Add NL80211_ATTR_SCAN_FLAGS to nl80211's NL80211_CMD_TRIGGER_SCAN and
define a flag to indicate outbound traffic should abort a scan request.
This is implemented in mac80211 and can be used (e.g. by wpa_supplicant)
to cause low-priority scan requests to be aborted when traffic is present
(reducing tx latency).
Signed-off-by: [email protected]
Signed-off-by: [email protected]
---
include/linux/nl80211.h | 3 ++
include/net/cfg80211.h | 11 ++++++++++
net/mac80211/ieee80211_i.h | 6 +++++
net/mac80211/scan.c | 46 ++++++++++++++++++++++++++++++++++++++-----
net/wireless/nl80211.c | 6 +++++
5 files changed, 66 insertions(+), 6 deletions(-)
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 7ba71e4..b7b8ea0 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1014,6 +1014,8 @@ enum nl80211_commands {
* @%NL80211_ATTR_REKEY_DATA: nested attribute containing the information
* necessary for GTK rekeying in the device, see &enum nl80211_rekey_data.
*
+ * @NL80211_ATTR_SCAN_FLAGS: scan request control flags (u8)
+ *
* @NL80211_ATTR_MAX: highest attribute number currently defined
* @__NL80211_ATTR_AFTER_LAST: internal use
*/
@@ -1216,6 +1218,7 @@ enum nl80211_attrs {
NL80211_ATTR_MAX_NUM_SCHED_SCAN_SSIDS,
NL80211_ATTR_MAX_SCHED_SCAN_IE_LEN,
+ NL80211_ATTR_SCAN_FLAGS,
/* add attributes here, update the policy in nl80211.c */
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 930c783..fc46f81 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -769,6 +769,15 @@ struct cfg80211_ssid {
};
/**
+ * enum cfg80211_scan_flag - scan request control flags
+ *
+ * @CFG80211_SCAN__FLAG_TX_ABORT: abort scan on pending transmit
+ */
+enum cfg80211_scan_flags {
+ CFG80211_SCAN_FLAG_TX_ABORT = BIT(0),
+};
+
+/**
* struct cfg80211_scan_request - scan request description
*
* @ssids: SSIDs to scan for (active scan only)
@@ -777,6 +786,7 @@ struct cfg80211_ssid {
* @n_channels: total number of channels to scan
* @ie: optional information element(s) to add into Probe Request or %NULL
* @ie_len: length of ie in octets
+ * @flags: bit field of flags controlling operation
* @wiphy: the wiphy this was for
* @dev: the interface
* @aborted: (internal) scan request was notified as aborted
@@ -787,6 +797,7 @@ struct cfg80211_scan_request {
u32 n_channels;
const u8 *ie;
size_t ie_len;
+ u8 flags;
/* internal */
struct wiphy *wiphy;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index dda0d1a..f1eaab9 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -714,6 +714,10 @@ enum {
* about us leaving the channel and stop all associated STA interfaces
* @SCAN_ENTER_OPER_CHANNEL: Enter the operating channel again, notify the
* AP about us being back and restart all associated STA interfaces
+ * @SCAN_ABORT: Abnormally terminate the scan operation, set only when
+ * on the operating channel
+ * @SCAN_ENTER_OPER_CHANNEL_ABORT: Return to the operating channel then
+ * terminate the scan operation
*/
enum mac80211_scan_state {
SCAN_DECISION,
@@ -721,6 +725,8 @@ enum mac80211_scan_state {
SCAN_SEND_PROBE,
SCAN_LEAVE_OPER_CHANNEL,
SCAN_ENTER_OPER_CHANNEL,
+ SCAN_ABORT,
+ SCAN_ENTER_OPER_CHANNEL_ABORT,
};
struct ieee80211_local {
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 08a45ac..fc2179f 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -478,6 +478,7 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
unsigned long min_beacon_int = 0;
struct ieee80211_sub_if_data *sdata;
struct ieee80211_channel *next_chan;
+ enum mac80211_scan_state next_scan_state;
/*
* check if at least one STA interface is associated,
@@ -548,12 +549,36 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
usecs_to_jiffies(min_beacon_int * 1024) *
local->hw.conf.listen_interval);
- if (associated && ( !tx_empty || bad_latency ||
- listen_int_exceeded))
- local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
+
+ if (associated && !tx_empty) {
+ if (unlikely(local->scan_req->flags & CFG80211_SCAN_FLAG_TX_ABORT)) {
+ /*
+ * Scan request is marked to abort when there
+ * is outbound traffic. Mark state to return
+ * the operating channel and then abort. This
+ * happens as soon as possible.
+ */
+ next_scan_state = SCAN_ENTER_OPER_CHANNEL_ABORT;
+ } else
+ next_scan_state = SCAN_ENTER_OPER_CHANNEL;
+ } else if (associated && (bad_latency || listen_int_exceeded))
+ next_scan_state = SCAN_ENTER_OPER_CHANNEL;
else
- local->next_scan_state = SCAN_SET_CHANNEL;
+ next_scan_state = SCAN_SET_CHANNEL;
+ } else {
+ /*
+ * We're on the operating channel currently; let's
+ * leave that channel now to scan another one unless
+ * there is pending traffic and the scan request is
+ * marked to abort when this happens.
+ */
+ if (associated && !tx_empty &&
+ (local->scan_req->flags & CFG80211_SCAN_FLAG_TX_ABORT))
+ next_scan_state = SCAN_ABORT;
+ else
+ next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
}
+ local->next_scan_state = next_scan_state;
*next_delay = 0;
}
@@ -597,8 +622,13 @@ static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *loca
*/
ieee80211_offchannel_return(local, true, false);
- *next_delay = HZ / 5;
- local->next_scan_state = SCAN_DECISION;
+ if (local->next_scan_state == SCAN_ENTER_OPER_CHANNEL) {
+ *next_delay = HZ / 5;
+ local->next_scan_state = SCAN_DECISION;
+ } else {
+ *next_delay = 0;
+ local->next_scan_state = SCAN_ABORT;
+ }
}
static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
@@ -744,8 +774,12 @@ void ieee80211_scan_work(struct work_struct *work)
ieee80211_scan_state_leave_oper_channel(local, &next_delay);
break;
case SCAN_ENTER_OPER_CHANNEL:
+ case SCAN_ENTER_OPER_CHANNEL_ABORT:
ieee80211_scan_state_enter_oper_channel(local, &next_delay);
break;
+ case SCAN_ABORT:
+ aborted = true;
+ goto out_complete;
}
} while (next_delay == 0);
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 44a3fc2..81fa898 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -132,6 +132,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
[NL80211_ATTR_MGMT_SUBTYPE] = { .type = NLA_U8 },
[NL80211_ATTR_IE] = { .type = NLA_BINARY,
.len = IEEE80211_MAX_DATA_LEN },
+ [NL80211_ATTR_SCAN_FLAGS] = { .type = NLA_U8 },
[NL80211_ATTR_SCAN_FREQUENCIES] = { .type = NLA_NESTED },
[NL80211_ATTR_SCAN_SSIDS] = { .type = NLA_NESTED },
@@ -3450,6 +3451,9 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
request->ie_len);
}
+ if (info->attrs[NL80211_ATTR_SCAN_FLAGS])
+ request->flags = nla_get_u8(info->attrs[NL80211_ATTR_SCAN_FLAGS]);
+
request->dev = dev;
request->wiphy = &rdev->wiphy;
@@ -6137,6 +6141,8 @@ static int nl80211_add_scan_req(struct sk_buff *msg,
if (req->ie)
NLA_PUT(msg, NL80211_ATTR_IE, req->ie_len, req->ie);
+ NLA_PUT_U8(msg, NL80211_ATTR_SCAN_FLAGS, req->flags);
+
return 0;
nla_put_failure:
return -ENOBUFS;
--
1.7.3.1
Add NL80211_ATTR_SCAN_FLAGS to nl80211's NL80211_CMD_TRIGGER_SCAN and
define a flag to indicate outbound traffic should abort a scan request.
This is implemented in mac80211 and can be used (e.g. by wpa_supplicant)
to cause low-priority scan requests to be aborted when traffic is present
(reducing tx latency).
Signed-off-by: [email protected]
Signed-off-by: [email protected]
---
v2: Fix broken merge into wireless-testing
include/linux/nl80211.h | 3 +++
include/net/cfg80211.h | 11 +++++++++++
net/mac80211/ieee80211_i.h | 6 ++++++
net/mac80211/scan.c | 44 +++++++++++++++++++++++++++++++++++---------
net/wireless/nl80211.c | 6 ++++++
5 files changed, 61 insertions(+), 9 deletions(-)
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 7ba71e4..b7b8ea0 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1014,6 +1014,8 @@ enum nl80211_commands {
* @%NL80211_ATTR_REKEY_DATA: nested attribute containing the information
* necessary for GTK rekeying in the device, see &enum nl80211_rekey_data.
*
+ * @NL80211_ATTR_SCAN_FLAGS: scan request control flags (u8)
+ *
* @NL80211_ATTR_MAX: highest attribute number currently defined
* @__NL80211_ATTR_AFTER_LAST: internal use
*/
@@ -1216,6 +1218,7 @@ enum nl80211_attrs {
NL80211_ATTR_MAX_NUM_SCHED_SCAN_SSIDS,
NL80211_ATTR_MAX_SCHED_SCAN_IE_LEN,
+ NL80211_ATTR_SCAN_FLAGS,
/* add attributes here, update the policy in nl80211.c */
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 930c783..fc46f81 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -769,6 +769,15 @@ struct cfg80211_ssid {
};
/**
+ * enum cfg80211_scan_flag - scan request control flags
+ *
+ * @CFG80211_SCAN__FLAG_TX_ABORT: abort scan on pending transmit
+ */
+enum cfg80211_scan_flags {
+ CFG80211_SCAN_FLAG_TX_ABORT = BIT(0),
+};
+
+/**
* struct cfg80211_scan_request - scan request description
*
* @ssids: SSIDs to scan for (active scan only)
@@ -777,6 +786,7 @@ struct cfg80211_ssid {
* @n_channels: total number of channels to scan
* @ie: optional information element(s) to add into Probe Request or %NULL
* @ie_len: length of ie in octets
+ * @flags: bit field of flags controlling operation
* @wiphy: the wiphy this was for
* @dev: the interface
* @aborted: (internal) scan request was notified as aborted
@@ -787,6 +797,7 @@ struct cfg80211_scan_request {
u32 n_channels;
const u8 *ie;
size_t ie_len;
+ u8 flags;
/* internal */
struct wiphy *wiphy;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index dda0d1a..f1eaab9 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -714,6 +714,10 @@ enum {
* about us leaving the channel and stop all associated STA interfaces
* @SCAN_ENTER_OPER_CHANNEL: Enter the operating channel again, notify the
* AP about us being back and restart all associated STA interfaces
+ * @SCAN_ABORT: Abnormally terminate the scan operation, set only when
+ * on the operating channel
+ * @SCAN_ENTER_OPER_CHANNEL_ABORT: Return to the operating channel then
+ * terminate the scan operation
*/
enum mac80211_scan_state {
SCAN_DECISION,
@@ -721,6 +725,8 @@ enum mac80211_scan_state {
SCAN_SEND_PROBE,
SCAN_LEAVE_OPER_CHANNEL,
SCAN_ENTER_OPER_CHANNEL,
+ SCAN_ABORT,
+ SCAN_ENTER_OPER_CHANNEL_ABORT,
};
struct ieee80211_local {
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 08a45ac..cd269f5 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -478,6 +478,7 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
unsigned long min_beacon_int = 0;
struct ieee80211_sub_if_data *sdata;
struct ieee80211_channel *next_chan;
+ enum mac80211_scan_state next_scan_state;
/*
* check if at least one STA interface is associated,
@@ -511,15 +512,19 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
if (ieee80211_cfg_on_oper_channel(local)) {
/* We're currently on operating channel. */
- if (next_chan == local->oper_channel)
+ if (associated && !tx_empty &&
+ (local->scan_req->flags & CFG80211_SCAN_FLAG_TX_ABORT))
+ /* We have a pending xmit and scan should abort. */
+ next_scan_state = SCAN_ABORT;
+ else if (next_chan == local->oper_channel)
/* We don't need to move off of operating channel. */
- local->next_scan_state = SCAN_SET_CHANNEL;
+ next_scan_state = SCAN_SET_CHANNEL;
else
/*
* We do need to leave operating channel, as next
* scan is somewhere else.
*/
- local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
+ next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
} else {
/*
* we're currently scanning a different channel, let's
@@ -548,12 +553,24 @@ static void ieee80211_scan_state_decision(struct ieee80211_local *local,
usecs_to_jiffies(min_beacon_int * 1024) *
local->hw.conf.listen_interval);
- if (associated && ( !tx_empty || bad_latency ||
- listen_int_exceeded))
- local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
+
+ if (associated && !tx_empty) {
+ if (unlikely(local->scan_req->flags & CFG80211_SCAN_FLAG_TX_ABORT)) {
+ /*
+ * Scan request is marked to abort when there
+ * is outbound traffic. Mark state to return
+ * the operating channel and then abort. This
+ * happens as soon as possible.
+ */
+ next_scan_state = SCAN_ENTER_OPER_CHANNEL_ABORT;
+ } else
+ next_scan_state = SCAN_ENTER_OPER_CHANNEL;
+ } else if (associated && (bad_latency || listen_int_exceeded))
+ next_scan_state = SCAN_ENTER_OPER_CHANNEL;
else
- local->next_scan_state = SCAN_SET_CHANNEL;
+ next_scan_state = SCAN_SET_CHANNEL;
}
+ local->next_scan_state = next_scan_state;
*next_delay = 0;
}
@@ -597,8 +614,13 @@ static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *loca
*/
ieee80211_offchannel_return(local, true, false);
- *next_delay = HZ / 5;
- local->next_scan_state = SCAN_DECISION;
+ if (local->next_scan_state == SCAN_ENTER_OPER_CHANNEL) {
+ *next_delay = HZ / 5;
+ local->next_scan_state = SCAN_DECISION;
+ } else {
+ *next_delay = 0;
+ local->next_scan_state = SCAN_ABORT;
+ }
}
static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
@@ -744,8 +766,12 @@ void ieee80211_scan_work(struct work_struct *work)
ieee80211_scan_state_leave_oper_channel(local, &next_delay);
break;
case SCAN_ENTER_OPER_CHANNEL:
+ case SCAN_ENTER_OPER_CHANNEL_ABORT:
ieee80211_scan_state_enter_oper_channel(local, &next_delay);
break;
+ case SCAN_ABORT:
+ aborted = true;
+ goto out_complete;
}
} while (next_delay == 0);
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 44a3fc2..81fa898 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -132,6 +132,7 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
[NL80211_ATTR_MGMT_SUBTYPE] = { .type = NLA_U8 },
[NL80211_ATTR_IE] = { .type = NLA_BINARY,
.len = IEEE80211_MAX_DATA_LEN },
+ [NL80211_ATTR_SCAN_FLAGS] = { .type = NLA_U8 },
[NL80211_ATTR_SCAN_FREQUENCIES] = { .type = NLA_NESTED },
[NL80211_ATTR_SCAN_SSIDS] = { .type = NLA_NESTED },
@@ -3450,6 +3451,9 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
request->ie_len);
}
+ if (info->attrs[NL80211_ATTR_SCAN_FLAGS])
+ request->flags = nla_get_u8(info->attrs[NL80211_ATTR_SCAN_FLAGS]);
+
request->dev = dev;
request->wiphy = &rdev->wiphy;
@@ -6137,6 +6141,8 @@ static int nl80211_add_scan_req(struct sk_buff *msg,
if (req->ie)
NLA_PUT(msg, NL80211_ATTR_IE, req->ie_len, req->ie);
+ NLA_PUT_U8(msg, NL80211_ATTR_SCAN_FLAGS, req->flags);
+
return 0;
nla_put_failure:
return -ENOBUFS;
--
1.7.3.1
On Mon, 2011-05-23 at 14:34 -0700, Paul Stewart wrote:
> @@ -1014,6 +1014,8 @@ enum nl80211_commands {
> * @%NL80211_ATTR_REKEY_DATA: nested attribute containing the information
> * necessary for GTK rekeying in the device, see &enum nl80211_rekey_data.
> *
> + * @NL80211_ATTR_SCAN_FLAGS: scan request control flags (u8)
I think it should either be a u32 or a flag attribute. u8 is kinda
pointless for a flags attribute since it needs 4 bytes of space anyway.
> +++ b/include/net/cfg80211.h
> @@ -769,6 +769,15 @@ struct cfg80211_ssid {
> };
>
> /**
> + * enum cfg80211_scan_flag - scan request control flags
> + *
> + * @CFG80211_SCAN__FLAG_TX_ABORT: abort scan on pending transmit
> + */
> +enum cfg80211_scan_flags {
> + CFG80211_SCAN_FLAG_TX_ABORT = BIT(0),
> +};
Err, this needs to be in nl80211.h as well, no? How else would userspace
know what flags it can use?
Additionally, it would seem that there's a need to advertise what flags
are supported by a given driver.
Would you mind splitting into nl80211/mac80211 pieces?
Also -- maybe you should explain a bit more verbosely in the commit log
why this is a good idea? I'm not even sure how it really reduces TX
latency?
johannes