[PATCH v06 1/9] hotplug/cpu: Conditionally acquire/release DRC index
Naveen N. Rao
naveen.n.rao at linux.vnet.ibm.com
Thu Jul 12 02:00:47 AEST 2018
Michael Bringmann wrote:
> powerpc/cpu: Modify dlpar_cpu_add and dlpar_cpu_remove to allow the
> skipping of DRC index acquire or release operations during the CPU
> add or remove operations. This is intended to support subsequent
> changes to provide a 'CPU readd' operation.
>
> Signed-off-by: Michael Bringmann <mwb at linux.vnet.ibm.com>
> ---
> Changes in patch:
> -- Move new validity check added to pseries_smp_notifier
> to another patch
> ---
> arch/powerpc/platforms/pseries/hotplug-cpu.c | 68 +++++++++++++++-----------
> 1 file changed, 39 insertions(+), 29 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
> index 6ef77ca..3632db2 100644
> --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
> @@ -432,7 +432,7 @@ static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
> return found;
> }
>
> -static ssize_t dlpar_cpu_add(u32 drc_index)
> +static ssize_t dlpar_cpu_add(u32 drc_index, bool acquire_drc)
> {
> struct device_node *dn, *parent;
> int rc, saved_rc;
> @@ -457,19 +457,22 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
> return -EINVAL;
> }
>
> - rc = dlpar_acquire_drc(drc_index);
> - if (rc) {
> - pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
> - rc, drc_index);
> - of_node_put(parent);
> - return -EINVAL;
> + if (acquire_drc) {
> + rc = dlpar_acquire_drc(drc_index);
> + if (rc) {
> + pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
> + rc, drc_index);
> + of_node_put(parent);
> + return -EINVAL;
> + }
> }
>
> dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);
> if (!dn) {
> pr_warn("Failed call to configure-connector, drc index: %x\n",
> drc_index);
> - dlpar_release_drc(drc_index);
> + if (acquire_drc)
> + dlpar_release_drc(drc_index);
> of_node_put(parent);
> return -EINVAL;
> }
> @@ -484,8 +487,9 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
> pr_warn("Failed to attach node %s, rc: %d, drc index: %x\n",
> dn->name, rc, drc_index);
>
> - rc = dlpar_release_drc(drc_index);
> - if (!rc)
> + if (acquire_drc)
> + rc = dlpar_release_drc(drc_index);
> + if (!rc || acquire_drc)
> dlpar_free_cc_nodes(dn);
(!rc) can only be true if acquire_drc is true, so we seem to be only
invoking dlpar_free_cc_nodes() if acquire_drc is true. Would it be
better to frame that condition in this manner:
if (acquire_drc) {
rc = dlpar_release_drc(drc_index):
if (!rc)
dlpar_free_cc_nodes(dn);
}
>
> return saved_rc;
> @@ -498,7 +502,7 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
> dn->name, rc, drc_index);
>
> rc = dlpar_detach_node(dn);
> - if (!rc)
> + if (!rc && acquire_drc)
> dlpar_release_drc(drc_index);
>
> return saved_rc;
> @@ -566,7 +570,8 @@ static int dlpar_offline_cpu(struct device_node *dn)
>
> }
>
> -static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
> +static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index,
> + bool release_drc)
> {
> int rc;
>
> @@ -579,12 +584,14 @@ static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
> return -EINVAL;
> }
>
> - rc = dlpar_release_drc(drc_index);
> - if (rc) {
> - pr_warn("Failed to release drc (%x) for CPU %s, rc: %d\n",
> - drc_index, dn->name, rc);
> - dlpar_online_cpu(dn);
> - return rc;
> + if (release_drc) {
> + rc = dlpar_release_drc(drc_index);
> + if (rc) {
> + pr_warn("Failed to release drc (%x) for CPU %s, rc: %d\n",
> + drc_index, dn->name, rc);
> + dlpar_online_cpu(dn);
> + return rc;
> + }
> }
>
> rc = dlpar_detach_node(dn);
> @@ -593,7 +600,10 @@ static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
>
> pr_warn("Failed to detach CPU %s, rc: %d", dn->name, rc);
>
> - rc = dlpar_acquire_drc(drc_index);
> + if (release_drc)
> + rc = dlpar_acquire_drc(drc_index);
> + else
> + rc = 0;
> if (!rc)
> dlpar_online_cpu(dn);
Here, we seem to want to invoke dlpar_online_cpu() unconditionally if
release_drc is false. So, to make that explicit, would it be better to
frame that as:
if (release_drc)
rc = dlpar_acquire_drc(drc_index);
if (!release_drc || !rc)
dlpar_online_cpu(dn);
- Naveen
>
> @@ -622,7 +632,7 @@ static struct device_node *cpu_drc_index_to_dn(u32 drc_index)
> return dn;
> }
>
> -static int dlpar_cpu_remove_by_index(u32 drc_index)
> +static int dlpar_cpu_remove_by_index(u32 drc_index, bool release_drc)
> {
> struct device_node *dn;
> int rc;
> @@ -634,7 +644,7 @@ static int dlpar_cpu_remove_by_index(u32 drc_index)
> return -ENODEV;
> }
>
> - rc = dlpar_cpu_remove(dn, drc_index);
> + rc = dlpar_cpu_remove(dn, drc_index, release_drc);
> of_node_put(dn);
> return rc;
> }
> @@ -699,7 +709,7 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
> }
>
> for (i = 0; i < cpus_to_remove; i++) {
> - rc = dlpar_cpu_remove_by_index(cpu_drcs[i]);
> + rc = dlpar_cpu_remove_by_index(cpu_drcs[i], true);
> if (rc)
> break;
>
> @@ -710,7 +720,7 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
> pr_warn("CPU hot-remove failed, adding back removed CPUs\n");
>
> for (i = 0; i < cpus_removed; i++)
> - dlpar_cpu_add(cpu_drcs[i]);
> + dlpar_cpu_add(cpu_drcs[i], true);
>
> rc = -EINVAL;
> } else {
> @@ -780,7 +790,7 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add)
> }
>
> for (i = 0; i < cpus_to_add; i++) {
> - rc = dlpar_cpu_add(cpu_drcs[i]);
> + rc = dlpar_cpu_add(cpu_drcs[i], true);
> if (rc)
> break;
>
> @@ -791,7 +801,7 @@ static int dlpar_cpu_add_by_count(u32 cpus_to_add)
> pr_warn("CPU hot-add failed, removing any added CPUs\n");
>
> for (i = 0; i < cpus_added; i++)
> - dlpar_cpu_remove_by_index(cpu_drcs[i]);
> + dlpar_cpu_remove_by_index(cpu_drcs[i], true);
>
> rc = -EINVAL;
> } else {
> @@ -817,7 +827,7 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
> if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
> rc = dlpar_cpu_remove_by_count(count);
> else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
> - rc = dlpar_cpu_remove_by_index(drc_index);
> + rc = dlpar_cpu_remove_by_index(drc_index, true);
> else
> rc = -EINVAL;
> break;
> @@ -825,7 +835,7 @@ int dlpar_cpu(struct pseries_hp_errorlog *hp_elog)
> if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
> rc = dlpar_cpu_add_by_count(count);
> else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
> - rc = dlpar_cpu_add(drc_index);
> + rc = dlpar_cpu_add(drc_index, true);
> else
> rc = -EINVAL;
> break;
> @@ -850,7 +860,7 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
> if (rc)
> return -EINVAL;
>
> - rc = dlpar_cpu_add(drc_index);
> + rc = dlpar_cpu_add(drc_index, true);
>
> return rc ? rc : count;
> }
> @@ -871,7 +881,7 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count)
> return -EINVAL;
> }
>
> - rc = dlpar_cpu_remove(dn, drc_index);
> + rc = dlpar_cpu_remove(dn, drc_index, true);
> of_node_put(dn);
>
> return rc ? rc : count;
>
>
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