Messages in this thread | | | Subject | Re: [PATCH] platform/x86: i2c-multi-instantiate: Replace zero-length array with flexible-array member | From | Hans de Goede <> | Date | Thu, 27 Feb 2020 20:01:25 +0100 |
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Hi,
On 2/27/20 8:03 PM, Gustavo A. R. Silva wrote: > Hi all, > > Friendly ping: who can take this?
FWIW, the patch looks good to me:
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Regards,
Hans
> On 2/12/20 18:55, Gustavo A. R. Silva wrote: >> 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/platform/x86/i2c-multi-instantiate.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/platform/x86/i2c-multi-instantiate.c b/drivers/platform/x86/i2c-multi-instantiate.c >> index ffb8d5d1eb5f..6acc8457866e 100644 >> --- a/drivers/platform/x86/i2c-multi-instantiate.c >> +++ b/drivers/platform/x86/i2c-multi-instantiate.c >> @@ -28,7 +28,7 @@ struct i2c_inst_data { >> >> struct i2c_multi_inst_data { >> int num_clients; >> - struct i2c_client *clients[0]; >> + struct i2c_client *clients[]; >> }; >> >> static int i2c_multi_inst_count(struct acpi_resource *ares, void *data) >> >
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