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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 14:00:46 -0500
committerVinod Koul <vkoul@kernel.org>2020-05-13 20:25:41 +0530
commitd9fd428a304f2e33caf609011cdc9f17a8d3fb9e (patch)
tree9048b022b66a78c4c0f08e6785300a8f82f4bf08 /drivers/dma
parente05a0b78f39f39488c3ea8866aee2b953e206a02 (diff)
dmaengine: at_xdmac: 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/20200507190046.GA15298@embeddedor Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/at_xdmac.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index bb0eaf38b594..fd92f048c491 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -212,7 +212,7 @@ struct at_xdmac {
struct clk *clk;
u32 save_gim;
struct dma_pool *at_xdmac_desc_pool;
- struct at_xdmac_chan chan[0];
+ struct at_xdmac_chan chan[];
};