[PATCH] wireless/airo: cache wireless scans

Observed problems when multiple processes request scans and subsequently
scan results.  This causes a scan result request to hit card registers
before the scan is complete, returning an incomplete scan list and
possibly making the card very angry.  Instead, cache the results of a
wireless scan and serve result requests from the cache, rather than
hitting the hardware for them.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 172 insertions, 59 deletions

diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index 6f591abacfdc..108d9fed8f07 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -770,6 +770,11 @@ typedef struct {
 } BSSListRid;
 
 typedef struct {
+  BSSListRid bss;
+  struct list_head list;
+} BSSListElement;
+
+typedef struct {
   u8 rssipct;
   u8 rssidBm;
 } tdsRssiEntry;
@@ -1120,6 +1125,8 @@ static int decapsulate(struct airo_info *ai, MICBuffer *mic, etherHead *pPacket,
 static u8 airo_rssi_to_dbm (tdsRssiEntry *rssi_rid, u8 rssi);
 static u8 airo_dbm_to_pct (tdsRssiEntry *rssi_rid, u8 dbm);
 
+static void airo_networks_free(struct airo_info *ai);
+
 struct airo_info {
         struct net_device_stats stats;
         struct net_device             *dev;
@@ -1151,7 +1158,7 @@ struct airo_info {
 #define FLAG_COMMIT     13
 #define FLAG_RESET      14
 #define FLAG_FLASHING   15
-#define JOB_MASK        0x1ff0000
+#define JOB_MASK        0x2ff0000
 #define JOB_DIE         16
 #define JOB_XMIT        17
 #define JOB_XMIT11      18
@@ -1161,6 +1168,7 @@ struct airo_info {
 #define JOB_EVENT       22
 #define JOB_AUTOWEP     23
 #define JOB_WSTATS      24
+#define JOB_SCAN_RESULTS  25
         int (*bap_read)(struct airo_info*, u16 *pu16Dst, int bytelen,
                         int whichbap);
         unsigned short *flash;
@@ -1177,7 +1185,7 @@ struct airo_info {
         } xmit, xmit11;
         struct net_device *wifidev;
         struct iw_statistics    wstats;         // wireless stats
-        unsigned long           scan_timestamp; /* Time started to scan */
+        unsigned long           scan_timeout;   /* Time scan should be read */
         struct iw_spy_data      spy_data;
         struct iw_public_data   wireless_data;
         /* MIC stuff */
@@ -1199,6 +1207,10 @@ struct airo_info {
         APListRid               *APList;
 #define PCI_SHARED_LEN          2*MPI_MAX_FIDS*PKTSIZE+RIDSIZE
         char                    proc_name[IFNAMSIZ];
+
+        struct list_head network_list;
+        struct list_head network_free_list;
+        BSSListElement *networks;
 };
 
 static inline int bap_read(struct airo_info *ai, u16 *pu16Dst, int bytelen,
@@ -2381,6 +2393,8 @@ void stop_airo_card( struct net_device *dev, int freeres )
                         dev_kfree_skb(skb);
         }
 
+        airo_networks_free (ai);
+
         kfree(ai->flash);
         kfree(ai->rssi);
         kfree(ai->APList);
@@ -2687,6 +2701,42 @@ static int reset_card( struct net_device *dev , int lock) {
         return 0;
 }
 
+#define MAX_NETWORK_COUNT       64
+static int airo_networks_allocate(struct airo_info *ai)
+{
+        if (ai->networks)
+                return 0;
+
+        ai->networks =
+            kzalloc(MAX_NETWORK_COUNT * sizeof(BSSListElement),
+                    GFP_KERNEL);
+        if (!ai->networks) {
+                airo_print_warn(ai->dev->name, "Out of memory allocating beacons");
+                return -ENOMEM;
+        }
+
+        return 0;
+}
+
+static void airo_networks_free(struct airo_info *ai)
+{
+        if (!ai->networks)
+                return;
+        kfree(ai->networks);
+        ai->networks = NULL;
+}
+
+static void airo_networks_initialize(struct airo_info *ai)
+{
+        int i;
+
+        INIT_LIST_HEAD(&ai->network_free_list);
+        INIT_LIST_HEAD(&ai->network_list);
+        for (i = 0; i < MAX_NETWORK_COUNT; i++)
+                list_add_tail(&ai->networks[i].list,
+                              &ai->network_free_list);
+}
+
 static struct net_device *_init_airo_card( unsigned short irq, int port,
                                            int is_pcmcia, struct pci_dev *pci,
                                            struct device *dmdev )
@@ -2728,6 +2778,10 @@ static struct net_device *_init_airo_card( unsigned short irq, int port,
         if (rc)
                 goto err_out_thr;
 
+        if (airo_networks_allocate (ai))
+                goto err_out_unlink;
+        airo_networks_initialize (ai);
+
         /* The Airo-specific entries in the device structure. */
         if (test_bit(FLAG_MPI,&ai->flags)) {
                 skb_queue_head_init (&ai->txq);
@@ -2749,7 +2803,6 @@ static struct net_device *_init_airo_card( unsigned short irq, int port,
 
         SET_NETDEV_DEV(dev, dmdev);
 
-
         reset_card (dev, 1);
         msleep(400);
 
@@ -2892,6 +2945,65 @@ static void airo_send_event(struct net_device *dev) {
         wireless_send_event(dev, SIOCGIWAP, &wrqu, NULL);
 }
 
+static void airo_process_scan_results (struct airo_info *ai) {
+        union iwreq_data        wrqu;
+        BSSListRid BSSList;
+        int rc;
+        BSSListElement * loop_net;
+        BSSListElement * tmp_net;
+
+        /* Blow away current list of scan results */
+        list_for_each_entry_safe (loop_net, tmp_net, &ai->network_list, list) {
+                list_move_tail (&loop_net->list, &ai->network_free_list);
+                /* Don't blow away ->list, just BSS data */
+                memset (loop_net, 0, sizeof (loop_net->bss));
+        }
+
+        /* Try to read the first entry of the scan result */
+        rc = PC4500_readrid(ai, RID_BSSLISTFIRST, &BSSList, sizeof(BSSList), 0);
+        if((rc) || (BSSList.index == 0xffff)) {
+                /* No scan results */
+                goto out;
+        }
+
+        /* Read and parse all entries */
+        tmp_net = NULL;
+        while((!rc) && (BSSList.index != 0xffff)) {
+                /* Grab a network off the free list */
+                if (!list_empty(&ai->network_free_list)) {
+                        tmp_net = list_entry(ai->network_free_list.next,
+                                            BSSListElement, list);
+                        list_del(ai->network_free_list.next);
+                }
+
+                if (tmp_net != NULL) {
+                        memcpy(tmp_net, &BSSList, sizeof(tmp_net->bss));
+                        list_add_tail(&tmp_net->list, &ai->network_list);
+                        tmp_net = NULL;
+                }
+
+                /* Read next entry */
+                rc = PC4500_readrid(ai, RID_BSSLISTNEXT,
+                                    &BSSList, sizeof(BSSList), 0);
+        }
+
+out:
+        ai->scan_timeout = 0;
+        clear_bit(JOB_SCAN_RESULTS, &ai->flags);
+        up(&ai->sem);
+
+        /* Send an empty event to user space.
+         * We don't send the received data on
+         * the event because it would require
+         * us to do complex transcoding, and
+         * we want to minimise the work done in
+         * the irq handler. Use a request to
+         * extract the data - Jean II */
+        wrqu.data.length = 0;
+        wrqu.data.flags = 0;
+        wireless_send_event(ai->dev, SIOCGIWSCAN, &wrqu, NULL);
+}
+
 static int airo_thread(void *data) {
         struct net_device *dev = data;
         struct airo_info *ai = dev->priv;
@@ -2921,13 +3033,26 @@ static int airo_thread(void *data) {
                                 set_current_state(TASK_INTERRUPTIBLE);
                                 if (ai->flags & JOB_MASK)
                                         break;
-                                if (ai->expires) {
-                                        if (time_after_eq(jiffies,ai->expires)){
+                                if (ai->expires || ai->scan_timeout) {
+                                        if (ai->scan_timeout &&
+                                                        time_after_eq(jiffies,ai->scan_timeout)){
+                                                set_bit(JOB_SCAN_RESULTS,&ai->flags);
+                                                break;
+                                        } else if (ai->expires &&
+                                                        time_after_eq(jiffies,ai->expires)){
                                                 set_bit(JOB_AUTOWEP,&ai->flags);
                                                 break;
                                         }
                                         if (!signal_pending(current)) {
-                                                schedule_timeout(ai->expires - jiffies);
+                                                unsigned long wake_at;
+                                                if (!ai->expires || !ai->scan_timeout) {
+                                                        wake_at = max(ai->expires,
+                                                                ai->scan_timeout);
+                                                } else {
+                                                        wake_at = min(ai->expires,
+                                                                ai->scan_timeout);
+                                                }
+                                                schedule_timeout(wake_at - jiffies);
                                                 continue;
                                         }
                                 } else if (!signal_pending(current)) {
@@ -2970,6 +3095,10 @@ static int airo_thread(void *data) {
                         airo_send_event(dev);
                 else if (test_bit(JOB_AUTOWEP, &ai->flags))
                         timer_func(dev);
+                else if (test_bit(JOB_SCAN_RESULTS, &ai->flags))
+                        airo_process_scan_results(ai);
+                else  /* Shouldn't get here, but we make sure to unlock */
+                        up(&ai->sem);
         }
         complete_and_exit (&ai->thr_exited, 0);
 }
@@ -3064,19 +3193,15 @@ static irqreturn_t airo_interrupt ( int irq, void* dev_id, struct pt_regs *regs)
                          * and reassociations as valid status
                          * Jean II */
                         if(newStatus == ASSOCIATED) {
-                                if (apriv->scan_timestamp) {
-                                        /* Send an empty event to user space.
-                                         * We don't send the received data on
-                                         * the event because it would require
-                                         * us to do complex transcoding, and
-                                         * we want to minimise the work done in
-                                         * the irq handler. Use a request to
-                                         * extract the data - Jean II */
-                                        wrqu.data.length = 0;
-                                        wrqu.data.flags = 0;
-                                        wireless_send_event(dev, SIOCGIWSCAN, &wrqu, NULL);
-                                        apriv->scan_timestamp = 0;
+#if 0
+                                /* FIXME: Grabbing scan results here
+                                 * seems to be too early???  Just wait for
+                                 * timeout instead. */
+                                if (apriv->scan_timeout > 0) {
+                                        set_bit(JOB_SCAN_RESULTS, &apriv->flags);
+                                        wake_up_interruptible(&apriv->thr_wait);
                                 }
+#endif
                                 if (down_trylock(&apriv->sem) != 0) {
                                         set_bit(JOB_EVENT, &apriv->flags);
                                         wake_up_interruptible(&apriv->thr_wait);
@@ -6992,6 +7117,7 @@ static int airo_set_scan(struct net_device *dev,
         struct airo_info *ai = dev->priv;
         Cmd cmd;
         Resp rsp;
+        int wake = 0;
 
         /* Note : you may have realised that, as this is a SET operation,
          * this is privileged and therefore a normal user can't
@@ -7001,17 +7127,25 @@ static int airo_set_scan(struct net_device *dev,
          * Jean II */
         if (ai->flags & FLAG_RADIO_MASK) return -ENETDOWN;
 
+        if (down_interruptible(&ai->sem))
+                return -ERESTARTSYS;
+
+        /* If there's already a scan in progress, don't
+         * trigger another one. */
+        if (ai->scan_timeout > 0)
+                goto out;
+
         /* Initiate a scan command */
         memset(&cmd, 0, sizeof(cmd));
         cmd.cmd=CMD_LISTBSS;
-        if (down_interruptible(&ai->sem))
-                return -ERESTARTSYS;
         issuecommand(ai, &cmd, &rsp);
-        ai->scan_timestamp = jiffies;
-        up(&ai->sem);
-
-        /* At this point, just return to the user. */
+        ai->scan_timeout = RUN_AT(3*HZ);
+        wake = 1;
 
+out:
+        up(&ai->sem);
+        if (wake)
+                wake_up_interruptible(&ai->thr_wait);
         return 0;
 }
 
@@ -7131,59 +7265,38 @@ static int airo_get_scan(struct net_device *dev,
                          char *extra)
 {
         struct airo_info *ai = dev->priv;
-        BSSListRid BSSList;
-        int rc;
+        BSSListElement *net;
+        int err = 0;
         char *current_ev = extra;
 
-        /* When we are associated again, the scan has surely finished.
-         * Just in case, let's make sure enough time has elapsed since
-         * we started the scan. - Javier */
-        if(ai->scan_timestamp && time_before(jiffies,ai->scan_timestamp+3*HZ)) {
-                /* Important note : we don't want to block the caller
-                 * until results are ready for various reasons.
-                 * First, managing wait queues is complex and racy
-                 * (there may be multiple simultaneous callers).
-                 * Second, we grab some rtnetlink lock before comming
-                 * here (in dev_ioctl()).
-                 * Third, the caller can wait on the Wireless Event
-                 * - Jean II */
+        /* If a scan is in-progress, return -EAGAIN */
+        if (ai->scan_timeout > 0)
                 return -EAGAIN;
-        }
-        ai->scan_timestamp = 0;
-
-        /* There's only a race with proc_BSSList_open(), but its
-         * consequences are begnign. So I don't bother fixing it - Javier */
 
-        /* Try to read the first entry of the scan result */
-        rc = PC4500_readrid(ai, RID_BSSLISTFIRST, &BSSList, sizeof(BSSList), 1);
-        if((rc) || (BSSList.index == 0xffff)) {
-                /* Client error, no scan results...
-                 * The caller need to restart the scan. */
-                return -ENODATA;
-        }
+        if (down_interruptible(&ai->sem))
+                return -EAGAIN;
 
-        /* Read and parse all entries */
-        while((!rc) && (BSSList.index != 0xffff)) {
+        list_for_each_entry (net, &ai->network_list, list) {
                 /* Translate to WE format this entry */
                 current_ev = airo_translate_scan(dev, current_ev,
                                                  extra + dwrq->length,
-                                                 &BSSList);
+                                                 &net->bss);
 
                 /* Check if there is space for one more entry */
                 if((extra + dwrq->length - current_ev) <= IW_EV_ADDR_LEN) {
                         /* Ask user space to try again with a bigger buffer */
-                        return -E2BIG;
+                        err = -E2BIG;
+                        goto out;
                 }
-
-                /* Read next entry */
-                rc = PC4500_readrid(ai, RID_BSSLISTNEXT,
-                                    &BSSList, sizeof(BSSList), 1);
         }
+
         /* Length of data */
         dwrq->length = (current_ev - extra);
         dwrq->flags = 0;        /* todo */
 
-        return 0;
+out:
+        up(&ai->sem);
+        return err;
 }
 
 /*------------------------------------------------------------------*/