The MULDIV macro has been designed for small numbers.
Compiler emits an overflow warning on 64 bit systems.
This patch uses 64 bit numbers in order to suppress
warning.
Signed-off-by: Sinan Kaya <ok...@codeaurora.org>
---
drivers/scsi/sg.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 9d7b7db..112d8974 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -51,6 +51,7 @@ static int sg_version_num = 30536; /* 2 digits for each
component */
#include <linux/atomic.h>
#include <linux/ratelimit.h>
#include <linux/uio.h>
+#include <asm/div64.h>
#include "scsi.h"
#include <scsi/scsi_dbg.h>
@@ -85,12 +86,17 @@ static void sg_proc_cleanup(void);
* Replacing muldiv(x) by muldiv(x)=((x % d) * m) / d + int(x / d) * m
* calculates the same, but prevents the overflow when both m and d
* are "small" numbers (like HZ and USER_HZ).
- * Of course an overflow is inavoidable if the result of muldiv doesn't fit
- * in 32 bits.
*/
-#define MULDIV(X,MUL,DIV) ((((X % DIV) * MUL) / DIV) + ((X / DIV) * MUL))
+static inline u64 mult_frac64(u64 x, u32 numer, u32 denom)
+{
+ u64 r1 = do_div(x, denom);
+ u64 r2 = r1 * numer;
+
+ do_div(r2, denom);
+ return (x * numer) + r2;
+}
-#define SG_DEFAULT_TIMEOUT MULDIV(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
+#define SG_DEFAULT_TIMEOUT mult_frac64(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
int sg_big_buff = SG_DEF_RESERVED_SIZE;
/* N.B. This variable is readable and writeable via
@@ -877,10 +883,10 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned
long arg)
return result;
if (val < 0)
return -EIO;
- if (val >= MULDIV (INT_MAX, USER_HZ, HZ))
- val = MULDIV (INT_MAX, USER_HZ, HZ);
+ if (val >= mult_frac64(INT_MAX, USER_HZ, HZ))
+ val = mult_frac64(INT_MAX, USER_HZ, HZ);
sfp->timeout_user = val;
- sfp->timeout = MULDIV (val, HZ, USER_HZ);
+ sfp->timeout = mult_frac64(val, HZ, USER_HZ);
return 0;
case SG_GET_TIMEOUT: /* N.B. User receives timeout as return value */
--
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project
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