From: Arnd Bergmann arnd@arndb.de
[ Upstream commit 1d8d4af4347420d657be448f8be4c39c558f3b5d ]
gcc-9 triggers a false-postive warning in ieee80211_mlo_multicast_tx() for u32_encode_bits(ffs(links) - 1, ...), since ffs() can return zero on an empty bitmask, and the negative argument to u32_encode_bits() is then out of range:
In file included from include/linux/ieee80211.h:21, from include/net/cfg80211.h:23, from net/mac80211/tx.c:23: In function 'u32_encode_bits', inlined from 'ieee80211_mlo_multicast_tx' at net/mac80211/tx.c:4437:17, inlined from 'ieee80211_subif_start_xmit' at net/mac80211/tx.c:4485:3: include/linux/bitfield.h:177:3: error: call to '__field_overflow' declared with attribute error: value doesn't fit into mask 177 | __field_overflow(); \ | ^~~~~~~~~~~~~~~~~~ include/linux/bitfield.h:197:2: note: in expansion of macro '____MAKE_OP' 197 | ____MAKE_OP(u##size,u##size,,) | ^~~~~~~~~~~ include/linux/bitfield.h:200:1: note: in expansion of macro '__MAKE_OP' 200 | __MAKE_OP(32) | ^~~~~~~~~
Newer compiler versions do not cause problems with the zero argument because they do not consider this a __builtin_constant_p(). It's also harmless since the hweight16() check already guarantees that this cannot be 0.
Replace the ffs() with an equivalent find_first_bit() check that matches the later for_each_set_bit() style and avoids the warning.
Fixes: 963d0e8d08d9 ("wifi: mac80211: optionally implement MLO multicast TX") Signed-off-by: Arnd Bergmann arnd@arndb.de Link: https://lore.kernel.org/r/20230214132025.1532147-1-arnd@kernel.org Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/mac80211/tx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 6409097a56c7a..55220e764de68 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -4395,7 +4395,7 @@ static void ieee80211_mlo_multicast_tx(struct net_device *dev, u32 ctrl_flags = IEEE80211_TX_CTRL_MCAST_MLO_FIRST_TX;
if (hweight16(links) == 1) { - ctrl_flags |= u32_encode_bits(ffs(links) - 1, + ctrl_flags |= u32_encode_bits(find_first_bit(&links, 16) - 1, IEEE80211_TX_CTRL_MLO_LINK);
__ieee80211_subif_start_xmit(skb, sdata->dev, 0, ctrl_flags,