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PCI: hv: Replace zero-length array with flexible-array member

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The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
This commit is contained in:
Gustavo A. R. Silva
2020-02-12 18:50:48 -06:00
committed by Lorenzo Pieralisi
parent 999dd956d8
commit 067fb6c97e
1 changed files with 4 additions and 4 deletions
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8
drivers/pci/controller/pci-hyperv.c
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@@ -283,7 +283,7 @@ struct pci_packet {
int resp_packet_size);
void *compl_ctxt;
struct pci_message message[0];
struct pci_message message[];
};
/*
@@ -319,13 +319,13 @@ struct pci_bus_d0_entry {
struct pci_bus_relations {
struct pci_incoming_message incoming;
u32 device_count;
struct pci_function_description func[0];
struct pci_function_description func[];
} __packed;
struct pci_bus_relations2 {
struct pci_incoming_message incoming;
u32 device_count;
struct pci_function_description2 func[0];
struct pci_function_description2 func[];
} __packed;
struct pci_q_res_req_response {
@@ -551,7 +551,7 @@ struct hv_pcidev_description {
struct hv_dr_state {
struct list_head list_entry;
u32 device_count;
struct hv_pcidev_description func[0];
struct hv_pcidev_description func[];
};
enum hv_pcichild_state {