This commit provides a mechanism for the host drivers to advertise the
support for different beacon intervals among the respective interface
combinations in a group, through diff_beacon_int_gcd_min (u32).

Following sets the expectation for diff_beacon_int_gcd_min.

= 0 - all beacon intervals for different interfaces must be same.
> 0 - different beacon intervals must have a GCD that's at
      least as big as this value.

Signed-off-by: Purushottam Kushwaha <[email protected]>
---
 include/net/cfg80211.h       |  9 ++++++++-
 include/uapi/linux/nl80211.h |  8 ++++++--
 net/wireless/core.h          |  2 +-
 net/wireless/nl80211.c       | 13 ++++++++++---
 net/wireless/util.c          | 46 ++++++++++++++++++++++++++++++++++++++++++--
 5 files changed, 69 insertions(+), 9 deletions(-)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 9c23f4d3..c3dd46c 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -2939,6 +2939,11 @@ struct ieee80211_iface_limit {
  *     only in special cases.
  * @radar_detect_widths: bitmap of channel widths supported for radar detection
  * @radar_detect_regions: bitmap of regions supported for radar detection
+ * @diff_beacon_int_gcd_min: This interface combination supports different
+ *     beacon intervals.
+ *     = 0 - all beacon intervals for different interface must be same.
+ *     > 0 - different beacon intervals must have a GCD that's at
+ *     least as big as this value.
  *
  * With this structure the driver can describe which interface
  * combinations it supports concurrently.
@@ -2959,7 +2964,7 @@ struct ieee80211_iface_limit {
  *  };
  *
  *
- * 2. Allow #{AP, P2P-GO} <= 8, channels = 1, 8 total:
+ * 2. Allow #{AP, P2P-GO} <= 8, diff BI min gcd = 10, channels = 1, 8 total:
  *
  *  struct ieee80211_iface_limit limits2[] = {
  *     { .max = 8, .types = BIT(NL80211_IFTYPE_AP) |
@@ -2970,6 +2975,7 @@ struct ieee80211_iface_limit {
  *     .n_limits = ARRAY_SIZE(limits2),
  *     .max_interfaces = 8,
  *     .num_different_channels = 1,
+ *     .diff_beacon_int_gcd_min = 10,
  *  };
  *
  *
@@ -2997,6 +3003,7 @@ struct ieee80211_iface_combination {
        bool beacon_int_infra_match;
        u8 radar_detect_widths;
        u8 radar_detect_regions;
+       u32 diff_beacon_int_gcd_min;
 };
 
 struct ieee80211_txrx_stypes {
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 2206941..894d131 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -4203,6 +4203,9 @@ enum nl80211_iface_limit_attrs {
  *     of supported channel widths for radar detection.
  * @NL80211_IFACE_COMB_RADAR_DETECT_REGIONS: u32 attribute containing the 
bitmap
  *     of supported regulatory regions for radar detection.
+ * @NL80211_IFACE_COMB_DIFF_BI_GCD_MIN: u32 attribute specifying the minimum 
GCD
+ *     of different beacon intervals supported by all the interface 
combinations
+ *     in this group (if not present, all beacon interval must match).
  * @NUM_NL80211_IFACE_COMB: number of attributes
  * @MAX_NL80211_IFACE_COMB: highest attribute number
  *
@@ -4210,8 +4213,8 @@ enum nl80211_iface_limit_attrs {
  *     limits = [ #{STA} <= 1, #{AP} <= 1 ], matching BI, channels = 1, max = 2
  *     => allows an AP and a STA that must match BIs
  *
- *     numbers = [ #{AP, P2P-GO} <= 8 ], channels = 1, max = 8
- *     => allows 8 of AP/GO
+ *     numbers = [ #{AP, P2P-GO} <= 8 ], diff BI min gcd, channels = 1, max = 
8,
+ *     => allows 8 of AP/GO that can have BI gcd >= min gcd
  *
  *     numbers = [ #{STA} <= 2 ], channels = 2, max = 2
  *     => allows two STAs on different channels
@@ -4237,6 +4240,7 @@ enum nl80211_if_combination_attrs {
        NL80211_IFACE_COMB_NUM_CHANNELS,
        NL80211_IFACE_COMB_RADAR_DETECT_WIDTHS,
        NL80211_IFACE_COMB_RADAR_DETECT_REGIONS,
+       NL80211_IFACE_COMB_DIFF_BI_GCD_MIN,
 
        /* keep last */
        NUM_NL80211_IFACE_COMB,
diff --git a/net/wireless/core.h b/net/wireless/core.h
index eee9144..5fffe58 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -475,7 +475,7 @@ int ieee80211_get_ratemask(struct ieee80211_supported_band 
*sband,
                           u32 *mask);
 
 int cfg80211_validate_beacon_int(struct cfg80211_registered_device *rdev,
-                                u32 beacon_int);
+                                enum nl80211_iftype iftype, u32 beacon_int);
 
 void cfg80211_update_iface_num(struct cfg80211_registered_device *rdev,
                               enum nl80211_iftype iftype, int num);
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 4997857..c1741d9 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1020,6 +1020,10 @@ static int nl80211_put_iface_combinations(struct wiphy 
*wiphy,
                     nla_put_u32(msg, NL80211_IFACE_COMB_RADAR_DETECT_REGIONS,
                                c->radar_detect_regions)))
                        goto nla_put_failure;
+               if (c->diff_beacon_int_gcd_min &&
+                   nla_put_u32(msg, NL80211_IFACE_COMB_DIFF_BI_GCD_MIN,
+                               c->diff_beacon_int_gcd_min))
+                       goto nla_put_failure;
 
                nla_nest_end(msg, nl_combi);
        }
@@ -3433,7 +3437,8 @@ static int nl80211_start_ap(struct sk_buff *skb, struct 
genl_info *info)
        params.dtim_period =
                nla_get_u32(info->attrs[NL80211_ATTR_DTIM_PERIOD]);
 
-       err = cfg80211_validate_beacon_int(rdev, params.beacon_interval);
+       err = cfg80211_validate_beacon_int(rdev, dev->ieee80211_ptr->iftype,
+                                          params.beacon_interval);
        if (err)
                return err;
 
@@ -7768,7 +7773,8 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct 
genl_info *info)
                ibss.beacon_interval =
                        nla_get_u32(info->attrs[NL80211_ATTR_BEACON_INTERVAL]);
 
-       err = cfg80211_validate_beacon_int(rdev, ibss.beacon_interval);
+       err = cfg80211_validate_beacon_int(rdev, NL80211_IFTYPE_ADHOC,
+                                          ibss.beacon_interval);
        if (err)
                return err;
 
@@ -9245,7 +9251,8 @@ static int nl80211_join_mesh(struct sk_buff *skb, struct 
genl_info *info)
                setup.beacon_interval =
                        nla_get_u32(info->attrs[NL80211_ATTR_BEACON_INTERVAL]);
 
-               err = cfg80211_validate_beacon_int(rdev, setup.beacon_interval);
+               err = cfg80211_validate_beacon_int(rdev, 
NL80211_IFTYPE_MESH_POINT,
+                                                  setup.beacon_interval);
                if (err)
                        return err;
        }
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 0675f51..844f02a 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1553,20 +1553,62 @@ bool ieee80211_chandef_to_operating_class(struct 
cfg80211_chan_def *chandef,
 }
 EXPORT_SYMBOL(ieee80211_chandef_to_operating_class);
 
+struct diff_beacon_int {
+       u32 gcd;
+       bool valid;
+};
+
+static void
+cfg80211_validate_diff_beacon_int(const struct ieee80211_iface_combination *c,
+                                 void *data)
+{
+       struct diff_beacon_int *diff_bi = data;
+
+       if (c->diff_beacon_int_gcd_min &&
+           (diff_bi->gcd >= c->diff_beacon_int_gcd_min))
+               diff_bi->valid = true;
+}
+
 int cfg80211_validate_beacon_int(struct cfg80211_registered_device *rdev,
-                                u32 beacon_int)
+                                enum nl80211_iftype iftype, u32 beacon_int)
 {
        struct wireless_dev *wdev;
        int res = 0;
+       int iftype_num[NUM_NL80211_IFTYPES];
 
        if (beacon_int < 10 || beacon_int > 10000)
                return -EINVAL;
 
+       memset(iftype_num, 0, sizeof(iftype_num));
+       list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list) {
+               if (!wdev->beacon_interval)
+                       continue;
+               iftype_num[wdev->iftype]++;
+       }
+       iftype_num[iftype]++;
+
        list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list) {
                if (!wdev->beacon_interval)
                        continue;
                if (wdev->beacon_interval != beacon_int) {
-                       res = -EINVAL;
+                       struct diff_beacon_int diff_bi = {
+                               wdev->beacon_interval,
+                               false,
+                       };
+
+                       /* Get the GCD */
+                       while (beacon_int != 0) {
+                               u32 tmp_bi = beacon_int;
+                               beacon_int = diff_bi.gcd % beacon_int;
+                               diff_bi.gcd = tmp_bi;
+                       }
+
+                       res = cfg80211_iter_combinations(&rdev->wiphy, 0, 0, 
iftype_num,
+                                                        
cfg80211_validate_diff_beacon_int,
+                                                        &diff_bi);
+                       if (res)
+                               return res;
+                       res = (diff_bi.valid) ? 0 : -EINVAL;
                        break;
                }
        }
-- 
1.9.1

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