[PATCH v3 4/7] ACPI: RISC-V: Fix riscv_acpi_add_prt_dep() loop handling

[Lorenzo Pieralisi <lpieralisi@kernel.org>]

The loop in riscv_acpi_add_prt_dep() includes error conditions that are
handled in a dubious - if not outright wrong - way, by continuining the
loop (which skips and misses the entry pointer update to point to the next
entry).

Rewrite the loop as a for loop (that handles the continuation correctly)
and wrap the condition and update statements using helper functions to make
it cleaner.

Fixes: 1b173cc4bfcd ("ACPI: RISC-V: Implement function to add implicit dependencies")
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Tested-by: Sunil V L <sunilvl@oss.qualcomm.com>
Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Sunil V L <sunilvl@ventanamicro.com>
---
 drivers/acpi/riscv/irq.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/riscv/irq.c b/drivers/acpi/riscv/irq.c
index 75170151c614..0cdec5dd575e 100644
--- a/drivers/acpi/riscv/irq.c
+++ b/drivers/acpi/riscv/irq.c
@@ -319,6 +319,20 @@ static int riscv_acpi_irq_get_dep(acpi_handle handle, unsigned int index, acpi_h
 	return ctx.rc;
 }
 
+static bool acpi_prt_entry_valid(void *prt_entry)
+{
+	struct acpi_pci_routing_table *entry = prt_entry;
+
+	return entry && entry->length > 0;
+}
+
+static void *acpi_prt_next_entry(void *prt_entry)
+{
+	struct acpi_pci_routing_table *entry = prt_entry;
+
+	return prt_entry + entry->length;
+}
+
 static u32 riscv_acpi_add_prt_dep(acpi_handle handle)
 {
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
@@ -337,7 +351,7 @@ static u32 riscv_acpi_add_prt_dep(acpi_handle handle)
 	}
 
 	entry = buffer.pointer;
-	while (entry && (entry->length > 0)) {
+	for (; acpi_prt_entry_valid(entry); entry = acpi_prt_next_entry(entry)) {
 		if (entry->source[0]) {
 			status = acpi_get_handle(handle, entry->source, &link_handle);
 			if (ACPI_FAILURE(status))
@@ -365,9 +379,6 @@ static u32 riscv_acpi_add_prt_dep(acpi_handle handle)
 			dep_devices.handles[0] = gsi_handle;
 			count += acpi_scan_add_dep(handle, &dep_devices);
 		}
-
-		entry = (struct acpi_pci_routing_table *)
-			((unsigned long)entry + entry->length);
 	}
 
 	kfree(buffer.pointer);

-- 
2.34.1