On Tue, May 5, 2020 at 10:07 PM Jason A. Donenfeld <Jason@xxxxxxxxx> wrote: > On Tue, May 5, 2020 at 8:13 AM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > clang points out a harmless use of uninitialized variables that > > get passed into a local function but are ignored there: > > > > In file included from drivers/net/wireguard/ratelimiter.c:223: > > drivers/net/wireguard/selftest/ratelimiter.c:173:34: error: variable 'skb6' is uninitialized when used here [-Werror,-Wuninitialized] > > ret = timings_test(skb4, hdr4, skb6, hdr6, &test_count); > > ^~~~ > > drivers/net/wireguard/selftest/ratelimiter.c:123:29: note: initialize the variable 'skb6' to silence this warning > > struct sk_buff *skb4, *skb6; > > ^ > > = NULL > > drivers/net/wireguard/selftest/ratelimiter.c:173:40: error: variable 'hdr6' is uninitialized when used here [-Werror,-Wuninitialized] > > ret = timings_test(skb4, hdr4, skb6, hdr6, &test_count); > > ^~~~ > > drivers/net/wireguard/selftest/ratelimiter.c:125:22: note: initialize the variable 'hdr6' to silence this warning > > struct ipv6hdr *hdr6; > > ^ > > Seems like the code is a bit easier to read and is more uniform > looking by just initializing those two variables to NULL, like the > warning suggests. If you don't mind, I'll queue something up in my > tree to this effect. I think we really should fix clang to not make this suggestion, as that normally leads to worse code ;-) The problem with initializing variables to NULL (or 0) is that it hides real bugs when the NULL initialization end up being used in a place where a non-NULL value is required, so I try hard not to send patches that add those. It's your code though, so if you prefer to do it that way, just do that and add me as "Reported-by:" > By the way, I'm having a bit of a hard time reproducing the warning > with either clang-10 or clang-9. Just for my own curiosity, would you > mind sending the .config that results in this? See https://pastebin.com/6zRSUYax Arnd
