From fdf2f40c6cb9649e3990bc11fe0b5c155adf555a Mon Sep 17 00:00:00 2001 From: Surendra Patil Date: Mon, 3 Feb 2014 21:53:53 -0800 Subject: [PATCH] staging: rtl8821ae: Fixed the size of array to macro as discussed by Linus MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Linus Torvalds writes: It causes an interesting warning for me: drivers/staging/rtl8821ae/rtl8821ae/dm.c: In function ‘rtl8821ae_dm_clear_txpower_tracking_state’: drivers/staging/rtl8821ae/rtl8821ae/dm.c:487:31: warning: iteration 2u invokes undefined behavior [-Waggressive-loop-optimizations] rtldm->bb_swing_idx_ofdm[p] = rtldm->default_ofdm_index; ^ drivers/staging/rtl8821ae/rtl8821ae/dm.c:485:2: note: containing loop for (p = RF90_PATH_A; p < MAX_RF_PATH; ++p) { ^ and gcc is entirely correct: that loop iterates from 0 to 3, and does this: rtldm->bb_swing_idx_ofdm[p] = rtldm->default_ofdm_index; but the bb_swing_idx_ofdm[] array only has two members. So the last two iterations will overwrite bb_swing_idx_ofdm_current and the first entry in bb_swing_idx_ofdm_base[]. Now, the bug does seem to be benign: bb_swing_idx_ofdm_current isn't actually ever *used* as far as I can tell, and the first entry of bb_swing_idx_ofdm_base[] will have been written with that same "rtldm->default_ofdm_index" value. But gcc is absolutely correct, and that driver needs fixing. I've pulled it and will let it be because it doesn't seem to be an issue in practice, but please fix it. The obvious fix would seem to change the size of "2" to be "MAX_RF_PATH", but I'll abstain from doing those kinds of changes in the merge when it doesn't seem to affect the build or functionality). Reported-By: Linus Torvalds Signed-off-by: Surendra Patil Signed-off-by: Greg Kroah-Hartman --- drivers/staging/rtl8821ae/wifi.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/staging/rtl8821ae/wifi.h b/drivers/staging/rtl8821ae/wifi.h index cfe88a1efd55..76bef93ad70a 100644 --- a/drivers/staging/rtl8821ae/wifi.h +++ b/drivers/staging/rtl8821ae/wifi.h @@ -1414,7 +1414,7 @@ struct rtl_dm { /*88e tx power tracking*/ - u8 bb_swing_idx_ofdm[2]; + u8 bb_swing_idx_ofdm[MAX_RF_PATH]; u8 bb_swing_idx_ofdm_current; u8 bb_swing_idx_ofdm_base[MAX_RF_PATH]; bool bb_swing_flag_Ofdm; -- 2.45.2