lib: logic_pio: Avoid possible overlap for unregistering regions

commit 0a27142bd1ee259e24a0be2b0133e5ca5df8da91 upstream.

The code was originally written to not support unregistering logical PIO
regions.

To accommodate supporting unregistering logical PIO regions, subtly modify
LOGIC_PIO_CPU_MMIO region registration code, such that the "end" of the
registered regions is the "end" of the last region, and not the sum of
the sizes of all the registered regions.

Cc: stable@vger.kernel.org
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Signed-off-by: NWei Xu <xuwei5@hisilicon.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

lib/logic_pio.c

@@ -35,7 +35,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 	struct logic_pio_hwaddr *range;
 	resource_size_t start;
 	resource_size_t end;
-	resource_size_t mmio_sz = 0;
+	resource_size_t mmio_end = 0;
 	resource_size_t iio_sz = MMIO_UPPER_LIMIT;
 	int ret = 0;
 
@@ -56,7 +56,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 			/* for MMIO ranges we need to check for overlap */
 			if (start >= range->hw_start + range->size ||
 			    end < range->hw_start) {
-				mmio_sz += range->size;
+				mmio_end = range->io_start + range->size;
 			} else {
 				ret = -EFAULT;
 				goto end_register;
@@ -69,16 +69,16 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range)
 
 	/* range not registered yet, check for available space */
 	if (new_range->flags == LOGIC_PIO_CPU_MMIO) {
-		if (mmio_sz + new_range->size - 1 > MMIO_UPPER_LIMIT) {
+		if (mmio_end + new_range->size - 1 > MMIO_UPPER_LIMIT) {
 			/* if it's too big check if 64K space can be reserved */
-			if (mmio_sz + SZ_64K - 1 > MMIO_UPPER_LIMIT) {
+			if (mmio_end + SZ_64K - 1 > MMIO_UPPER_LIMIT) {
 				ret = -E2BIG;
 				goto end_register;
 			}
 			new_range->size = SZ_64K;
 			pr_warn("Requested IO range too big, new size set to 64K\n");
 		}
-		new_range->io_start = mmio_sz;
+		new_range->io_start = mmio_end;
 	} else if (new_range->flags == LOGIC_PIO_INDIRECT) {
 		if (iio_sz + new_range->size - 1 > IO_SPACE_LIMIT) {
 			ret = -E2BIG;