4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Matthias Kaehlcke <mka@xxxxxxxxxxxx> commit 93f56de259376d7e4fff2b2d104082e1fa66e237 upstream. When clang detects a non-boolean constant in a logical operation it generates a 'constant-logical-operand' warning. In ieee80211_try_rate_control_ops_get() the result of strlen(<const str>) is used in a logical operation, clang resolves the expression to an (integer) constant at compile time when clang's builtin strlen function is used. Change the condition to check for strlen() > 0 to make the constant operand boolean and thus avoid the warning. Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Cc: Nathan Chancellor <natechancellor@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/mac80211/rate.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/net/mac80211/rate.c +++ b/net/mac80211/rate.c @@ -173,9 +173,11 @@ ieee80211_rate_control_ops_get(const cha /* try default if specific alg requested but not found */ ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo); - /* try built-in one if specific alg requested but not found */ - if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT)) + /* Note: check for > 0 is intentional to avoid clang warning */ + if (!ops && (strlen(CONFIG_MAC80211_RC_DEFAULT) > 0)) + /* try built-in one if specific alg requested but not found */ ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT); + kernel_param_unlock(THIS_MODULE); return ops;