When the configuration parameter CONFIG_HZ is less that 100, the compiler
generates an error as follows:
../drivers/staging/rtl8192e/rtllib_wx.c: In function 'rtl819x_translate_scan':
../drivers/staging/rtl8192e/rtllib_wx.c:220:57: warning: division by zero
[-Wdiv-by-zero]
220 | (jiffies - network->last_scanned) / (HZ / 100));
| ^
In file included from ../include/linux/skbuff.h:45,
from ../include/linux/if_ether.h:19,
from ../include/linux/etherdevice.h:20,
from ../drivers/staging/rtl8192e/rtllib_wx.c:18:
../drivers/staging/rtl8192e/rtllib_wx.c: In function 'rtllib_wx_get_scan':
../drivers/staging/rtl8192e/rtllib_wx.c:261:70: warning: division by zero
[-Wdiv-by-zero]
261 | (jiffies - network->last_scanned) /
|
In fact, is HZ is not a multiple of 100, the calculation will be wrong, but it
will compile correctly.
The fix is to get rid of the (HZ / 100) portion. To decrease any round-off
errors, the compiler is forced to perform the 100 * jiffies-difference before
dividing by HX. This patch is only compile tested.
Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
---
drivers/staging/rtl8192e/rtllib_wx.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/rtl8192e/rtllib_wx.c
b/drivers/staging/rtl8192e/rtllib_wx.c
index da2c41c9b92f..7013425102dd 100644
--- a/drivers/staging/rtl8192e/rtllib_wx.c
+++ b/drivers/staging/rtl8192e/rtllib_wx.c
@@ -217,7 +217,7 @@ static inline char *rtl819x_translate_scan(struct
rtllib_device *ieee,
p = custom;
p += scnprintf(p, MAX_CUSTOM_LEN - (p - custom),
" Last beacon: %lums ago",
- (jiffies - network->last_scanned) / (HZ / 100));
+ (100 *(jiffies - network->last_scanned)) / HZ);
iwe.u.data.length = p - custom;
if (iwe.u.data.length)
start = iwe_stream_add_point_rsl(info, start, stop,
@@ -258,8 +258,8 @@ int rtllib_wx_get_scan(struct rtllib_device *ieee,
escape_essid(network->ssid,
network->ssid_len),
network->bssid,
- (jiffies - network->last_scanned) /
- (HZ / 100));
+ (100 * (jiffies - network->last_scanned)) /
+ HZ);
}
spin_unlock_irqrestore(&ieee->lock, flags);
