Re: [PATCH v3 03/19] x86/resctrl: Create helper for RMID allocation and mondata dir creation

Ilpo Järvinen
2023-03-21T11:05:43Z

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On Mon, 20 Mar 2023, James Morse wrote:

> RMID are allocated for each monitor or control group directory, because
> each of these needs its own RMID. For control groups,
> rdtgroup_mkdir_ctrl_mon() later goes on to allocate the CLOSID.
>
> MPAM's equivalent of RMID are not an independent number, so can't be
> allocated until the CLOSID is known. An RMID allocation for one CLOSID
> may fail, whereas another may succeed depending on how many monitor
> groups a control group has.
>
> The RMID allocation needs to move to be after the CLOSID has been
> allocated.
>
> To make a subsequent change that does this easier to read, move the RMID
> allocation and mondata dir creation to a helper.
>
> Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 42 +++++++++++++++++---------
> 1 file changed, 27 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 6ecaf34a4e32..b785beb0db26 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -3135,6 +3135,30 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
> return 0;
> }
>
> +static int mkdir_rdt_prepare_rmid_alloc(struct rdtgroup *rdtgrp)
> +{
> + int ret;
> +
> + if (!rdt_mon_capable)
> + return 0;
> +
> + ret = alloc_rmid();
> + if (ret < 0) {
> + rdt_last_cmd_puts("Out of RMIDs\n");
> + return ret;
> + }
> + rdtgrp->mon.rmid = ret;
> +
> + ret = mkdir_mondata_all(rdtgrp->kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
> + if (ret) {
> + rdt_last_cmd_puts("kernfs subdir error\n");
> + free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
> const char *name, umode_t mode,
> enum rdt_group_type rtype, struct rdtgroup **r)
> @@ -3200,20 +3224,10 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
> goto out_destroy;
> }
>
> - if (rdt_mon_capable) {
> - ret = alloc_rmid();
> - if (ret < 0) {
> - rdt_last_cmd_puts("Out of RMIDs\n");
> - goto out_destroy;
> - }
> - rdtgrp->mon.rmid = ret;
> + ret = mkdir_rdt_prepare_rmid_alloc(rdtgrp);
> + if (ret)
> + goto out_destroy;
>
> - ret = mkdir_mondata_all(kn, rdtgrp, &rdtgrp->mon.mon_data_kn);
> - if (ret) {
> - rdt_last_cmd_puts("kernfs subdir error\n");
> - goto out_idfree;
> - }
> - }
> kernfs_activate(kn);
>
> /*
> @@ -3221,8 +3235,6 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
> */
> return 0;
>
> -out_idfree:
> - free_rmid(rdtgrp->closid, rdtgrp->mon.rmid);
> out_destroy:
> kernfs_put(rdtgrp->kn);
> kernfs_remove(rdtgrp->kn);
>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

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