IB/ipath: Fix sendctrl locking

Code review pointed out that the locking around uses of ipath_sendctrl 
and kr_sendctrl were, in several places, incorrect and/or inconsistent.

Signed-off-by: John Gregor <john.gregor@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

6 files changed, 72 insertions, 29 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
index fc355981bba..6a48442a8d5 100644
--- a/drivers/infiniband/hw/ipath/ipath_driver.c
+++ b/drivers/infiniband/hw/ipath/ipath_driver.c
@@ -803,31 +803,37 @@ void ipath_disarm_piobufs(struct ipath_devdata *dd, unsigned first,
 			  unsigned cnt)
 {
 	unsigned i, last = first + cnt;
-	u64 sendctrl, sendorig;
+	unsigned long flags;
 
 	ipath_cdbg(PKT, "disarm %u PIObufs first=%u\n", cnt, first);
-	sendorig = dd->ipath_sendctrl;
 	for (i = first; i < last; i++) {
-		sendctrl = sendorig  | INFINIPATH_S_DISARM |
-			(i << INFINIPATH_S_DISARMPIOBUF_SHIFT);
+		spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+		/*
+		 * The disarm-related bits are write-only, so it
+		 * is ok to OR them in with our copy of sendctrl
+		 * while we hold the lock.
+		 */
 		ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
-				 sendctrl);
+			dd->ipath_sendctrl | INFINIPATH_S_DISARM |
+			(i << INFINIPATH_S_DISARMPIOBUF_SHIFT));
+		/* can't disarm bufs back-to-back per iba7220 spec */
+		ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+		spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 	}
 
 	/*
-	 * Write it again with current value, in case ipath_sendctrl changed
-	 * while we were looping; no critical bits that would require
-	 * locking.
-	 *
-	 * disable PIOAVAILUPD, then re-enable, reading scratch in
+	 * Disable PIOAVAILUPD, then re-enable, reading scratch in
 	 * between.  This seems to avoid a chip timing race that causes
-	 * pioavail updates to memory to stop.
+	 * pioavail updates to memory to stop.  We xor as we don't
+	 * know the state of the bit when we're called.
 	 */
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
-			 sendorig & ~INFINIPATH_S_PIOBUFAVAILUPD);
-	sendorig = ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+		dd->ipath_sendctrl ^ INFINIPATH_S_PIOBUFAVAILUPD);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
 			 dd->ipath_sendctrl);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 }
 
 /**
@@ -2056,6 +2062,8 @@ void ipath_set_led_override(struct ipath_devdata *dd, unsigned int val)
  */
 void ipath_shutdown_device(struct ipath_devdata *dd)
 {
+	unsigned long flags;
+
 	ipath_dbg("Shutting down the device\n");
 
 	dd->ipath_flags |= IPATH_LINKUNK;
@@ -2076,9 +2084,13 @@ void ipath_shutdown_device(struct ipath_devdata *dd)
 	 * gracefully stop all sends allowing any in progress to trickle out
 	 * first.
 	 */
-	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, 0ULL);
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+	dd->ipath_sendctrl = 0;
+	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, dd->ipath_sendctrl);
 	/* flush it */
 	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
+
 	/*
 	 * enough for anything that's going to trickle out to have actually
 	 * done so.
diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c
index 5de3243a47c..92dae6f5b39 100644
--- a/drivers/infiniband/hw/ipath/ipath_file_ops.c
+++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c
@@ -2149,11 +2149,15 @@ static int ipath_get_slave_info(struct ipath_portdata *pd,
 
 static int ipath_force_pio_avail_update(struct ipath_devdata *dd)
 {
-	u64 reg = dd->ipath_sendctrl;
+	unsigned long flags;
 
-	clear_bit(IPATH_S_PIOBUFAVAILUPD, &reg);
-	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, reg);
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
+		dd->ipath_sendctrl & ~INFINIPATH_S_PIOBUFAVAILUPD);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, dd->ipath_sendctrl);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 
 	return 0;
 }
diff --git a/drivers/infiniband/hw/ipath/ipath_init_chip.c b/drivers/infiniband/hw/ipath/ipath_init_chip.c
index 9e9d6fafcf0..1c65ab907a3 100644
--- a/drivers/infiniband/hw/ipath/ipath_init_chip.c
+++ b/drivers/infiniband/hw/ipath/ipath_init_chip.c
@@ -345,7 +345,7 @@ static int init_chip_first(struct ipath_devdata *dd,
 		       dd->ipath_piobcnt2k, dd->ipath_pio2kbase);
 
 	spin_lock_init(&dd->ipath_tid_lock);
-
+	spin_lock_init(&dd->ipath_sendctrl_lock);
 	spin_lock_init(&dd->ipath_gpio_lock);
 	spin_lock_init(&dd->ipath_eep_st_lock);
 	mutex_init(&dd->ipath_eep_lock);
@@ -372,9 +372,9 @@ static int init_chip_reset(struct ipath_devdata *dd,
 	*pdp = dd->ipath_pd[0];
 	/* ensure chip does no sends or receives while we re-initialize */
 	dd->ipath_control = dd->ipath_sendctrl = dd->ipath_rcvctrl = 0U;
-	ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl, 0);
-	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, 0);
-	ipath_write_kreg(dd, dd->ipath_kregs->kr_control, 0);
+	ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl, dd->ipath_rcvctrl);
+	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, dd->ipath_sendctrl);
+	ipath_write_kreg(dd, dd->ipath_kregs->kr_control, dd->ipath_control);
 
 	rtmp = ipath_read_kreg32(dd, dd->ipath_kregs->kr_portcnt);
 	if (dd->ipath_portcnt != rtmp)
@@ -487,6 +487,7 @@ static void enable_chip(struct ipath_devdata *dd,
 			struct ipath_portdata *pd, int reinit)
 {
 	u32 val;
+	unsigned long flags;
 	int i;
 
 	if (!reinit)
@@ -495,11 +496,13 @@ static void enable_chip(struct ipath_devdata *dd,
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
 			 dd->ipath_rcvctrl);
 
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
 	/* Enable PIO send, and update of PIOavail regs to memory. */
 	dd->ipath_sendctrl = INFINIPATH_S_PIOENABLE |
 		INFINIPATH_S_PIOBUFAVAILUPD;
-	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
-			 dd->ipath_sendctrl);
+	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, dd->ipath_sendctrl);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 
 	/*
 	 * enable port 0 receive, and receive interrupt.  other ports
@@ -696,6 +699,7 @@ int ipath_init_chip(struct ipath_devdata *dd, int reinit)
 	u64 val;
 	struct ipath_portdata *pd = NULL; /* keep gcc4 happy */
 	gfp_t gfp_flags = GFP_USER | __GFP_COMP;
+	unsigned long flags;
 
 	ret = init_housekeeping(dd, &pd, reinit);
 	if (ret)
@@ -827,8 +831,12 @@ int ipath_init_chip(struct ipath_devdata *dd, int reinit)
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_hwerrclear,
 			 ~0ULL&~INFINIPATH_HWE_MEMBISTFAILED);
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_control, 0ULL);
-	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
-			 INFINIPATH_S_PIOENABLE);
+
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+	dd->ipath_sendctrl = INFINIPATH_S_PIOENABLE;
+	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl, dd->ipath_sendctrl);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 
 	/*
 	 * before error clears, since we expect serdes pll errors during
diff --git a/drivers/infiniband/hw/ipath/ipath_intr.c b/drivers/infiniband/hw/ipath/ipath_intr.c
index ad41cccd2e9..eac2e9c5528 100644
--- a/drivers/infiniband/hw/ipath/ipath_intr.c
+++ b/drivers/infiniband/hw/ipath/ipath_intr.c
@@ -795,6 +795,7 @@ void ipath_clear_freeze(struct ipath_devdata *dd)
 {
 	int i, im;
 	__le64 val;
+	unsigned long flags;
 
 	/* disable error interrupts, to avoid confusion */
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_errormask, 0ULL);
@@ -813,11 +814,14 @@ void ipath_clear_freeze(struct ipath_devdata *dd)
 			 dd->ipath_control);
 
 	/* ensure pio avail updates continue */
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
 		 dd->ipath_sendctrl & ~INFINIPATH_S_PIOBUFAVAILUPD);
 	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
-		 dd->ipath_sendctrl);
+			 dd->ipath_sendctrl);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 
 	/*
 	 * We just enabled pioavailupdate, so dma copy is almost certainly
@@ -922,6 +926,7 @@ static noinline void ipath_bad_regread(struct ipath_devdata *dd)
 
 static void handle_layer_pioavail(struct ipath_devdata *dd)
 {
+	unsigned long flags;
 	int ret;
 
 	ret = ipath_ib_piobufavail(dd->verbs_dev);
@@ -930,9 +935,12 @@ static void handle_layer_pioavail(struct ipath_devdata *dd)
 
 	return;
 set:
-	set_bit(IPATH_S_PIOINTBUFAVAIL, &dd->ipath_sendctrl);
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+	dd->ipath_sendctrl |= INFINIPATH_S_PIOINTBUFAVAIL;
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
 			 dd->ipath_sendctrl);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 }
 
 /*
@@ -1168,9 +1176,14 @@ irqreturn_t ipath_intr(int irq, void *data)
 		handle_urcv(dd, istat);
 
 	if (istat & INFINIPATH_I_SPIOBUFAVAIL) {
-		clear_bit(IPATH_S_PIOINTBUFAVAIL, &dd->ipath_sendctrl);
+		unsigned long flags;
+
+		spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+		dd->ipath_sendctrl &= ~INFINIPATH_S_PIOINTBUFAVAIL;
 		ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
 				 dd->ipath_sendctrl);
+		ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+		spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 
 		handle_layer_pioavail(dd);
 	}
diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index 65f7c7f7b5d..81759c2031f 100644
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -376,6 +376,7 @@ struct ipath_devdata {
 	dma_addr_t *ipath_physshadow;
 	/* lock to workaround chip bug 9437 */
 	spinlock_t ipath_tid_lock;
+	spinlock_t ipath_sendctrl_lock;
 
 	/*
 	 * IPATH_STATUS_*,
diff --git a/drivers/infiniband/hw/ipath/ipath_ruc.c b/drivers/infiniband/hw/ipath/ipath_ruc.c
index 54c61a972de..1b4f7e113b2 100644
--- a/drivers/infiniband/hw/ipath/ipath_ruc.c
+++ b/drivers/infiniband/hw/ipath/ipath_ruc.c
@@ -479,9 +479,14 @@ done:
 
 static void want_buffer(struct ipath_devdata *dd)
 {
-	set_bit(IPATH_S_PIOINTBUFAVAIL, &dd->ipath_sendctrl);
+	unsigned long flags;
+
+	spin_lock_irqsave(&dd->ipath_sendctrl_lock, flags);
+	dd->ipath_sendctrl |= INFINIPATH_S_PIOINTBUFAVAIL;
 	ipath_write_kreg(dd, dd->ipath_kregs->kr_sendctrl,
 			 dd->ipath_sendctrl);
+	ipath_read_kreg64(dd, dd->ipath_kregs->kr_scratch);
+	spin_unlock_irqrestore(&dd->ipath_sendctrl_lock, flags);
 }
 
 /**