Re: [libvirt] [PATCH] network: selectively disable -Wcast-align in virNetDevParseDadStatus

On 11/30/2015 09:18 PM, Jim Fehlig wrote: > On 11/26/2015 08:10 AM, Ian Campbell wrote: >> Commit 0f7436ca54c9 "network: wait for DAD to finish for bridge IPv6 addresses" >> results in: >> >> CC util/libvirt_util_la-virnetdevmacvlan.lo >> util/virnetdev.c: In function 'virNetDevParseDadStatus': >> util/virnetdev.c:1319:188: error: cast increases required alignment of target type [-Werror=cast-align] >> util/virnetdev.c:1332:41: error: cast increases required alignment of target type [-Werror=cast-align] >> util/virnetdev.c:1334:92: error: cast increases required alignment of target type [-Werror=cast-align] >> cc1: all warnings being treated as errors >> >> on at least ARM platforms. > Thanks for looking into this issue Ian. > >> The three macros involved (NLMSG_NEXT, IFA_RTA and RTA_NEXT) all appear to >> correctly take care of alignment, therefore suppress Wcast-align around their >> uses. > Indeed those macros seem to handle alignment, even on one of my older machines > with 2.6 kernel headers. IMO this falls under the "difficult or impossible to > address" scenarios that Daniel mentioned when introducing the VIR_WARNINGS_* > macros via commit e57aaa6f. Adding Daniel to cc for a sanity check of my weak ACK. Looks like I forgot to actually add Daniel to the cc list. Doing so now... > > Regards, > Jim > >> Signed-off-by: Ian Campbell <ian.campbell(a)citrix.com&gt; >> Cc: Maxim Perevedentsev <mperevedentsev(a)virtuozzo.com&gt; >> Cc: Laine Stump <laine(a)laine.org&gt; >> Cc: Dario Faggioli <dario.faggioli(a)citrix.com&gt; >> Cc: Jim Fehlig <jfehlig(a)suse.com&gt; >> --- >> src/util/virnetdev.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c >> index ade9afa..0bc809e 100644 >> --- a/src/util/virnetdev.c >> +++ b/src/util/virnetdev.c >> @@ -1316,7 +1316,10 @@ virNetDevParseDadStatus(struct nlmsghdr *nlh, int len, >> struct rtattr *rtattr_ptr; >> size_t i; >> struct in6_addr *addr; >> + >> + VIR_WARNINGS_NO_CAST_ALIGN >> for (; NLMSG_OK(nlh, len); nlh = NLMSG_NEXT(nlh, len)) { >> + VIR_WARNINGS_RESET >> if (NLMSG_PAYLOAD(nlh, 0) < sizeof(struct ifaddrmsg)) { >> /* Message without payload is the last one. */ >> break; >> @@ -1329,9 +1332,11 @@ virNetDevParseDadStatus(struct nlmsghdr *nlh, int len, >> } >> >> ifaddrmsg_len = IFA_PAYLOAD(nlh); >> + VIR_WARNINGS_NO_CAST_ALIGN >> rtattr_ptr = (struct rtattr *) IFA_RTA(ifaddrmsg_ptr); >> for (; RTA_OK(rtattr_ptr, ifaddrmsg_len); >> rtattr_ptr = RTA_NEXT(rtattr_ptr, ifaddrmsg_len)) { >> + VIR_WARNINGS_RESET >> if (RTA_PAYLOAD(rtattr_ptr) != sizeof(struct in6_addr)) { >> /* No address: ignore. */ >> continue;