2013-06-13 22:57:12

by Thomas Pedersen

[permalink] [raw]
Subject: [PATCH v3] mac80211: update mesh beacon on workqueue

Instead of updating the mesh beacon immediately when
requested (which would require the sdata_lock()), defer it
to the mac80211 workqueue.

Fixes yet another deadlock on calling sta_info_flush()
with the sdata_lock() held from ieee80211_stop_mesh(). We
could just drop the sdata_lock() around the
mesh_sta_cleanup() call, but this path is also taken from
several non-locked error paths.

Signed-off-by: Thomas Pedersen <[email protected]>

---
v3:

cast u32 as unsigned long endianess (Johannes)
clear mesh work flags on stop (Johannes)
test_and_clear_bit() returns a bool
{set,clear}_bit() takes the bit _number_

net/mac80211/ieee80211_i.h | 1 +
net/mac80211/mesh.c | 53 ++++++++++++++++++++++++++++++++++----------
net/mac80211/mesh.h | 2 ++
3 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 7a6f1a0..f79156d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -543,6 +543,7 @@ struct ieee80211_if_mesh {
struct timer_list mesh_path_root_timer;

unsigned long wrkq_flags;
+ unsigned long mbss_changed;

u8 mesh_id[IEEE80211_MAX_MESH_ID_LEN];
size_t mesh_id_len;
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 6c33af4..d5dea94 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -161,11 +161,8 @@ void mesh_sta_cleanup(struct sta_info *sta)
del_timer_sync(&sta->plink_timer);
}

- if (changed) {
- sdata_lock(sdata);
+ if (changed)
ieee80211_mbss_info_change_notify(sdata, changed);
- sdata_unlock(sdata);
- }
}

int mesh_rmc_init(struct ieee80211_sub_if_data *sdata)
@@ -719,14 +716,18 @@ ieee80211_mesh_rebuild_beacon(struct ieee80211_sub_if_data *sdata)
void ieee80211_mbss_info_change_notify(struct ieee80211_sub_if_data *sdata,
u32 changed)
{
- if (sdata->vif.bss_conf.enable_beacon &&
- (changed & (BSS_CHANGED_BEACON |
- BSS_CHANGED_HT |
- BSS_CHANGED_BASIC_RATES |
- BSS_CHANGED_BEACON_INT)))
- if (ieee80211_mesh_rebuild_beacon(sdata))
- return;
- ieee80211_bss_info_change_notify(sdata, changed);
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+ unsigned long bits = changed;
+ u32 bit;
+
+ if (!bits)
+ return;
+
+ /* if we race with running work, worst case this work becomes a noop */
+ for_each_set_bit(bit, &bits, sizeof(changed) * BITS_PER_BYTE)
+ set_bit(bit, &ifmsh->mbss_changed);
+ set_bit(MESH_WORK_MBSS_CHANGED, &ifmsh->wrkq_flags);
+ ieee80211_queue_work(&sdata->local->hw, &sdata->work);
}

int ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata)
@@ -799,6 +800,10 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
del_timer_sync(&sdata->u.mesh.mesh_path_root_timer);
del_timer_sync(&sdata->u.mesh.mesh_path_timer);

+ /* clear any mesh work (for next join) we may have accrued */
+ ifmsh->wrkq_flags = 0;
+ ifmsh->mbss_changed = 0;
+
local->fif_other_bss--;
atomic_dec(&local->iff_allmultis);
ieee80211_configure_filter(local);
@@ -965,6 +970,28 @@ out:
sdata_unlock(sdata);
}

+static void mesh_bss_info_changed(struct ieee80211_sub_if_data *sdata)
+{
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+ u32 bit, changed = 0;
+
+ for_each_set_bit(bit, &ifmsh->mbss_changed,
+ sizeof(changed) * BITS_PER_BYTE) {
+ clear_bit(bit, &ifmsh->mbss_changed);
+ changed |= BIT(bit);
+ }
+
+ if (sdata->vif.bss_conf.enable_beacon &&
+ (changed & (BSS_CHANGED_BEACON |
+ BSS_CHANGED_HT |
+ BSS_CHANGED_BASIC_RATES |
+ BSS_CHANGED_BEACON_INT)))
+ if (ieee80211_mesh_rebuild_beacon(sdata))
+ return;
+
+ ieee80211_bss_info_change_notify(sdata, changed);
+}
+
void ieee80211_mesh_work(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
@@ -995,6 +1022,8 @@ void ieee80211_mesh_work(struct ieee80211_sub_if_data *sdata)
if (test_and_clear_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags))
mesh_sync_adjust_tbtt(sdata);

+ if (test_and_clear_bit(MESH_WORK_MBSS_CHANGED, &ifmsh->wrkq_flags))
+ mesh_bss_info_changed(sdata);
out:
sdata_unlock(sdata);
}
diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h
index 01a28bc..53bd870 100644
--- a/net/mac80211/mesh.h
+++ b/net/mac80211/mesh.h
@@ -57,6 +57,7 @@ enum mesh_path_flags {
* grow
* @MESH_WORK_ROOT: the mesh root station needs to send a frame
* @MESH_WORK_DRIFT_ADJUST: time to compensate for clock drift relative to other
+ * @MESH_WORK_MBSS_CHANGED: rebuild beacon and notify driver of BSS changes
* mesh nodes
*/
enum mesh_deferred_task_flags {
@@ -65,6 +66,7 @@ enum mesh_deferred_task_flags {
MESH_WORK_GROW_MPP_TABLE,
MESH_WORK_ROOT,
MESH_WORK_DRIFT_ADJUST,
+ MESH_WORK_MBSS_CHANGED,
};

/**
--
1.7.10.4



2013-06-18 13:58:49

by Johannes Berg

[permalink] [raw]
Subject: Re: [PATCH v3] mac80211: update mesh beacon on workqueue

On Thu, 2013-06-13 at 15:54 -0700, Thomas Pedersen wrote:


> * @MESH_WORK_ROOT: the mesh root station needs to send a frame
> * @MESH_WORK_DRIFT_ADJUST: time to compensate for clock drift relative to other
> + * @MESH_WORK_MBSS_CHANGED: rebuild beacon and notify driver of BSS changes
> * mesh nodes

That seems to have gone wrong :)

I fixed it and applied this.

johannes