[TG3]: Eliminate all hw IRQ handler spinlocks.
Move all driver spinlocks to be taken at sw IRQ
context only.
This fixes the skb_copy() we were doing with hw
IRQs disabled (which is illegal and triggers a
BUG() with HIGHMEM enabled). It also simplifies
the locking all over the driver tremendously.
We accomplish this feat by creating a special
sequence to synchronize with the hw IRQ handler
using a binary state and synchronize_irq().
This idea is from Herbert Xu.
Thanks to Michael Chan for helping to track down
all of the race conditions in initial versions
of this code.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tg3.h b/drivers/net/tg3.h
index 993f84c..99c5f96 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2006,17 +2006,31 @@
struct tg3 {
/* begin "general, frequently-used members" cacheline section */
+ /* If the IRQ handler (which runs lockless) needs to be
+ * quiesced, the following bitmask state is used. The
+ * SYNC flag is set by non-IRQ context code to initiate
+ * the quiescence.
+ *
+ * When the IRQ handler notices that SYNC is set, it
+ * disables interrupts and returns.
+ *
+ * When all outstanding IRQ handlers have returned after
+ * the SYNC flag has been set, the setter can be assured
+ * that interrupts will no longer get run.
+ *
+ * In this way all SMP driver locks are never acquired
+ * in hw IRQ context, only sw IRQ context or lower.
+ */
+ unsigned int irq_sync;
+
/* SMP locking strategy:
*
* lock: Held during all operations except TX packet
* processing.
*
- * tx_lock: Held during tg3_start_xmit{,_4gbug} and tg3_tx
+ * tx_lock: Held during tg3_start_xmit and tg3_tx
*
- * If you want to shut up all asynchronous processing you must
- * acquire both locks, 'lock' taken before 'tx_lock'. IRQs must
- * be disabled to take 'lock' but only softirq disabling is
- * necessary for acquisition of 'tx_lock'.
+ * Both of these locks are to be held with BH safety.
*/
spinlock_t lock;
spinlock_t indirect_lock;