Return-Path: Message-ID: <54D0332B.6050701@sunrus.com.cn> Date: Tue, 03 Feb 2015 10:32:11 +0800 From: Chen Gang S MIME-Version: 1.0 To: Joe Perches CC: marcel@holtmann.org, gustavo@padovan.org, johan.hedberg@gmail.com, "David S. Miller" , linux-bluetooth@vger.kernel.org, "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v2] net: bluetooth: hci_sock: Use 'const void *' instead of 'void *' for 2nd parameter of hci_test_bit() References: <54CFE8BE.5030700@sunrus.com.cn> <1422912017.30476.28.camel@perches.com> In-Reply-To: <1422912017.30476.28.camel@perches.com> Content-Type: text/plain; charset=windows-1252 List-ID: On 2/3/15 05:20, Joe Perches wrote: > 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? > For me, it can not cause issue on 64-bit systems. hci_test_bit() treats 'addr' as "__u32 *", and has to use the pointer to do something. Thanks. -- Chen Gang Open, share, and attitude like air, water, and life which God blessed