if (rdtgrp->type == RDTCTRL_GROUP) {
tsk->closid = rdtgrp->closid;
tsk->rmid = rdtgrp->mon.rmid;
WRITE_ONCE(tsk->closid, rdtgrp->closid);
WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
} else if (rdtgrp->type == RDTMON_GROUP) {
if (rdtgrp->mon.parent->closid == tsk->closid) {
tsk->rmid = rdtgrp->mon.rmid;
WRITE_ONCE(tsk->rmid, rdtgrp->mon.rmid);
} else {
rdt_last_cmd_puts("Can't move task to different control group\n");
return -EINVAL;
@@ -2312,8 +2312,8 @@ static void rdt_move_group_tasks(struct rdtgroup *from, struct rdtgroup *to,
for_each_process_thread(p, t) {
if (!from || is_closid_match(t, from) ||
is_rmid_match(t, from)) {
t->closid = to->closid;
t->rmid = to->mon.rmid;
WRITE_ONCE(t->closid, to->closid);
WRITE_ONCE(t->rmid, to->mon.rmid);
/*
* Order the closid/rmid stores above before the loads