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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 13:53:18 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-05-13 13:59:13 +0200
commit84c1e51d7df85332705ffebc40ef135205492036 (patch)
treef46ff0b0db248f95b67ee1f9e9b77645851b2d90 /drivers/greybus
parentdd92b0133a78457e909da1d5916a05c342a897d6 (diff)
greybus: 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 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 <gustavoars@kernel.org> Link: https://lore.kernel.org/r/20200507185318.GA14393@embeddedor Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/greybus')
-rw-r--r--drivers/greybus/arpc.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/greybus/arpc.h b/drivers/greybus/arpc.h
index c8b83c5cfa79..b9ea81b55b29 100644
--- a/drivers/greybus/arpc.h
+++ b/drivers/greybus/arpc.h
@@ -21,7 +21,7 @@ struct arpc_request_message {
__le16 id; /* RPC unique id */
__le16 size; /* Size in bytes of header + payload */
__u8 type; /* RPC type */
- __u8 data[0]; /* ARPC data */
+ __u8 data[]; /* ARPC data */
} __packed;
struct arpc_response_message {