ath5k: avoid and warn on potential infinite loop

If we are trying to interpolate a curve with slope == 0, the return
value will always be the y-coordinate.  In this code we are looping
until we reach a minimum y-coordinate on a line, which in the 0-slope
case can never happen, thus the loop never terminates.

The PCDAC steps come from the EEPROM and should never be equal, but
we should gracefully handle that case, so warn and bail out.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/ath5k/phy.c b/drivers/net/wireless/ath/ath5k/phy.c
index d0d1c350025aebba1fe4e17a44550536a59951ba..a876ca8d69eff524926a0f39d68edd37c053306b 100644 (file)
--- a/drivers/net/wireless/ath/ath5k/phy.c
+++ b/drivers/net/wireless/ath/ath5k/phy.c
@@ -1897,6 +1897,9 @@ ath5k_get_linear_pcdac_min(const u8 *stepL, const u8 *stepR,
        s16 min_pwrL, min_pwrR;
        s16 pwr_i;
 
+       if (WARN_ON(stepL[0] == stepL[1] || stepR[0] == stepR[1]))
+               return 0;
+
        if (pwrL[0] == pwrL[1])
                min_pwrL = pwrL[0];
        else {