On Mon, Oct 24, 2016 at 10:47:54PM +0300, Julian Anastasov wrote: > > Hello, > > On Mon, 24 Oct 2016, Arnd Bergmann wrote: > > > Building the ip_vs_sync code with CONFIG_OPTIMIZE_INLINING on x86 > > confuses the compiler to the point where it produces a rather > > dubious warning message: > > > > net/netfilter/ipvs/ip_vs_sync.c:1073:33: error: ‘opt.init_seq’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > > struct ip_vs_sync_conn_options opt; > > ^~~ > > net/netfilter/ipvs/ip_vs_sync.c:1073:33: error: ‘opt.delta’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > > net/netfilter/ipvs/ip_vs_sync.c:1073:33: error: ‘opt.previous_delta’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > > net/netfilter/ipvs/ip_vs_sync.c:1073:33: error: ‘*((void *)&opt+12).init_seq’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > > net/netfilter/ipvs/ip_vs_sync.c:1073:33: error: ‘*((void *)&opt+12).delta’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > > net/netfilter/ipvs/ip_vs_sync.c:1073:33: error: ‘*((void *)&opt+12).previous_delta’ may be used uninitialized in this function [-Werror=maybe-uninitialized] > > > > The problem appears to be a combination of a number of factors, including > > the __builtin_bswap32 compiler builtin being slightly odd, having a large > > amount of code inlined into a single function, and the way that some > > functions only get partially inlined here. > > > > I've spent way too much time trying to work out a way to improve the > > code, but the best I've come up with is to add an explicit memset > > right before the ip_vs_seq structure is first initialized here. When > > the compiler works correctly, this has absolutely no effect, but in the > > case that produces the warning, the warning disappears. > > > > In the process of analysing this warning, I also noticed that > > we use memcpy to copy the larger ip_vs_sync_conn_options structure > > over two members of the ip_vs_conn structure. This works because > > the layout is identical, but seems error-prone, so I'm changing > > this in the process to directly copy the two members. This change > > seemed to have no effect on the object code or the warning, but > > it deals with the same data, so I kept the two changes together. > > > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > > OK, > > Acked-by: Julian Anastasov <ja@xxxxxx> > > I guess, Simon will take the patch for ipvs-next. @Simon: If you have no more pending updates, I can save you one pull request for this small fix by placing this. Thanks! -- To unsubscribe from this list: send the line "unsubscribe lvs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
