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>
diff --git a/drivers/net/cxgb3/common.h b/drivers/net/cxgb3/common.h
index 85e5543..38a0565 100644
--- a/drivers/net/cxgb3/common.h
+++ b/drivers/net/cxgb3/common.h
@@ -358,6 +358,9 @@
 	MC5_MODE_72_BIT = 2
 };
 
+/* MC5 min active region size */
+enum { MC5_MIN_TIDS = 16 };
+
 struct vpd_params {
 	unsigned int cclk;
 	unsigned int mclk;
diff --git a/drivers/net/cxgb3/cxgb3_main.c b/drivers/net/cxgb3/cxgb3_main.c
index d553836..b82544e 100644
--- a/drivers/net/cxgb3/cxgb3_main.c
+++ b/drivers/net/cxgb3/cxgb3_main.c
@@ -485,12 +485,14 @@
 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 @@
 
 	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;
diff --git a/drivers/net/cxgb3/cxgb3_offload.c b/drivers/net/cxgb3/cxgb3_offload.c
index f6ed033..eed7a48 100644
--- a/drivers/net/cxgb3/cxgb3_offload.c
+++ b/drivers/net/cxgb3/cxgb3_offload.c
@@ -553,7 +553,9 @@
 	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;