alistair23-linux/drivers/dma/qcom
Gustavo A. R. Silva c18b5bdebd 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 7649773293 ("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>
2020-05-13 20:25:16 +05:30
..
bam_dma.c dmaengine: qcom: bam_dma: Replace zero-length array with flexible-array 2020-05-13 20:25:16 +05:30
hidma.c dmaengine: qcom_hidma: use true,false for bool variable 2020-05-13 17:06:32 +05:30
hidma.h dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
hidma_dbg.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
hidma_ll.c dmaengine: qcom_hidma: Remove call to memset after dmam_alloc_coherent 2019-08-08 17:51:56 +05:30
hidma_mgmt.c dmaengine: qcom: hidma_mgmt: Add of_node_put() before goto 2019-08-08 17:56:50 +05:30
hidma_mgmt.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 284 2019-06-05 17:36:37 +02:00
hidma_mgmt_sys.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 284 2019-06-05 17:36:37 +02:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00