| Message ID | 1416483178-5528-1-git-send-email-jukka.rissanen@linux.intel.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Thu, 2014-11-20 at 13:32 +0200, Jukka Rissanen wrote: > - moved owner netlink port id from cfg80211_sched_scan_request to > rdev in order to avoid possible races How does that really help though? You're not really locking it anyway. I think you should consider keeping it inside the sched_scan_request, but maybe make that an __rcu pointer. Your patch also still has the problem I pointed out to you before - you can get the following sequence of events: start_sched_scan (owner=true) close socket - schedule worker start_sched_scan (from another socket, owner doesn't matter) run worker - cancels the new sched_scan You need to make sure the worker is flushed in start_sched_scan or so, which might require RTNL work there or something. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Johannes, On to, 2014-11-20 at 16:14 +0100, Johannes Berg wrote: > On Thu, 2014-11-20 at 13:32 +0200, Jukka Rissanen wrote: > > > - moved owner netlink port id from cfg80211_sched_scan_request to > > rdev in order to avoid possible races > > How does that really help though? You're not really locking it anyway. > > I think you should consider keeping it inside the sched_scan_request, > but maybe make that an __rcu pointer. > > Your patch also still has the problem I pointed out to you before - you > can get the following sequence of events: > > start_sched_scan (owner=true) > close socket - schedule worker > start_sched_scan (from another socket, owner doesn't matter) If I am reading the code correctly from nl80211.c:nl80211_start_sched_scan() this socket will get -EINPROGRESS. Only after the worker has finished and called __cfg80211_stop_sched_scan() will the other socket able to start a new scheduled scan. Or I might have just missed some important detail here :) > run worker - cancels the new sched_scan > > You need to make sure the worker is flushed in start_sched_scan or so, > which might require RTNL work there or something. > > johannes > Cheers, Jukka -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2014-11-21 at 10:00 +0200, Jukka Rissanen wrote: > > Your patch also still has the problem I pointed out to you before - you > > can get the following sequence of events: > > > > start_sched_scan (owner=true) > > close socket - schedule worker > > start_sched_scan (from another socket, owner doesn't matter) > > If I am reading the code correctly from > nl80211.c:nl80211_start_sched_scan() this socket will get -EINPROGRESS. > Only after the worker has finished and called > __cfg80211_stop_sched_scan() will the other socket able to start a new > scheduled scan. Or I might have just missed some important detail > here :) Oh, you're right, my mistake. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h index 185f9c7..5038240 100644 --- a/include/uapi/linux/nl80211.h +++ b/include/uapi/linux/nl80211.h @@ -1640,6 +1640,9 @@ enum nl80211_commands { * @NL80211_ATTR_SOCKET_OWNER: Flag attribute, if set during interface * creation then the new interface will be owned by the netlink socket * that created it and will be destroyed when the socket is closed. + * If set during scheduled scan start then the new scan req will be + * owned by the netlink socket that created it and the scheduled scan will + * be stopped when the socket is closed. * * @NL80211_ATTR_TDLS_INITIATOR: flag attribute indicating the current end is * the TDLS link initiator. diff --git a/net/wireless/core.c b/net/wireless/core.c index a4d2792..6fffcb3 100644 --- a/net/wireless/core.c +++ b/net/wireless/core.c @@ -320,6 +320,21 @@ static void cfg80211_destroy_iface_wk(struct work_struct *work) rtnl_unlock(); } +static void cfg80211_sched_scan_stop_wk(struct work_struct *work) +{ + struct cfg80211_registered_device *rdev; + + rdev = container_of(work, struct cfg80211_registered_device, + sched_scan_stop_wk); + + rtnl_lock(); + + if (rdev->sched_scan_req) + __cfg80211_stop_sched_scan(rdev, false); + + rtnl_unlock(); +} + /* exported functions */ struct wiphy *wiphy_new_nm(const struct cfg80211_ops *ops, int sizeof_priv, @@ -406,6 +421,7 @@ use_default_name: INIT_LIST_HEAD(&rdev->destroy_list); spin_lock_init(&rdev->destroy_list_lock); INIT_WORK(&rdev->destroy_work, cfg80211_destroy_iface_wk); + INIT_WORK(&rdev->sched_scan_stop_wk, cfg80211_sched_scan_stop_wk); #ifdef CONFIG_CFG80211_DEFAULT_PS rdev->wiphy.flags |= WIPHY_FLAG_PS_ON_BY_DEFAULT; @@ -760,6 +776,7 @@ void wiphy_unregister(struct wiphy *wiphy) flush_work(&rdev->event_work); cancel_delayed_work_sync(&rdev->dfs_update_channels_wk); flush_work(&rdev->destroy_work); + flush_work(&rdev->sched_scan_stop_wk); #ifdef CONFIG_PM if (rdev->wiphy.wowlan_config && rdev->ops->set_wakeup) diff --git a/net/wireless/core.h b/net/wireless/core.h index 61ee664..c27615e 100644 --- a/net/wireless/core.h +++ b/net/wireless/core.h @@ -67,6 +67,8 @@ struct cfg80211_registered_device { unsigned long suspend_at; struct work_struct scan_done_wk; struct work_struct sched_scan_results_wk; + struct work_struct sched_scan_stop_wk; + u32 sched_scan_owner_nlportid; struct genl_info *cur_cmd_info; diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index df447c0..9ed6a34 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -5955,6 +5955,9 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, err = rdev_sched_scan_start(rdev, dev, request); if (!err) { + if (info->attrs[NL80211_ATTR_SOCKET_OWNER]) + rdev->sched_scan_owner_nlportid = info->snd_portid; + rdev->sched_scan_req = request; nl80211_send_sched_scan(rdev, dev, NL80211_CMD_START_SCHED_SCAN); @@ -12127,6 +12130,11 @@ static int nl80211_netlink_notify(struct notifier_block * nb, list_for_each_entry_rcu(rdev, &cfg80211_rdev_list, list) { bool schedule_destroy_work = false; + bool schedule_scan_stop = false; + + if (rdev->sched_scan_req && notify->portid && + rdev->sched_scan_owner_nlportid == notify->portid) + schedule_scan_stop = true; list_for_each_entry_rcu(wdev, &rdev->wdev_list, list) { cfg80211_mlme_unregister_socket(wdev, notify->portid); @@ -12157,6 +12165,12 @@ static int nl80211_netlink_notify(struct notifier_block * nb, spin_unlock(&rdev->destroy_list_lock); schedule_work(&rdev->destroy_work); } + } else if (schedule_scan_stop) { + rdev->sched_scan_owner_nlportid = 0; + + if (rdev->ops->sched_scan_stop && + rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) + schedule_work(&rdev->sched_scan_stop_wk); } }
An attribute NL80211_ATTR_SOCKET_OWNER can be set by the scan initiator. If present, the attribute will cause the scan to be stopped if the client dies. Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com> --- Hi, v6: - moved owner netlink port id from cfg80211_sched_scan_request to rdev in order to avoid possible races v5: - discarded the locking changes in v4 - instead of trying to schedule sched_scan_stop worker from struct cfg80211_sched_scan_request, move the worker to wiphy as that makes it easier to manage the sched_scan_stop worker. There are also one scheduled scan / wiphy so it is also logical to do it like this. v4: - rtnl locking issues fixed in patch 2 v3: - backward compatibility define tweaked in patch 1 - added missing signed-off-by: v2: - split the patch - In patch 1, use a generic NL80211_ATTR_SOCKET_OWNER attribute and convert the old code that uses NL80211_ATTR_IFACE_SOCKET_OWNER to use the new value. A define is provided for backward compatibility. - Any pending schedule scan stop worker is cancelled when interface is taken down in patch 2 Cheers, Jukka include/uapi/linux/nl80211.h | 3 +++ net/wireless/core.c | 17 +++++++++++++++++ net/wireless/core.h | 2 ++ net/wireless/nl80211.c | 14 ++++++++++++++ 4 files changed, 36 insertions(+)