| Message ID | 20200213001401.GA28587@embeddedor.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | e26060e1d47a535e0bc41a00708b79bc52dc9fb3 |
| Headers | show |
| Series | iommu/qcom: Replace zero-length array with flexible-array member | expand |
On Wed, Feb 12, 2020 at 06:14:01PM -0600, Gustavo A. R. Silva wrote: > drivers/iommu/qcom_iommu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied, thanks.
diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c index 39759db4f003..f1e175ca5e4a 100644 --- a/drivers/iommu/qcom_iommu.c +++ b/drivers/iommu/qcom_iommu.c @@ -48,7 +48,7 @@ struct qcom_iommu_dev { void __iomem *local_base; u32 sec_id; u8 num_ctxs; - struct qcom_iommu_ctx *ctxs[0]; /* indexed by asid-1 */ + struct qcom_iommu_ctx *ctxs[]; /* indexed by asid-1 */ }; struct qcom_iommu_ctx {
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> --- drivers/iommu/qcom_iommu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)