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| author |   Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 14:00:38 -0500 |
|---|---|---|
| committer |   Vinod Koul <vkoul@kernel.org> | 2020-05-13 20:25:16 +0530 |
| commit | e05a0b78f39f39488c3ea8866aee2b953e206a02 (patch) | |
| tree | 8559e8bb52b1d54fe340c2dc2f7823ed39eaed15 /drivers/dma | |
| parent | dmaengine: qcom: bam_dma: Replace zero-length array with flexible-array (diff) | |
| download | linux-dev-e05a0b78f39f39488c3ea8866aee2b953e206a02.tar.xz linux-dev-e05a0b78f39f39488c3ea8866aee2b953e206a02.zip | |
dmaengine: at_hdmac: 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>
Acked-by: Ludovic Desroches<ludovic.desroches@microchip.com>
Link: https://lore.kernel.org/r/20200507190038.GA15272@embeddedor
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/at_hdmac_regs.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h index 397692e937b3..80fc2fe8c77e 100644 --- a/drivers/dma/at_hdmac_regs.h +++ b/drivers/dma/at_hdmac_regs.h @@ -331,7 +331,7 @@ struct at_dma { struct dma_pool *dma_desc_pool; struct dma_pool *memset_pool; /* AT THE END channels table */ - struct at_dma_chan chan[0]; + struct at_dma_chan chan[]; }; #define dma_readl(atdma, name) \ |