From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Perches Subject: Re: [PATCH v2] net: bluetooth: hci_sock: Use 'const void *' instead of 'void *' for 2nd parameter of hci_test_bit() Date: Mon, 02 Feb 2015 13:20:17 -0800 Message-ID: <1422912017.30476.28.camel@perches.com> References: <54CFE8BE.5030700@sunrus.com.cn> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: marcel-kz+m5ild9QBg9hUCZPvPmw@public.gmane.org, gustavo-THi1TnShQwVAfugRpC6u6w@public.gmane.org, johan.hedberg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, "David S. Miller" , linux-bluetooth-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" To: Chen Gang S Return-path: In-Reply-To: <54CFE8BE.5030700-/B7AUNIrSHOPt1CcHtbs0g@public.gmane.org> Sender: linux-bluetooth-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On Tue, 2015-02-03 at 05:14 +0800, Chen Gang S wrote: > hci_test_bit() does not modify 2nd parameter, so it is better to let it > be constant, or may cause build warning. The related warning (with > allmodconfig under xtensa): [] > diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c [] > @@ -46,7 +46,7 @@ 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)); > } It's probably better to use const __u32 * here too, but the real thing I wonder is whether or not there's an issue with one of the 2 uses of this function. One of them passes a unsigned long *, the other a u32 *. $ git grep -w hci_test_bit net/bluetooth/hci_sock.c:static inline int hci_test_bit(int nr, void *addr) net/bluetooth/hci_sock.c: if (!hci_test_bit(flt_event, &flt->event_mask)) net/bluetooth/hci_sock.c: !hci_test_bit(ocf & HCI_FLT_OCF_BITS, net/bluetooth/hci_sock.c- &hci_sec_filter.ocf_mask[ogf])) && hci_sec_filter.ocf_mask is __u32 but flt->event_mask is unsigned long. Any possible issue here on 64-bit systems? --- $ git grep -A4 "struct hci_filter {" include/net/bluetooth/hci_sock.h:struct hci_filter { include/net/bluetooth/hci_sock.h- unsigned long type_mask; include/net/bluetooth/hci_sock.h- unsigned long event_mask[2]; include/net/bluetooth/hci_sock.h- __le16 opcode; include/net/bluetooth/hci_sock.h-}; --- static bool is_filtered_packet(struct sock *sk, struct sk_buff *skb) { struct hci_filter *flt; [...] if (!hci_test_bit(flt_event, &flt->event_mask)) return true;