linux-kernel - [PATCH v1 1/1] IB/hfi1: Don't cast parameter in bit operations

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Date:   Wed, 23 Feb 2022 20:53:53 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...pe.ca>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Mike Marciniszyn <mike.marciniszyn@...nelisnetworks.com>,
        Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v1 1/1] IB/hfi1: Don't cast parameter in bit operations

While in this particular case it would not be a (critical) issue,
the pattern itself is bad and error prone in case somebody blindly
copies to their code.

Don't cast parameter to unsigned long pointer in the bit operations.
Instead copy to a local variable on stack of a proper type and use.

Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/infiniband/hw/hfi1/chip.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
index f1245c94ae26..100274b926d3 100644
--- a/drivers/infiniband/hw/hfi1/chip.c
+++ b/drivers/infiniband/hw/hfi1/chip.c
@@ -8286,34 +8286,33 @@ static void is_interrupt(struct hfi1_devdata *dd, unsigned int source)
 irqreturn_t general_interrupt(int irq, void *data)
 {
 	struct hfi1_devdata *dd = data;
-	u64 regs[CCE_NUM_INT_CSRS];
+	DECLARE_BITMAP(pending, CCE_NUM_INT_CSRS * 64);
+	u64 value;
 	u32 bit;
 	int i;
-	irqreturn_t handled = IRQ_NONE;
 
 	this_cpu_inc(*dd->int_counter);
 
 	/* phase 1: scan and clear all handled interrupts */
 	for (i = 0; i < CCE_NUM_INT_CSRS; i++) {
-		if (dd->gi_mask[i] == 0) {
-			regs[i] = 0;	/* used later */
-			continue;
-		}
-		regs[i] = read_csr(dd, CCE_INT_STATUS + (8 * i)) &
-				dd->gi_mask[i];
+		if (dd->gi_mask[i] == 0)
+			value = 0;	/* used later */
+		else
+			value = read_csr(dd, CCE_INT_STATUS + (8 * i)) & dd->gi_mask[i];
+
+		/* save for further use */
+		bitmap_from_u64(&pending[BITS_TO_LONGS(i * 64)], value);
+
 		/* only clear if anything is set */
-		if (regs[i])
-			write_csr(dd, CCE_INT_CLEAR + (8 * i), regs[i]);
+		if (value)
+			write_csr(dd, CCE_INT_CLEAR + (8 * i), value);
 	}
 
 	/* phase 2: call the appropriate handler */
-	for_each_set_bit(bit, (unsigned long *)&regs[0],
-			 CCE_NUM_INT_CSRS * 64) {
+	for_each_set_bit(bit, pending, CCE_NUM_INT_CSRS * 64)
 		is_interrupt(dd, bit);
-		handled = IRQ_HANDLED;
-	}
 
-	return handled;
+	return IRQ_RETVAL(!bitmap_empty(pending, CCE_NUM_INT_CSRS * 64));
 }
 
 irqreturn_t sdma_interrupt(int irq, void *data)
-- 
2.34.1