Hello,

aahringo@redhat.com wrote on Sun, 17 Sep 2023 07:50:55 -0400:

Hi,

On Sat, Sep 16, 2023 at 11:39 AM Stefan Schmidt
[off-list ref] wrote:

quoted

Hello Miquel.

On 01.09.23 19:04, Miquel Raynal wrote:  

quoted

Introduce structures to describe peer devices in a PAN as well as a few
related helpers. We basically care about:
- Our unique parent after associating with a coordinator.
- Peer devices, children, which successfully associated with us.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
  include/net/cfg802154.h | 46 ++++++++++++++++++++++++++++
  net/ieee802154/Makefile |  2 +-
  net/ieee802154/core.c   |  2 ++
  net/ieee802154/pan.c    | 66 +++++++++++++++++++++++++++++++++++++++++
  4 files changed, 115 insertions(+), 1 deletion(-)
  create mode 100644 net/ieee802154/pan.c

diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
index f79ce133e51a..6c7193b4873c 100644
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h

@@ -303,6 +303,22 @@ struct ieee802154_coord_desc {
      bool gts_permit;
  };

+/**
+ * struct ieee802154_pan_device - PAN device information
+ * @pan_id: the PAN ID of this device
+ * @mode: the preferred mode to reach the device
+ * @short_addr: the short address of this device
+ * @extended_addr: the extended address of this device
+ * @node: the list node
+ */
+struct ieee802154_pan_device {
+     __le16 pan_id;
+     u8 mode;
+     __le16 short_addr;
+     __le64 extended_addr;
+     struct list_head node;
+};
+
  /**
   * struct cfg802154_scan_request - Scan request
   *

@@ -478,6 +494,11 @@ struct wpan_dev {

      /* fallback for acknowledgment bit setting */
      bool ackreq;
+
+     /* Associations */
+     struct mutex association_lock;
+     struct ieee802154_pan_device *parent;
+     struct list_head children;
  };

  #define to_phy(_dev)        container_of(_dev, struct wpan_phy, dev)

@@ -529,4 +550,29 @@ static inline const char *wpan_phy_name(struct wpan_phy *phy)
  void ieee802154_configure_durations(struct wpan_phy *phy,
                                  unsigned int page, unsigned int channel);

+/**
+ * cfg802154_device_is_associated - Checks whether we are associated to any device
+ * @wpan_dev: the wpan device  

Missing return value documentation.
 

quoted

+ */
+bool cfg802154_device_is_associated(struct wpan_dev *wpan_dev);
+
+/**
+ * cfg802154_device_is_parent - Checks if a device is our coordinator
+ * @wpan_dev: the wpan device
+ * @target: the expected parent
+ * @return: true if @target is our coordinator
+ */
+bool cfg802154_device_is_parent(struct wpan_dev *wpan_dev,
+                             struct ieee802154_addr *target);
+
+/**
+ * cfg802154_device_is_child - Checks whether a device is associated to us
+ * @wpan_dev: the wpan device
+ * @target: the expected child
+ * @return: the PAN device
+ */
+struct ieee802154_pan_device *
+cfg802154_device_is_child(struct wpan_dev *wpan_dev,
+                       struct ieee802154_addr *target);
+
  #endif /* __NET_CFG802154_H */

diff --git a/net/ieee802154/Makefile b/net/ieee802154/Makefile
index f05b7bdae2aa..7bce67673e83 100644
--- a/net/ieee802154/Makefile
+++ b/net/ieee802154/Makefile

@@ -4,7 +4,7 @@ obj-$(CONFIG_IEEE802154_SOCKET) += ieee802154_socket.o
  obj-y += 6lowpan/

  ieee802154-y := netlink.o nl-mac.o nl-phy.o nl_policy.o core.o \
-                header_ops.o sysfs.o nl802154.o trace.o
+                header_ops.o sysfs.o nl802154.o trace.o pan.o
  ieee802154_socket-y := socket.o

  CFLAGS_trace.o := -I$(src)

diff --git a/net/ieee802154/core.c b/net/ieee802154/core.c
index 57546e07e06a..cd69bdbfd59f 100644
--- a/net/ieee802154/core.c
+++ b/net/ieee802154/core.c

@@ -276,6 +276,8 @@ static int cfg802154_netdev_notifier_call(struct notifier_block *nb,
              wpan_dev->identifier = ++rdev->wpan_dev_id;
              list_add_rcu(&wpan_dev->list, &rdev->wpan_dev_list);
              rdev->devlist_generation++;
+             mutex_init(&wpan_dev->association_lock);
+             INIT_LIST_HEAD(&wpan_dev->children);

              wpan_dev->netdev = dev;
              break;

diff --git a/net/ieee802154/pan.c b/net/ieee802154/pan.c
new file mode 100644
index 000000000000..e2a12a42ba2b
--- /dev/null
+++ b/net/ieee802154/pan.c

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IEEE 802.15.4 PAN management
+ *
+ * Copyright (C) 2021 Qorvo US, Inc
+ * Authors:
+ *   - David Girault <david.girault@qorvo.com>
+ *   - Miquel Raynal <miquel.raynal@bootlin.com>
+ */
+
+#include <linux/kernel.h>
+#include <net/cfg802154.h>
+#include <net/af_ieee802154.h>
+
+static bool cfg802154_same_addr(struct ieee802154_pan_device *a,
+                             struct ieee802154_addr *b)
+{
+     if (!a || !b)
+             return false;
+
+     switch (b->mode) {
+     case IEEE802154_ADDR_SHORT:
+             return a->short_addr == b->short_addr;
+     case IEEE802154_ADDR_LONG:
+             return a->extended_addr == b->extended_addr;
+     default:
+             return false;
+     }
+}  

Don't we already have such a helper already?  

There must also be a check on (a->mode != b->mode) because short_addr
and extended_addr share memory in this struct.

True.

Actually the ieee802154_addr structure uses an enum to store either
the short address or the extended addres, while at the MAC level I'd
like to compare with what I call a ieee802154_pan_device: the PAN
device is part of a list defining the associated neighbors and contains
both an extended address and a short address once associated.

I do not want to compare the PAN ID here and I do not need to compare
if the modes are different because the device the code is running on
is known to have both an extended address and a short address field
which have been initialized.

With all these constraints, I think it would require more code to
re-use that small function than just writing a slightly different one
here which fully covers the "under association/disassociation" case, no?

We have something "similar" [0] to this with also checks on panid,
however it depends what Miquel tries to do here. I can imagine that we
extend the helper with an enum opt about what to compare.

- Alex

[0]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/net/ieee802154_netdev.h?h=v6.6-rc1#n232

Thanks for the link!

Thanks,
Miquèl