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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-08 23:07:07 +0200 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2020-05-13 16:55:16 +0200 |
| commit | c18b5bdebd67112314fe73762d269d381ce3073c (patch) | |
| tree | 4aa5b80b971f6638f6dd7e098e8ac8640a113a48 /drivers/dma/qcom | |
| parent | dmaengine: ti: k3-udma: Use PTR_ERR_OR_ZERO() to simplify code (diff) | |
| download | linux-c18b5bdebd67112314fe73762d269d381ce3073c.tar.xz linux-c18b5bdebd67112314fe73762d269d381ce3073c.zip | |
dmaengine: qcom: bam_dma: 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")
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200508210707.GA24136@embeddedor
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma/qcom')
| -rw-r--r-- | drivers/dma/qcom/bam_dma.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c index ef73f65224b1..5a08dd0d3388 100644 --- a/drivers/dma/qcom/bam_dma.c +++ b/drivers/dma/qcom/bam_dma.c @@ -74,7 +74,7 @@ struct bam_async_desc { struct list_head desc_node; enum dma_transfer_direction dir; size_t length; - struct bam_desc_hw desc[0]; + struct bam_desc_hw desc[]; }; enum bam_reg { |