On Thu, 23 Jun 2022 21:19:32 -0700
Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> Reduce the complexity and the overhead of walking the topology to
> determine endpoint connectivity to root decoder interleave
> configurations.
>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Hi Dan,
A few minor comments inline around naming and also one query on why
the refactor or reap_ports is connected to the xarray change.
Thanks,
Jonathan
> ---
> drivers/cxl/acpi.c | 2 +-
> drivers/cxl/core/hdm.c | 6 ++-
> drivers/cxl/core/port.c | 88 ++++++++++++++++++-----------------------
> drivers/cxl/cxl.h | 12 +++---
> 4 files changed, 51 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 09fe92177d03..92ad1f359faf 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -197,7 +197,7 @@ static int add_host_bridge_uport(struct device *match, void *arg)
> if (!bridge)
> return 0;
>
> - dport = cxl_find_dport_by_dev(root_port, match);
> + dport = cxl_dport_load(root_port, match);
Load is kind of specific to the xarray. I'd be tempted to keep it to
original find naming.
> if (!dport) {
> dev_dbg(host, "host bridge expected and not found\n");
> return 0;
> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
> index c0164f9b2195..672bf3e97811 100644
> --- a/drivers/cxl/core/hdm.c
> +++ b/drivers/cxl/core/hdm.c
> @@ -50,8 +50,9 @@ static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
> int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
> {
> struct cxl_switch_decoder *cxlsd;
> - struct cxl_dport *dport;
> + struct cxl_dport *dport = NULL;
> int single_port_map[1];
> + unsigned long index;
>
> cxlsd = cxl_switch_decoder_alloc(port, 1);
> if (IS_ERR(cxlsd))
> @@ -59,7 +60,8 @@ int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
>
> device_lock_assert(&port->dev);
>
> - dport = list_first_entry(&port->dports, typeof(*dport), list);
> + xa_for_each(&port->dports, index, dport)
> + break;
> single_port_map[0] = dport->port_id;
>
> return add_hdm_decoder(port, &cxlsd->cxld, single_port_map);
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index ea3ab9baf232..d2f6898940fa 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -452,6 +452,7 @@ static void cxl_port_release(struct device *dev)
> xa_for_each(&port->endpoints, index, ep)
> cxl_ep_remove(port, ep);
> xa_destroy(&port->endpoints);
> + xa_destroy(&port->dports);
> ida_free(&cxl_port_ida, port->id);
> kfree(port);
> }
> @@ -566,7 +567,7 @@ static struct cxl_port *cxl_port_alloc(struct device *uport,
> port->component_reg_phys = component_reg_phys;
> ida_init(&port->decoder_ida);
> port->dpa_end = -1;
> - INIT_LIST_HEAD(&port->dports);
> + xa_init(&port->dports);
> xa_init(&port->endpoints);
>
> device_initialize(dev);
> @@ -696,17 +697,13 @@ static int match_root_child(struct device *dev, const void *match)
> return 0;
>
> port = to_cxl_port(dev);
> - device_lock(dev);
> - list_for_each_entry(dport, &port->dports, list) {
> - iter = match;
> - while (iter) {
> - if (iter == dport->dport)
> - goto out;
> - iter = iter->parent;
> - }
> + iter = match;
> + while (iter) {
> + dport = cxl_dport_load(port, iter);
> + if (dport)
> + break;
> + iter = iter->parent;
> }
> -out:
> - device_unlock(dev);
>
> return !!iter;
> }
> @@ -730,9 +727,10 @@ EXPORT_SYMBOL_NS_GPL(find_cxl_root, CXL);
> static struct cxl_dport *find_dport(struct cxl_port *port, int id)
> {
> struct cxl_dport *dport;
> + unsigned long index;
>
> device_lock_assert(&port->dev);
> - list_for_each_entry (dport, &port->dports, list)
> + xa_for_each(&port->dports, index, dport)
> if (dport->port_id == id)
> return dport;
> return NULL;
> @@ -741,18 +739,21 @@ static struct cxl_dport *find_dport(struct cxl_port *port, int id)
> static int add_dport(struct cxl_port *port, struct cxl_dport *new)
> {
> struct cxl_dport *dup;
> + int rc;
>
> device_lock_assert(&port->dev);
> dup = find_dport(port, new->port_id);
> - if (dup)
> + if (dup) {
> dev_err(&port->dev,
> "unable to add dport%d-%s non-unique port id (%s)\n",
> new->port_id, dev_name(new->dport),
> dev_name(dup->dport));
> - else
> - list_add_tail(&new->list, &port->dports);
> + rc = -EBUSY;
Direct return slightly simpler and reduce indent on next bit plus makes
this more obviously an 'error condition' by indenting it.
> + } else
> + rc = xa_insert(&port->dports, (unsigned long)new->dport, new,
> + GFP_KERNEL);
>
> - return dup ? -EEXIST : 0;
> + return rc;
> }
>
> /*
> @@ -779,10 +780,8 @@ static void cxl_dport_remove(void *data)
> struct cxl_dport *dport = data;
> struct cxl_port *port = dport->port;
>
> + xa_erase(&port->dports, (unsigned long) dport->dport);
> put_device(dport->dport);
> - cond_cxl_root_lock(port);
> - list_del(&dport->list);
> - cond_cxl_root_unlock(port);
> }
>
> static void cxl_dport_unlink(void *data)
> @@ -834,7 +833,6 @@ struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port,
> if (!dport)
> return ERR_PTR(-ENOMEM);
>
> - INIT_LIST_HEAD(&dport->list);
> dport->dport = dport_dev;
> dport->port_id = port_id;
> dport->component_reg_phys = component_reg_phys;
> @@ -925,7 +923,7 @@ static int match_port_by_dport(struct device *dev, const void *data)
> return 0;
>
> port = to_cxl_port(dev);
> - dport = cxl_find_dport_by_dev(port, ctx->dport_dev);
> + dport = cxl_dport_load(port, ctx->dport_dev);
> if (ctx->dport)
> *ctx->dport = dport;
> return dport != NULL;
> @@ -1025,19 +1023,27 @@ EXPORT_SYMBOL_NS_GPL(cxl_endpoint_autoremove, CXL);
> * for a port to be unregistered is when all memdevs beneath that port have gone
> * through ->remove(). This "bottom-up" removal selectively removes individual
> * child ports manually. This depends on devm_cxl_add_port() to not change is
> - * devm action registration order.
> + * devm action registration order, and for dports to have already been
> + * destroyed by reap_dports().
> */
> -static void delete_switch_port(struct cxl_port *port, struct list_head *dports)
> +static void delete_switch_port(struct cxl_port *port)
> +{
> + devm_release_action(port->dev.parent, cxl_unlink_uport, port);
> + devm_release_action(port->dev.parent, unregister_port, port);
> +}
> +
> +static void reap_dports(struct cxl_port *port)
> {
> - struct cxl_dport *dport, *_d;
> + struct cxl_dport *dport;
> + unsigned long index;
> +
> + device_lock_assert(&port->dev);
>
> - list_for_each_entry_safe(dport, _d, dports, list) {
> + xa_for_each(&port->dports, index, dport) {
> devm_release_action(&port->dev, cxl_dport_unlink, dport);
> devm_release_action(&port->dev, cxl_dport_remove, dport);
> devm_kfree(&port->dev, dport);
> }
> - devm_release_action(port->dev.parent, cxl_unlink_uport, port);
> - devm_release_action(port->dev.parent, unregister_port, port);
> }
>
> static struct cxl_ep *cxl_ep_load(struct cxl_port *port,
> @@ -1054,8 +1060,8 @@ static void cxl_detach_ep(void *data)
> for (iter = &cxlmd->dev; iter; iter = grandparent(iter)) {
> struct device *dport_dev = grandparent(iter);
> struct cxl_port *port, *parent_port;
> - LIST_HEAD(reap_dports);
> struct cxl_ep *ep;
> + bool died = false;
>
> if (!dport_dev)
> break;
> @@ -1095,15 +1101,16 @@ static void cxl_detach_ep(void *data)
> * enumerated port. Block new cxl_add_ep() and garbage
> * collect the port.
> */
> + died = true;
> port->dead = true;
> - list_splice_init(&port->dports, &reap_dports);
> + reap_dports(port);
I'm not immediately clear on why this refactor is tied up with moving
to the xarray. Perhaps a comment in the commit message to add
more detail around this?
> }
> device_unlock(&port->dev);
>
> - if (!list_empty(&reap_dports)) {
> + if (died) {
> dev_dbg(&cxlmd->dev, "delete %s\n",
> dev_name(&port->dev));
> - delete_switch_port(port, &reap_dports);
> + delete_switch_port(port);
> }
> put_device(&port->dev);
> device_unlock(&parent_port->dev);
> @@ -1282,23 +1289,6 @@ struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd,
> }
> EXPORT_SYMBOL_NS_GPL(cxl_mem_find_port, CXL);
>
> -struct cxl_dport *cxl_find_dport_by_dev(struct cxl_port *port,
> - const struct device *dev)
> -{
> - struct cxl_dport *dport;
> -
> - device_lock(&port->dev);
> - list_for_each_entry(dport, &port->dports, list)
> - if (dport->dport == dev) {
> - device_unlock(&port->dev);
> - return dport;
> - }
> -
> - device_unlock(&port->dev);
> - return NULL;
> -}
> -EXPORT_SYMBOL_NS_GPL(cxl_find_dport_by_dev, CXL);
> -
> static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
> struct cxl_port *port, int *target_map)
> {
> @@ -1309,7 +1299,7 @@ static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
>
> device_lock_assert(&port->dev);
>
> - if (list_empty(&port->dports))
> + if (xa_empty(&port->dports))
> return -EINVAL;
>
> write_seqlock(&cxlsd->target_lock);
