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| author |   Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 14:05:44 -0500 |
|---|---|---|
| committer |   Bjorn Helgaas <bhelgaas@google.com> | 2020-05-12 08:14:59 -0500 |
| commit | 914a1951d88968371c7d43400c9d936382cd7d69 (patch) | |
| tree | d29da9e122598cfb78cbc2182a1450ca4e43fa75 /include/linux/pci.h | |
| parent | PCI: Check for platform_get_irq() failure consistently (diff) | |
| download | wireguard-linux-914a1951d88968371c7d43400c9d936382cd7d69.tar.xz wireguard-linux-914a1951d88968371c7d43400c9d936382cd7d69.zip | |
PCI: Replace zero-length array with flexible-array
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 as 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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type [1]. There are some instances of code in which
the sizeof() operator is being incorrectly/erroneously applied to
zero-length arrays, and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also help
to get completely rid of those sorts of issues.
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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Link: https://lore.kernel.org/r/20200507190544.GA15633@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'include/linux/pci.h')
| -rw-r--r-- | include/linux/pci.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/pci.h b/include/linux/pci.h index 83ce1cdf5676..0453ee458ab1 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -279,7 +279,7 @@ struct pci_cap_saved_data { u16 cap_nr; bool cap_extended; unsigned int size; - u32 data[0]; + u32 data[]; }; struct pci_cap_saved_state { @@ -532,7 +532,7 @@ struct pci_host_bridge { resource_size_t start, resource_size_t size, resource_size_t align); - unsigned long private[0] ____cacheline_aligned; + unsigned long private[] ____cacheline_aligned; }; #define to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev) |