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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "John W. Linville" <linville@tuxdriver.com>,
        "Andrew Bresticker" <abrestic@chromium.org>
Date:   Wed, 28 Feb 2018 15:20:18 +0000
Message-ID: <lsq.1519831218.203403009@decadent.org.uk>
Subject: [PATCH 3.16 233/254] mac80211_hwsim: fix compiler warning on MIPS
In-Reply-To: <lsq.1519831217.271785318@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Bresticker <abrestic@chromium.org>

commit 5d26b50813ea6206a7bbab2e645e68044f101ac5 upstream.

The dividend in do_div() is expected to be an unsigned 64-bit integer,
which leads to the following warning when building for 32-bit MIPS:

  drivers/net/wireless/mac80211_hwsim.c: In function 'mac80211_hwsim_set_tsf':
  drivers/net/wireless/mac80211_hwsim.c:664:98: warning: comparison of distinct pointer types lacks a cast [enabled by default]
    data->bcn_delta = do_div(delta, bcn_int);

Since we care about the signedness of delta when adjusting tsf_offset
and bcm_delta, use the absolute value for the division and compare
the two timestamps to determine the sign.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/net/wireless/mac80211_hwsim.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -685,11 +685,16 @@ static void mac80211_hwsim_set_tsf(struc
 	struct mac80211_hwsim_data *data = hw->priv;
 	u64 now = mac80211_hwsim_get_tsf(hw, vif);
 	u32 bcn_int = data->beacon_int;
-	s64 delta = tsf - now;
+	u64 delta = abs64(tsf - now);
 
-	data->tsf_offset += delta;
 	/* adjust after beaconing with new timestamp at old TBTT */
-	data->bcn_delta = do_div(delta, bcn_int);
+	if (tsf > now) {
+		data->tsf_offset += delta;
+		data->bcn_delta = do_div(delta, bcn_int);
+	} else {
+		data->tsf_offset -= delta;
+		data->bcn_delta = -do_div(delta, bcn_int);
+	}
 }
 
 static void mac80211_hwsim_monitor_rx(struct ieee80211_hw *hw,