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[v2,2/5] mac80211_hwsim: add hashtable with mac address keys for faster lookup

Message ID 7f6aabdb-0689-44b2-95e4-49696d765d0f@MAIL2.uni-rostock.de (mailing list archive)
State Changes Requested
Delegated to: Johannes Berg
Headers show

Commit Message

Benjamin Beichler Nov. 21, 2017, 12:17 p.m. UTC
This patch adds a rhastable for mac address lookup of hwsim radios. This
especially improve the speed on reception of a netlink message with a new
frame. Although redundant, we keep holding a normal list for all radios,
since the rhashtable_walk interface adds a lot of overhead for iterating
over all radios and the doc of rhashtable recommend a redundant structure
for stable walks in such situations.

Since rhashtable is rcu protected we do not need a lock for delivering
frames and thus improving this scenario.

Signed-off-by: Benjamin Beichler <benjamin.beichler@uni-rostock.de>
---
 drivers/net/wireless/mac80211_hwsim.c | 56 +++++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 16 deletions(-)
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Patch

diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index d35dc6b2a733..48b9efed725e 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -32,6 +32,7 @@ 
 #include <net/genetlink.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
+#include <linux/rhashtable.h>
 #include "mac80211_hwsim.h"
 
 #define WARN_QUEUE 100
@@ -489,6 +490,7 @@  static const struct ieee80211_iface_combination hwsim_if_comb_p2p_dev[] = {
 
 static spinlock_t hwsim_radio_lock;
 static LIST_HEAD(hwsim_radios);
+static struct rhashtable hwsim_radios_rht;
 static spinlock_t hwsim_delete_lock;
 static LIST_HEAD(delete_radios);
 static int hwsim_radio_idx;
@@ -501,6 +503,7 @@  static struct platform_driver mac80211_hwsim_driver = {
 
 struct mac80211_hwsim_data {
 	struct list_head list;
+	struct rhash_head rht;
 	struct ieee80211_hw *hw;
 	struct device *dev;
 	struct ieee80211_supported_band bands[NUM_NL80211_BANDS];
@@ -575,6 +578,20 @@  struct mac80211_hwsim_data {
 	u64 tx_failed;
 };
 
+static u32 hwsim_table_hash(const void *addr, u32 len, u32 seed)
+{
+	/* Use last four bytes of hw addr as hash index */
+	return jhash_1word(*(u32 *)(addr + 2), seed);
+}
+
+static const struct rhashtable_params hwsim_rht_params = {
+	.nelem_hint = 2,
+	.automatic_shrinking = true,
+	.key_len = ETH_ALEN,
+	.key_offset = offsetof(struct mac80211_hwsim_data, addresses[1]),
+	.head_offset = offsetof(struct mac80211_hwsim_data, rht),
+	.hashfn = hwsim_table_hash,
+};
 
 struct hwsim_radiotap_hdr {
 	struct ieee80211_radiotap_header hdr;
@@ -2727,6 +2744,15 @@  static int mac80211_hwsim_new_radio(struct genl_info *info,
 			     CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
 
 	spin_lock_bh(&hwsim_radio_lock);
+	err = rhashtable_insert_fast(&hwsim_radios_rht, &data->rht,
+				     hwsim_rht_params);
+	if (err < 0) {
+		pr_debug("mac80211_hwsim: radio index %d already present\n",
+			 idx);
+		spin_unlock_bh(&hwsim_radio_lock);
+		goto failed_final_insert;
+	}
+
 	list_add_tail(&data->list, &hwsim_radios);
 	spin_unlock_bh(&hwsim_radio_lock);
 
@@ -2735,6 +2761,9 @@  static int mac80211_hwsim_new_radio(struct genl_info *info,
 
 	return idx;
 
+failed_final_insert:
+	debugfs_remove_recursive(data->debugfs);
+	ieee80211_unregister_hw(data->hw);
 failed_hw:
 	device_release_driver(data->dev);
 failed_bind:
@@ -2870,22 +2899,9 @@  static void hwsim_mon_setup(struct net_device *dev)
 
 static struct mac80211_hwsim_data *get_hwsim_data_ref_from_addr(const u8 *addr)
 {
-	struct mac80211_hwsim_data *data;
-	bool _found = false;
-
-	spin_lock_bh(&hwsim_radio_lock);
-	list_for_each_entry(data, &hwsim_radios, list) {
-		if (memcmp(data->addresses[1].addr, addr, ETH_ALEN) == 0) {
-			_found = true;
-			break;
-		}
-	}
-	spin_unlock_bh(&hwsim_radio_lock);
-
-	if (!_found)
-		return NULL;
-
-	return data;
+	return rhashtable_lookup_fast(&hwsim_radios_rht,
+				      addr,
+				      hwsim_rht_params);
 }
 
 static void hwsim_register_wmediumd(struct net *net, u32 portid)
@@ -3184,6 +3200,8 @@  static int hwsim_del_radio_nl(struct sk_buff *msg, struct genl_info *info)
 			continue;
 
 		list_del(&data->list);
+		rhashtable_remove_fast(&hwsim_radios_rht, &data->rht,
+				       hwsim_rht_params);
 		spin_unlock_bh(&hwsim_radio_lock);
 		mac80211_hwsim_del_radio(data, wiphy_name(data->hw->wiphy),
 					 info);
@@ -3343,6 +3361,8 @@  static void remove_user_radios(u32 portid)
 	list_for_each_entry_safe(entry, tmp, &hwsim_radios, list) {
 		if (entry->destroy_on_close && entry->portid == portid) {
 			list_del(&entry->list);
+			rhashtable_remove_fast(&hwsim_radios_rht, &entry->rht,
+					       hwsim_rht_params);
 
 			spin_lock_bh(&hwsim_delete_lock);
 			list_add(&entry->list, &delete_radios);
@@ -3423,6 +3443,8 @@  static void __net_exit hwsim_exit_net(struct net *net)
 			continue;
 
 		list_del(&data->list);
+		rhashtable_remove_fast(&hwsim_radios_rht, &data->rht,
+				       hwsim_rht_params);
 
 		spin_lock_bh(&hwsim_delete_lock);
 		list_add(&data->list, &delete_radios);
@@ -3461,6 +3483,7 @@  static int __init init_mac80211_hwsim(void)
 
 	spin_lock_init(&hwsim_radio_lock);
 	spin_lock_init(&hwsim_delete_lock);
+	rhashtable_init(&hwsim_radios_rht, &hwsim_rht_params);
 
 	err = register_pernet_device(&hwsim_net_ops);
 	if (err)
@@ -3613,6 +3636,7 @@  static void __exit exit_mac80211_hwsim(void)
 	}
 	spin_unlock_bh(&hwsim_delete_lock);
 
+	rhashtable_destroy(&hwsim_radios_rht);
 	unregister_netdev(hwsim_mon);
 	platform_driver_unregister(&mac80211_hwsim_driver);
 	unregister_pernet_device(&hwsim_net_ops);