Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH 5/9] ipv4: tcp_output: avoid warning about NET_ADD_STATS | Date | Thu, 28 Mar 2024 15:30:43 +0100 |
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From: Arnd Bergmann <arnd@arndb.de>
Clang warns about a range check in percpu_add_op() being impossible to hit for an u8 variable:
net/ipv4/tcp_output.c:188:3: error: result of comparison of constant -1 with expression of type 'u8' (aka 'unsigned char') is always false [-Werror,-Wtautological-constant-out-of-range-compare] NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/net/ip.h:291:41: note: expanded from macro 'NET_ADD_STATS' #define NET_ADD_STATS(net, field, adnd) SNMP_ADD_STATS((net)->mib.net_statistics, field, adnd) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/net/snmp.h:143:4: note: expanded from macro 'SNMP_ADD_STATS' this_cpu_add(mib->mibs[field], addend) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/percpu-defs.h:509:33: note: expanded from macro 'this_cpu_add' #define this_cpu_add(pcp, val) __pcpu_size_call(this_cpu_add_, pcp, val) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all) <scratch space>:187:1: note: expanded from here this_cpu_add_8 ^ arch/x86/include/asm/percpu.h:326:35: note: expanded from macro 'this_cpu_add_8' #define this_cpu_add_8(pcp, val) percpu_add_op(8, volatile, (pcp), val) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/x86/include/asm/percpu.h:127:31: note: expanded from macro 'percpu_add_op' ((val) == 1 || (val) == -1)) ? \ ~~~~~ ^ ~~
Avoid this warning with a cast to a signed 'int'.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- net/ipv4/tcp_output.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index e3167ad96567..dbe54fceee08 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -183,7 +183,7 @@ static inline void tcp_event_ack_sent(struct sock *sk, u32 rcv_nxt) if (unlikely(tp->compressed_ack)) { NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, - tp->compressed_ack); + (int)tp->compressed_ack); tp->compressed_ack = 0; if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) __sock_put(sk); -- 2.39.2
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