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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]
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")
Signed-off-by: Gustavo A. R. Silva <[email protected]>
Link: https://lore.kernel.org/r/20200507185318.GA14393@embeddedor
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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Before moving greybus core out of staging and moving header files to
include/linux some greybus header files were missing the necessary
includes. This would trigger compilation faillures with some example
errors logged bellow for with CONFIG_KERNEL_HEADER_TEST=y.
So, add the necessary headers to compile clean before relocating the
header files.
./include/linux/greybus/hd.h:23:50: error: unknown type name 'u16'
int (*cport_disable)(struct gb_host_device *hd, u16 cport_id); ^~~
./include/linux/greybus/greybus_protocols.h:1314:2: error: unknown type name '__u8'
__u8 data[0];
^~~~
./include/linux/greybus/hd.h:24:52: error: unknown type name 'u16'
int (*cport_connected)(struct gb_host_device *hd, u16 cport_id); ^~~
./include/linux/greybus/hd.h:25:48: error: unknown type name 'u16'
int (*cport_flush)(struct gb_host_device *hd, u16 cport_id); ^~~
./include/linux/greybus/hd.h:26:51: error: unknown type name 'u16'
int (*cport_shutdown)(struct gb_host_device *hd, u16 cport_id, ^~~
./include/linux/greybus/hd.h:27:5: error: unknown type name 'u8'
u8 phase, unsigned int timeout);
^~
./include/linux/greybus/hd.h:28:50: error: unknown type name 'u16'
int (*cport_quiesce)(struct gb_host_device *hd, u16 cport_id, ^~~
./include/linux/greybus/hd.h:29:5: error: unknown type name 'size_t'
size_t peer_space, unsigned int timeout);
^~~~~~
./include/linux/greybus/hd.h:29:5: note: 'size_t' is defined in header '<stddef.h>'; did you forget to '#include <stddef.h>'?
./include/linux/greybus/hd.h:1:1:
+#include <stddef.h>
/* SPDX-License-Identifier: GPL-2.0 */
./include/linux/greybus/hd.h:29:5:
size_t peer_space, unsigned int timeout);
^~~~~~
./include/linux/greybus/hd.h:30:48: error: unknown type name 'u16'
int (*cport_clear)(struct gb_host_device *hd, u16 cport_id); ^~~
./include/linux/greybus/hd.h:32:49: error: unknown type name 'u16'
int (*message_send)(struct gb_host_device *hd, u16 dest_cport_id, ^~~
./include/linux/greybus/hd.h:33:32: error: unknown type name 'gfp_t'
struct gb_message *message, gfp_t gfp_mask); ^~~~~
./include/linux/greybus/hd.h:35:55: error: unknown type name 'u16'
int (*latency_tag_enable)(struct gb_host_device *hd, u16 cport_id);
Reported-by: kbuild test robot <[email protected]>
Reported-by: Gao Xiang <[email protected]>
Signed-off-by: Rui Miguel Silva <[email protected]>
Signed-off-by: Rui Miguel Silva <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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