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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-20 07:20:17 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-02-23 19:24:51 +0100 |
| commit | 6bc3f3979edce0b11deb685a4c817abb7d74b227 (patch) | |
| tree | 3ce2cf2b7886400097251d33c05435653bcafe9b /drivers/usb/host/xhci.h | |
| parent | 2f41c8a25feb822203f92e17f3720397805d0cfd (diff) | |
| download | linux-6bc3f3979edce0b11deb685a4c817abb7d74b227.tar.gz | |
USB: Replace zero-length array with flexible-array member
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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200220132017.GA29262@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/host/xhci.h')
| -rw-r--r-- | drivers/usb/host/xhci.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 13d8838cd552..5f47b18609ee 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1642,7 +1642,7 @@ struct xhci_scratchpad { struct urb_priv { int num_tds; int num_tds_done; - struct xhci_td td[0]; + struct xhci_td td[]; }; /* @@ -1893,7 +1893,7 @@ struct xhci_hcd { void *dbc; /* platform-specific data -- must come last */ - unsigned long priv[0] __aligned(sizeof(s64)); + unsigned long priv[] __aligned(sizeof(s64)); }; /* Platform specific overrides to generic XHCI hc_driver ops */ |