linux/net/mac802154/scan.c
Joel Fernandes (Google) eb56a4cbc3 mac802154: Rename kfree_rcu() to kvfree_rcu_mightsleep()
The k[v]free_rcu() macro's single-argument form is deprecated.
Therefore switch to the new k[v]free_rcu_mightsleep() variant. The goal
is to avoid accidental use of the single-argument forms, which can
introduce functionality bugs in atomic contexts and latency bugs in
non-atomic contexts.

The callers are holding a mutex so the context allows blocking. Hence
using the API with a single argument will be fine, but use its new name.

There is no functionality change with this patch.

Fixes: 57588c7117 ("mac802154: Handle passive scanning")
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
2023-04-05 13:48:04 +00:00

457 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* IEEE 802.15.4 scanning management
*
* Copyright (C) 2021 Qorvo US, Inc
* Authors:
* - David Girault <david.girault@qorvo.com>
* - Miquel Raynal <miquel.raynal@bootlin.com>
*/
#include <linux/module.h>
#include <linux/rtnetlink.h>
#include <net/mac802154.h>
#include "ieee802154_i.h"
#include "driver-ops.h"
#include "../ieee802154/nl802154.h"
#define IEEE802154_BEACON_MHR_SZ 13
#define IEEE802154_BEACON_PL_SZ 4
#define IEEE802154_BEACON_SKB_SZ (IEEE802154_BEACON_MHR_SZ + \
IEEE802154_BEACON_PL_SZ)
/* mac802154_scan_cleanup_locked() must be called upon scan completion or abort.
* - Completions are asynchronous, not locked by the rtnl and decided by the
* scan worker.
* - Aborts are decided by userspace, and locked by the rtnl.
*
* Concurrent modifications to the PHY, the interfaces or the hardware is in
* general prevented by the rtnl. So in most cases we don't need additional
* protection.
*
* However, the scan worker get's triggered without anybody noticing and thus we
* must ensure the presence of the devices as well as data consistency:
* - The sub-interface and device driver module get both their reference
* counters incremented whenever we start a scan, so they cannot disappear
* during operation.
* - Data consistency is achieved by the use of rcu protected pointers.
*/
static int mac802154_scan_cleanup_locked(struct ieee802154_local *local,
struct ieee802154_sub_if_data *sdata,
bool aborted)
{
struct wpan_dev *wpan_dev = &sdata->wpan_dev;
struct wpan_phy *wpan_phy = local->phy;
struct cfg802154_scan_request *request;
u8 arg;
/* Prevent any further use of the scan request */
clear_bit(IEEE802154_IS_SCANNING, &local->ongoing);
cancel_delayed_work(&local->scan_work);
request = rcu_replace_pointer(local->scan_req, NULL, 1);
if (!request)
return 0;
kvfree_rcu_mightsleep(request);
/* Advertize first, while we know the devices cannot be removed */
if (aborted)
arg = NL802154_SCAN_DONE_REASON_ABORTED;
else
arg = NL802154_SCAN_DONE_REASON_FINISHED;
nl802154_scan_done(wpan_phy, wpan_dev, arg);
/* Cleanup software stack */
ieee802154_mlme_op_post(local);
/* Set the hardware back in its original state */
drv_set_channel(local, wpan_phy->current_page,
wpan_phy->current_channel);
ieee802154_configure_durations(wpan_phy, wpan_phy->current_page,
wpan_phy->current_channel);
drv_stop(local);
synchronize_net();
sdata->required_filtering = sdata->iface_default_filtering;
drv_start(local, sdata->required_filtering, &local->addr_filt);
return 0;
}
int mac802154_abort_scan_locked(struct ieee802154_local *local,
struct ieee802154_sub_if_data *sdata)
{
ASSERT_RTNL();
if (!mac802154_is_scanning(local))
return -ESRCH;
return mac802154_scan_cleanup_locked(local, sdata, true);
}
static unsigned int mac802154_scan_get_channel_time(u8 duration_order,
u8 symbol_duration)
{
u64 base_super_frame_duration = (u64)symbol_duration *
IEEE802154_SUPERFRAME_PERIOD * IEEE802154_SLOT_PERIOD;
return usecs_to_jiffies(base_super_frame_duration *
(BIT(duration_order) + 1));
}
static void mac802154_flush_queued_beacons(struct ieee802154_local *local)
{
struct cfg802154_mac_pkt *mac_pkt, *tmp;
list_for_each_entry_safe(mac_pkt, tmp, &local->rx_beacon_list, node) {
list_del(&mac_pkt->node);
kfree_skb(mac_pkt->skb);
kfree(mac_pkt);
}
}
static void
mac802154_scan_get_next_channel(struct ieee802154_local *local,
struct cfg802154_scan_request *scan_req,
u8 *channel)
{
(*channel)++;
*channel = find_next_bit((const unsigned long *)&scan_req->channels,
IEEE802154_MAX_CHANNEL + 1,
*channel);
}
static int mac802154_scan_find_next_chan(struct ieee802154_local *local,
struct cfg802154_scan_request *scan_req,
u8 page, u8 *channel)
{
mac802154_scan_get_next_channel(local, scan_req, channel);
if (*channel > IEEE802154_MAX_CHANNEL)
return -EINVAL;
return 0;
}
void mac802154_scan_worker(struct work_struct *work)
{
struct ieee802154_local *local =
container_of(work, struct ieee802154_local, scan_work.work);
struct cfg802154_scan_request *scan_req;
struct ieee802154_sub_if_data *sdata;
unsigned int scan_duration = 0;
struct wpan_phy *wpan_phy;
u8 scan_req_duration;
u8 page, channel;
int ret;
/* Ensure the device receiver is turned off when changing channels
* because there is no atomic way to change the channel and know on
* which one a beacon might have been received.
*/
drv_stop(local);
synchronize_net();
mac802154_flush_queued_beacons(local);
rcu_read_lock();
scan_req = rcu_dereference(local->scan_req);
if (unlikely(!scan_req)) {
rcu_read_unlock();
return;
}
sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(scan_req->wpan_dev);
/* Wait an arbitrary amount of time in case we cannot use the device */
if (local->suspended || !ieee802154_sdata_running(sdata)) {
rcu_read_unlock();
queue_delayed_work(local->mac_wq, &local->scan_work,
msecs_to_jiffies(1000));
return;
}
wpan_phy = scan_req->wpan_phy;
scan_req_duration = scan_req->duration;
/* Look for the next valid chan */
page = local->scan_page;
channel = local->scan_channel;
do {
ret = mac802154_scan_find_next_chan(local, scan_req, page, &channel);
if (ret) {
rcu_read_unlock();
goto end_scan;
}
} while (!ieee802154_chan_is_valid(scan_req->wpan_phy, page, channel));
rcu_read_unlock();
/* Bypass the stack on purpose when changing the channel */
rtnl_lock();
ret = drv_set_channel(local, page, channel);
rtnl_unlock();
if (ret) {
dev_err(&sdata->dev->dev,
"Channel change failure during scan, aborting (%d)\n", ret);
goto end_scan;
}
local->scan_page = page;
local->scan_channel = channel;
rtnl_lock();
ret = drv_start(local, IEEE802154_FILTERING_3_SCAN, &local->addr_filt);
rtnl_unlock();
if (ret) {
dev_err(&sdata->dev->dev,
"Restarting failure after channel change, aborting (%d)\n", ret);
goto end_scan;
}
ieee802154_configure_durations(wpan_phy, page, channel);
scan_duration = mac802154_scan_get_channel_time(scan_req_duration,
wpan_phy->symbol_duration);
dev_dbg(&sdata->dev->dev,
"Scan page %u channel %u for %ums\n",
page, channel, jiffies_to_msecs(scan_duration));
queue_delayed_work(local->mac_wq, &local->scan_work, scan_duration);
return;
end_scan:
rtnl_lock();
mac802154_scan_cleanup_locked(local, sdata, false);
rtnl_unlock();
}
int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata,
struct cfg802154_scan_request *request)
{
struct ieee802154_local *local = sdata->local;
ASSERT_RTNL();
if (mac802154_is_scanning(local))
return -EBUSY;
/* TODO: support other scanning type */
if (request->type != NL802154_SCAN_PASSIVE)
return -EOPNOTSUPP;
/* Store scanning parameters */
rcu_assign_pointer(local->scan_req, request);
/* Software scanning requires to set promiscuous mode, so we need to
* pause the Tx queue during the entire operation.
*/
ieee802154_mlme_op_pre(local);
sdata->required_filtering = IEEE802154_FILTERING_3_SCAN;
local->scan_page = request->page;
local->scan_channel = -1;
set_bit(IEEE802154_IS_SCANNING, &local->ongoing);
nl802154_scan_started(request->wpan_phy, request->wpan_dev);
queue_delayed_work(local->mac_wq, &local->scan_work, 0);
return 0;
}
int mac802154_process_beacon(struct ieee802154_local *local,
struct sk_buff *skb,
u8 page, u8 channel)
{
struct ieee802154_beacon_hdr *bh = (void *)skb->data;
struct ieee802154_addr *src = &mac_cb(skb)->source;
struct cfg802154_scan_request *scan_req;
struct ieee802154_coord_desc desc;
if (skb->len != sizeof(*bh))
return -EINVAL;
if (unlikely(src->mode == IEEE802154_ADDR_NONE))
return -EINVAL;
dev_dbg(&skb->dev->dev,
"BEACON received on page %u channel %u\n",
page, channel);
memcpy(&desc.addr, src, sizeof(desc.addr));
desc.page = page;
desc.channel = channel;
desc.link_quality = mac_cb(skb)->lqi;
desc.superframe_spec = get_unaligned_le16(skb->data);
desc.gts_permit = bh->gts_permit;
trace_802154_scan_event(&desc);
rcu_read_lock();
scan_req = rcu_dereference(local->scan_req);
if (likely(scan_req))
nl802154_scan_event(scan_req->wpan_phy, scan_req->wpan_dev, &desc);
rcu_read_unlock();
return 0;
}
static int mac802154_transmit_beacon(struct ieee802154_local *local,
struct wpan_dev *wpan_dev)
{
struct cfg802154_beacon_request *beacon_req;
struct ieee802154_sub_if_data *sdata;
struct sk_buff *skb;
int ret;
/* Update the sequence number */
local->beacon.mhr.seq = atomic_inc_return(&wpan_dev->bsn) & 0xFF;
skb = alloc_skb(IEEE802154_BEACON_SKB_SZ, GFP_KERNEL);
if (!skb)
return -ENOBUFS;
rcu_read_lock();
beacon_req = rcu_dereference(local->beacon_req);
if (unlikely(!beacon_req)) {
rcu_read_unlock();
kfree_skb(skb);
return -EINVAL;
}
sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(beacon_req->wpan_dev);
skb->dev = sdata->dev;
rcu_read_unlock();
ret = ieee802154_beacon_push(skb, &local->beacon);
if (ret) {
kfree_skb(skb);
return ret;
}
/* Using the MLME transmission helper for sending beacons is a bit
* overkill because we do not really care about the final outcome.
*
* Even though, going through the whole net stack with a regular
* dev_queue_xmit() is not relevant either because we want beacons to be
* sent "now" rather than go through the whole net stack scheduling
* (qdisc & co).
*
* Finally, using ieee802154_subif_start_xmit() would only be an option
* if we had a generic transmit helper which would acquire the
* HARD_TX_LOCK() to prevent buffer handling conflicts with regular
* packets.
*
* So for now we keep it simple and send beacons with our MLME helper,
* even if it stops the ieee802154 queue entirely during these
* transmissions, wich anyway does not have a huge impact on the
* performances given the current design of the stack.
*/
return ieee802154_mlme_tx(local, sdata, skb);
}
void mac802154_beacon_worker(struct work_struct *work)
{
struct ieee802154_local *local =
container_of(work, struct ieee802154_local, beacon_work.work);
struct cfg802154_beacon_request *beacon_req;
struct ieee802154_sub_if_data *sdata;
struct wpan_dev *wpan_dev;
int ret;
rcu_read_lock();
beacon_req = rcu_dereference(local->beacon_req);
if (unlikely(!beacon_req)) {
rcu_read_unlock();
return;
}
sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(beacon_req->wpan_dev);
/* Wait an arbitrary amount of time in case we cannot use the device */
if (local->suspended || !ieee802154_sdata_running(sdata)) {
rcu_read_unlock();
queue_delayed_work(local->mac_wq, &local->beacon_work,
msecs_to_jiffies(1000));
return;
}
wpan_dev = beacon_req->wpan_dev;
rcu_read_unlock();
dev_dbg(&sdata->dev->dev, "Sending beacon\n");
ret = mac802154_transmit_beacon(local, wpan_dev);
if (ret)
dev_err(&sdata->dev->dev,
"Beacon could not be transmitted (%d)\n", ret);
queue_delayed_work(local->mac_wq, &local->beacon_work,
local->beacon_interval);
}
int mac802154_stop_beacons_locked(struct ieee802154_local *local,
struct ieee802154_sub_if_data *sdata)
{
struct wpan_dev *wpan_dev = &sdata->wpan_dev;
struct cfg802154_beacon_request *request;
ASSERT_RTNL();
if (!mac802154_is_beaconing(local))
return -ESRCH;
clear_bit(IEEE802154_IS_BEACONING, &local->ongoing);
cancel_delayed_work(&local->beacon_work);
request = rcu_replace_pointer(local->beacon_req, NULL, 1);
if (!request)
return 0;
kvfree_rcu_mightsleep(request);
nl802154_beaconing_done(wpan_dev);
return 0;
}
int mac802154_send_beacons_locked(struct ieee802154_sub_if_data *sdata,
struct cfg802154_beacon_request *request)
{
struct ieee802154_local *local = sdata->local;
ASSERT_RTNL();
if (mac802154_is_beaconing(local))
mac802154_stop_beacons_locked(local, sdata);
/* Store beaconing parameters */
rcu_assign_pointer(local->beacon_req, request);
set_bit(IEEE802154_IS_BEACONING, &local->ongoing);
memset(&local->beacon, 0, sizeof(local->beacon));
local->beacon.mhr.fc.type = IEEE802154_FC_TYPE_BEACON;
local->beacon.mhr.fc.security_enabled = 0;
local->beacon.mhr.fc.frame_pending = 0;
local->beacon.mhr.fc.ack_request = 0;
local->beacon.mhr.fc.intra_pan = 0;
local->beacon.mhr.fc.dest_addr_mode = IEEE802154_NO_ADDRESSING;
local->beacon.mhr.fc.version = IEEE802154_2003_STD;
local->beacon.mhr.fc.source_addr_mode = IEEE802154_EXTENDED_ADDRESSING;
atomic_set(&request->wpan_dev->bsn, -1);
local->beacon.mhr.source.mode = IEEE802154_ADDR_LONG;
local->beacon.mhr.source.pan_id = request->wpan_dev->pan_id;
local->beacon.mhr.source.extended_addr = request->wpan_dev->extended_addr;
local->beacon.mac_pl.beacon_order = request->interval;
local->beacon.mac_pl.superframe_order = request->interval;
local->beacon.mac_pl.final_cap_slot = 0xf;
local->beacon.mac_pl.battery_life_ext = 0;
/* TODO: Fill this field depending on the coordinator capacity */
local->beacon.mac_pl.pan_coordinator = 1;
local->beacon.mac_pl.assoc_permit = 1;
/* Start the beacon work */
local->beacon_interval =
mac802154_scan_get_channel_time(request->interval,
request->wpan_phy->symbol_duration);
queue_delayed_work(local->mac_wq, &local->beacon_work, 0);
return 0;
}