[TG3]: Convert to non-LLTX

Herbert Xu pointed out that it is unsafe to call netif_tx_disable()
from LLTX drivers because it uses dev->xmit_lock to synchronize
whereas LLTX drivers use private locks.

Convert tg3 to non-LLTX to fix this issue. tg3 is a lockless driver
where hard_start_xmit and tx completion handling can run concurrently
under normal conditions. A tx_lock is only needed to prevent
netif_stop_queue and netif_wake_queue race condtions when the queue
is full.

So whether we use LLTX or non-LLTX, it makes practically no
difference.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 3 deletions

diff --git a/drivers/net/tg3.h b/drivers/net/tg3.h
index 35669e18065..8209da5dd15 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2074,12 +2074,22 @@ struct tg3 {
 
         /* SMP locking strategy:
          *
-         * lock: Held during all operations except TX packet
-         *       processing.
+         * lock: Held during reset, PHY access, timer, and when
+         *       updating tg3_flags and tg3_flags2.
          *
-         * tx_lock: Held during tg3_start_xmit and tg3_tx
+         * tx_lock: Held during tg3_start_xmit and tg3_tx only
+         *          when calling netif_[start|stop]_queue.
+         *          tg3_start_xmit is protected by netif_tx_lock.
          *
          * Both of these locks are to be held with BH safety.
+         *
+         * Because the IRQ handler, tg3_poll, and tg3_start_xmit
+         * are running lockless, it is necessary to completely
+         * quiesce the chip with tg3_netif_stop and tg3_full_lock
+         * before reconfiguring the device.
+         *
+         * indirect_lock: Held when accessing registers indirectly
+         *                with IRQ disabling.
          */
         spinlock_t                      lock;
         spinlock_t                      indirect_lock;