[PATCH 0/5] usb: isp1760: clang analyzer fixes

[PATCH 0/5] usb: isp1760: clang analyzer fixes

[Rui Miguel Silva]

This are fixes for new and pre existing warnings noted by clang
analyzer in this driver which complains about some unused read values,
shift left using negative uninitialized slot numbers and zero
maxpacketsize.

Cheers,
  Rui

Rui Miguel Silva (5):
  usb: isp1760: ignore return value for bus change pattern
  usb: isp1760: check maxpacketsize before using it
  usb: isp1760: do not reset retval
  usb: isp1760: do not shift in uninitialized slot
  usb: isp1760: clean never read udc_enabled warning

 drivers/usb/isp1760/isp1760-core.c |  4 ++--
 drivers/usb/isp1760/isp1760-hcd.c  | 31 ++++++++++++++++++------------
 2 files changed, 21 insertions(+), 14 deletions(-)

-- 
2.33.0

[PATCH 1/5] usb: isp1760: ignore return value for bus change pattern

[Rui Miguel Silva]

We do not care about the return value of that read between the
scratch register write and read, we really just want to make sure that
the pattern in the bus get changed to make sure we are testing
correctly the scratch pattern.

Clang-analyzer complains about the never read scratch variable:
>> drivers/usb/isp1760/isp1760-hcd.c:735:2: warning: Value stored to 'scratch' is never read [clang-analyzer-deadcode.DeadStores]
    scratch = isp1760_hcd_read(hcd, HC_CHIP_ID_HIGH);

Just ignore the return value of that CHIP_ID_HIGH read, add more
information to the comment above why we are doing this. And as at it,
just do a small format change in the error message bellow.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
---
 drivers/usb/isp1760/isp1760-hcd.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/isp1760/isp1760-hcd.c b/drivers/usb/isp1760/isp1760-hcd.c
index 825be736be33..2a21fe5aa7a8 100644
--- a/drivers/usb/isp1760/isp1760-hcd.c
+++ b/drivers/usb/isp1760/isp1760-hcd.c
@@ -731,11 +731,15 @@ static int isp1760_hc_setup(struct usb_hcd *hcd)
 
 	isp1760_hcd_write(hcd, HC_SCRATCH, pattern);
 
-	/* Change bus pattern */
-	scratch = isp1760_hcd_read(hcd, HC_CHIP_ID_HIGH);
+	/*
+	 * we do not care about the read value here we just want to
+	 * change bus pattern.
+	 */
+	isp1760_hcd_read(hcd, HC_CHIP_ID_HIGH);
 	scratch = isp1760_hcd_read(hcd, HC_SCRATCH);
 	if (scratch != pattern) {
-		dev_err(hcd->self.controller, "Scratch test failed. 0x%08x\n", scratch);
+		dev_err(hcd->self.controller, "Scratch test failed. 0x%08x\n",
+			scratch);
 		return -ENODEV;
 	}
 
-- 
2.33.0

[PATCH 2/5] usb: isp1760: check maxpacketsize before using it

[Rui Miguel Silva]

When checking if we need one more packet on a bulk pipe we may, even
though not probable at all, get there with a zero maxpacketsize.
In that case for sure no packet, no even a one more, will be
allocated.

This will clean the clang-analyzer warning:
drivers/usb/isp1760/isp1760-hcd.c:1856:38: warning: Division by zero [clang-analyzer-core.DivideZero]
                                && !(urb->transfer_buffer_length %

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
---
 drivers/usb/isp1760/isp1760-hcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/isp1760/isp1760-hcd.c b/drivers/usb/isp1760/isp1760-hcd.c
index 2a21fe5aa7a8..5c947a1eae49 100644
--- a/drivers/usb/isp1760/isp1760-hcd.c
+++ b/drivers/usb/isp1760/isp1760-hcd.c
@@ -1854,7 +1854,7 @@ static void packetize_urb(struct usb_hcd *hcd,
 				packet_type = OUT_PID;
 			else
 				packet_type = IN_PID;
-		} else if (usb_pipebulk(urb->pipe)
+		} else if (usb_pipebulk(urb->pipe) && maxpacketsize
 				&& (urb->transfer_flags & URB_ZERO_PACKET)
 				&& !(urb->transfer_buffer_length %
 							maxpacketsize)) {
-- 
2.33.0

[PATCH 3/5] usb: isp1760: do not reset retval

[Rui Miguel Silva]

We do not really need to reset retval before get used bellow.
This will avoid the clang-analyzer warning:

drivers/usb/isp1760/isp1760-hcd.c:1919:2: warning: Value stored to 'retval' is never read [clang-analyzer-deadcode.DeadStores]
        retval = 0;

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
---
 drivers/usb/isp1760/isp1760-hcd.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/usb/isp1760/isp1760-hcd.c b/drivers/usb/isp1760/isp1760-hcd.c
index 5c947a1eae49..aed2714ce0cf 100644
--- a/drivers/usb/isp1760/isp1760-hcd.c
+++ b/drivers/usb/isp1760/isp1760-hcd.c
@@ -1919,7 +1919,6 @@ static int isp1760_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
 	if (list_empty(&new_qtds))
 		return -ENOMEM;
 
-	retval = 0;
 	spin_lock_irqsave(&priv->lock, spinflags);
 
 	if (!test_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags)) {
-- 
2.33.0

[PATCH 4/5] usb: isp1760: do not shift in uninitialized slot

[Rui Miguel Silva]

Even though it is not expected, and would trigger a WARN_ON, killing a
transfer in a uninitialized slot this sequence is warned by clang
analyzer, twice:

drivers/usb/isp1760/isp1760-hcd.c:1976:18: warning: The result of the left shift is undefined because the right operand is negative [clang-analyzer-core.UndefinedBinaryOperatorResult]
                skip_map |= (1 << qh->slot);
drivers/usb/isp1760/isp1760-hcd.c:1983:18: warning: The result of the left shift is undefined because the right operand is negative [clang-analyzer-core.UndefinedBinaryOperatorResult]
                skip_map |= (1 << qh->slot);

Only set skip map if slot is active.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
---
 drivers/usb/isp1760/isp1760-hcd.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/isp1760/isp1760-hcd.c b/drivers/usb/isp1760/isp1760-hcd.c
index aed2714ce0cf..bf8ab3fe2e5a 100644
--- a/drivers/usb/isp1760/isp1760-hcd.c
+++ b/drivers/usb/isp1760/isp1760-hcd.c
@@ -1974,16 +1974,20 @@ static void kill_transfer(struct usb_hcd *hcd, struct urb *urb,
 	/* We need to forcefully reclaim the slot since some transfers never
 	   return, e.g. interrupt transfers and NAKed bulk transfers. */
 	if (usb_pipecontrol(urb->pipe) || usb_pipebulk(urb->pipe)) {
-		skip_map = isp1760_hcd_read(hcd, HC_ATL_PTD_SKIPMAP);
-		skip_map |= (1 << qh->slot);
-		isp1760_hcd_write(hcd, HC_ATL_PTD_SKIPMAP, skip_map);
-		ndelay(100);
+		if (qh->slot != -1) {
+			skip_map = isp1760_hcd_read(hcd, HC_ATL_PTD_SKIPMAP);
+			skip_map |= (1 << qh->slot);
+			isp1760_hcd_write(hcd, HC_ATL_PTD_SKIPMAP, skip_map);
+			ndelay(100);
+		}
 		priv->atl_slots[qh->slot].qh = NULL;
 		priv->atl_slots[qh->slot].qtd = NULL;
 	} else {
-		skip_map = isp1760_hcd_read(hcd, HC_INT_PTD_SKIPMAP);
-		skip_map |= (1 << qh->slot);
-		isp1760_hcd_write(hcd, HC_INT_PTD_SKIPMAP, skip_map);
+		if (qh->slot != -1) {
+			skip_map = isp1760_hcd_read(hcd, HC_INT_PTD_SKIPMAP);
+			skip_map |= (1 << qh->slot);
+			isp1760_hcd_write(hcd, HC_INT_PTD_SKIPMAP, skip_map);
+		}
 		priv->int_slots[qh->slot].qh = NULL;
 		priv->int_slots[qh->slot].qtd = NULL;
 	}
-- 
2.33.0

[PATCH 5/5] usb: isp1760: clean never read udc_enabled warning

[Rui Miguel Silva]

When CONFIG_USB_ISP1761_UDC is not enabled the udc_enabled variable is
never used since it is short circuited before in the logic operations.

This would trigger the following warning by clang analyzer:

drivers/usb/isp1760/isp1760-core.c:490:2: warning: Value stored to 'udc_enabled' is never read [clang-analyzer-deadcode.DeadStores]
        udc_enabled = ((devflags & ISP1760_FLAG_ISP1763) ||
        ^
drivers/usb/isp1760/isp1760-core.c:490:2: note: Value stored to 'udc_enabled' is never read

Just swap the other of the operands in the logic operations.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
---
 drivers/usb/isp1760/isp1760-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/isp1760/isp1760-core.c b/drivers/usb/isp1760/isp1760-core.c
index ff07e2890692..cb70f9d63cdd 100644
--- a/drivers/usb/isp1760/isp1760-core.c
+++ b/drivers/usb/isp1760/isp1760-core.c
@@ -491,7 +491,7 @@ int isp1760_register(struct resource *mem, int irq, unsigned long irqflags,
 		       (devflags & ISP1760_FLAG_ISP1761));
 
 	if ((!IS_ENABLED(CONFIG_USB_ISP1760_HCD) || usb_disabled()) &&
-	    (!IS_ENABLED(CONFIG_USB_ISP1761_UDC) || !udc_enabled))
+	    (!udc_enabled || !IS_ENABLED(CONFIG_USB_ISP1761_UDC)))
 		return -ENODEV;
 
 	isp = devm_kzalloc(dev, sizeof(*isp), GFP_KERNEL);
@@ -571,7 +571,7 @@ int isp1760_register(struct resource *mem, int irq, unsigned long irqflags,
 			return ret;
 	}
 
-	if (IS_ENABLED(CONFIG_USB_ISP1761_UDC) && udc_enabled) {
+	if (udc_enabled && IS_ENABLED(CONFIG_USB_ISP1761_UDC)) {
 		ret = isp1760_udc_register(isp, irq, irqflags);
 		if (ret < 0) {
 			isp1760_hcd_unregister(hcd);
-- 
2.33.0