PCI: hv: Use struct_size() helper

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct hv_dr_state {
	...
        struct hv_pcidev_description func[];
};

struct pci_bus_relations {
	...
        struct pci_function_description func[];
} __packed;

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following forms:

offsetof(struct hv_dr_state, func) +
	(sizeof(struct hv_pcidev_description) *
	(relations->device_count))

offsetof(struct pci_bus_relations, func) +
	(sizeof(struct pci_function_description) *
	(bus_rel->device_count))

with:

struct_size(dr, func, relations->device_count)

and

struct_size(bus_rel, func, bus_rel->device_count)

respectively.

Link: https://lore.kernel.org/r/20200525164319.GA13596@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 92092a4..c95e520 100644 (file)
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -2201,10 +2201,8 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
        struct hv_dr_state *dr;
        int i;
 
-       dr = kzalloc(offsetof(struct hv_dr_state, func) +
-                    (sizeof(struct hv_pcidev_description) *
-                     (relations->device_count)), GFP_NOWAIT);
-
+       dr = kzalloc(struct_size(dr, func, relations->device_count),
+                    GFP_NOWAIT);
        if (!dr)
                return;
 
@@ -2238,10 +2236,8 @@ static void hv_pci_devices_present2(struct hv_pcibus_device *hbus,
        struct hv_dr_state *dr;
        int i;
 
-       dr = kzalloc(offsetof(struct hv_dr_state, func) +
-                    (sizeof(struct hv_pcidev_description) *
-                     (relations->device_count)), GFP_NOWAIT);
-
+       dr = kzalloc(struct_size(dr, func, relations->device_count),
+                    GFP_NOWAIT);
        if (!dr)
                return;
 
@@ -2435,9 +2431,8 @@ static void hv_pci_onchannelcallback(void *context)
 
                                bus_rel = (struct pci_bus_relations *)buffer;
                                if (bytes_recvd <
-                                   offsetof(struct pci_bus_relations, func) +
-                                   (sizeof(struct pci_function_description) *
-                                    (bus_rel->device_count))) {
+                                       struct_size(bus_rel, func,
+                                                   bus_rel->device_count)) {
                                        dev_err(&hbus->hdev->device,
                                                "bus relations too small\n");
                                        break;
@@ -2450,9 +2445,8 @@ static void hv_pci_onchannelcallback(void *context)
 
                                bus_rel2 = (struct pci_bus_relations2 *)buffer;
                                if (bytes_recvd <
-                                   offsetof(struct pci_bus_relations2, func) +
-                                   (sizeof(struct pci_function_description2) *
-                                    (bus_rel2->device_count))) {
+                                       struct_size(bus_rel2, func,
+                                                   bus_rel2->device_count)) {
                                        dev_err(&hbus->hdev->device,
                                                "bus relations v2 too small\n");
                                        break;