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scsi: sg: Use mult_frac, drop MULDIV macro 

The MULDIV macro is essentially a duplicate of the more standard
mult_frac macro. Replace use of MULDIV with mult_frac & drop the
duplication.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Paul Burton 2016-08-19 17:43:57 +01:00 committed by Martin K. Petersen
parent b9b6e80ad3
commit f8630bd7e2
1 changed files with 4 additions and 15 deletions
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19
drivers/scsi/sg.c
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@ -79,18 +79,7 @@ static void sg_proc_cleanup(void);
*/
#define SG_MAX_CDB_SIZE 252
/*
* Suppose you want to calculate the formula muldiv(x,m,d)=int(x * m / d)
* Then when using 32 bit integers x * m may overflow during the calculation.
* 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))
#define SG_DEFAULT_TIMEOUT MULDIV(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
#define SG_DEFAULT_TIMEOUT mult_frac(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
int sg_big_buff = SG_DEF_RESERVED_SIZE;
/* N.B. This variable is readable and writeable via
@ -884,11 +873,11 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
return result;
if (val < 0)
return -EIO;
if (val >= MULDIV((s64)INT_MAX, USER_HZ, HZ))
val = min_t(s64, MULDIV((s64)INT_MAX, USER_HZ, HZ),
if (val >= mult_frac((s64)INT_MAX, USER_HZ, HZ))
val = min_t(s64, mult_frac((s64)INT_MAX, USER_HZ, HZ),
INT_MAX);
sfp->timeout_user = val;
sfp->timeout = MULDIV (val, HZ, USER_HZ);
sfp->timeout = mult_frac(val, HZ, USER_HZ);
return 0;
case SG_GET_TIMEOUT: /* N.B. User receives timeout as return value */