Messages in this thread Patch in this message |  | | From | Valentin Schneider <> | Subject | [PATCH v2 1/3] x86/intel_rdt: Check monitor group vs control group membership earlier | Date | Mon, 23 Nov 2020 02:24:31 +0000 |
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A task can only be moved between monitor groups if both groups belong to the same control group. This is checked fairly late however: by that time we already have appended a task_work() callback, the execution of which will be useless (there are no closid/rmid updates to handle, barring concurrent writes).
Check the validity of the move earlier to save any kzalloc() / task_work_add() if it wasn't going to be necessary.
Reviewed-by: James Morse <James.Morse@arm.com> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> --- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index af323e2e3100..b6b5b95df833 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -581,12 +581,7 @@ 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) { - tsk->rmid = rdtgrp->mon.rmid; - } else { - rdt_last_cmd_puts("Can't move task to different control group\n"); - ret = -EINVAL; - } + tsk->rmid = rdtgrp->mon.rmid; } } return ret; @@ -673,9 +668,19 @@ static int rdtgroup_move_task(pid_t pid, struct rdtgroup *rdtgrp, rcu_read_unlock(); ret = rdtgroup_task_write_permission(tsk, of); - if (!ret) - ret = __rdtgroup_move_task(tsk, rdtgrp); + if (ret) + goto out; + if (rdtgrp->type == RDTMON_GROUP && + rdtgrp->mon.parent->closid != tsk->closid) { + rdt_last_cmd_puts("Can't move task to different control group\n"); + ret = -EINVAL; + goto out; + } + + ret = __rdtgroup_move_task(tsk, rdtgrp); + +out: put_task_struct(tsk); return ret; } -- 2.27.0
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