Re: [PATCH v2 1/1] Bluetooth: make hci_test_bit's addr const

[Marcel Holtmann]

Hi Jiri,

> gcc5 warns about passing a const array to hci_test_bit which takes a
> non-const pointer:
> net/bluetooth/hci_sock.c: In function âhci_sock_sendmsgâ:
> net/bluetooth/hci_sock.c:955:8: warning: passing argument 2 of âhci_test_bitâ discards âconstâ qualifier from pointer target type [-Wdiscarded-array-qualifiers]
>        &hci_sec_filter.ocf_mask[ogf])) &&
>        ^
> net/bluetooth/hci_sock.c:49:19: note: expected âvoid *â but argument is of type âconst __u32 (*)[4] {aka const unsigned int (*)[4]}â
> static inline int hci_test_bit(int nr, void *addr)
>                   ^
> 
> So make 'addr' 'const void *'.
> 
> [v2] make the pointer in the cast const too. 
> 
> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
> Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
> Cc: Gustavo Padovan <gustavo@xxxxxxxxxxx>
> Cc: Johan Hedberg <johan.hedberg@xxxxxxxxx>
> ---
> net/bluetooth/hci_sock.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
> index 1d65c5be7c82..d1a7d67619d8 100644
> --- a/net/bluetooth/hci_sock.c
> +++ b/net/bluetooth/hci_sock.c
> @@ -46,9 +46,9 @@ struct hci_pinfo {
> 	unsigned short    channel;
> };
> 
> -static inline int hci_test_bit(int nr, void *addr)
> +static inline int hci_test_bit(int nr, const void *addr)
> {
> -	return *((__u32 *) addr + (nr >> 5)) & ((__u32) 1 << (nr & 31));
> +	return *((const __u32 *) addr + (nr >> 5)) & ((__u32) 1 << (nr & 31));
> }

we had a lengthy discussion about this before. I am reluctant to change any of this until we have a test tool that proofs this does not break userspace API compatibility.

I don't see how just adding const would break anything, but I cautious since this code is pretty much a big mistake that we are carrying around for almost 14 years now.

Regards

Marcel

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