cxgb3 - Safeguard TCAM size usage

Ensure that the TCAM active region size is at least 16.
Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/cxgb3/common.h

@@ -358,6 +358,9 @@ enum {
 	MC5_MODE_72_BIT = 2
 };
 
+/* MC5 min active region size */
+enum { MC5_MIN_TIDS = 16 };
+
 struct vpd_params {
 	unsigned int cclk;
 	unsigned int mclk;

drivers/net/cxgb3/cxgb3_main.c

@@ -485,12 +485,14 @@ static ssize_t show_##name(struct device *d, struct device_attribute *attr, \
 static ssize_t set_nfilters(struct net_device *dev, unsigned int val)
 {
 	struct adapter *adap = dev->priv;
+	int min_tids = is_offload(adap) ? MC5_MIN_TIDS : 0;
 
 	if (adap->flags & FULL_INIT_DONE)
 		return -EBUSY;
 	if (val && adap->params.rev == 0)
 		return -EINVAL;
-	if (val > t3_mc5_size(&adap->mc5) - adap->params.mc5.nservers)
+	if (val > t3_mc5_size(&adap->mc5) - adap->params.mc5.nservers -
+	    min_tids)
 		return -EINVAL;
 	adap->params.mc5.nfilters = val;
 	return 0;
@@ -508,7 +510,8 @@ static ssize_t set_nservers(struct net_device *dev, unsigned int val)
 
 	if (adap->flags & FULL_INIT_DONE)
 		return -EBUSY;
-	if (val > t3_mc5_size(&adap->mc5) - adap->params.mc5.nfilters)
+	if (val > t3_mc5_size(&adap->mc5) - adap->params.mc5.nfilters -
+	    MC5_MIN_TIDS)
 		return -EINVAL;
 	adap->params.mc5.nservers = val;
 	return 0;

drivers/net/cxgb3/cxgb3_offload.c

@@ -553,7 +553,9 @@ int cxgb3_alloc_atid(struct t3cdev *tdev, struct cxgb3_client *client,
 	struct tid_info *t = &(T3C_DATA(tdev))->tid_maps;
 
 	spin_lock_bh(&t->atid_lock);
-	if (t->afree) {
+	if (t->afree &&
+	    t->atids_in_use + atomic_read(&t->tids_in_use) + MC5_MIN_TIDS <=
+	    t->ntids) {
 		union active_open_entry *p = t->afree;
 
 		atid = (p - t->atid_tab) + t->atid_base;