[PATCH v2 2/2] drivers: staging: lustre: Track sign separately

Chris Rorvick
2014-12-17T04:24:49Z

The `mult' parameter is negated if the user data begins with a '-' so
that the final value has the appropriate sign. But `mult' is only used
if the user data does not include a "units" suffix. In this case,
`mult' is overridden with the numeric scale conveyed by the units suffix,
but retains the sign of the original value.

Having `mult' serving double-duty works but is confusing. Use a new
local variable to store the sign of the user data instead. This also
fixes a pitfall of passing 0 to `mult', expecting it to be ignored when
a units suffix is specified, but having the effect of taking the
absolute value of the user-provided data.

Signed-off-by: Chris Rorvick <chris@rorvick.com>
---
drivers/staging/lustre/lustre/obdclass/lprocfs_status.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index 92ed0a0..b6c3352 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -1864,6 +1864,7 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned long count,
char kernbuf[22], *end, *pbuf;
__u64 whole, frac = 0, units;
unsigned frac_d = 1;
+ int sign = 1;

if (count > (sizeof(kernbuf) - 1))
return -EINVAL;
@@ -1874,7 +1875,7 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned long count,
kernbuf[count] = '\0';
pbuf = kernbuf;
if (*pbuf == '-') {
- mult = -mult;
+ sign = -1;
pbuf++;
}

@@ -1911,11 +1912,11 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned long count,
}
/* Specified units override the multiplier */
if (units > 1)
- mult = mult < 0 ? -units : units;
+ mult = units;

frac *= mult;
do_div(frac, frac_d);
- *val = whole * mult + frac;
+ *val = sign * (whole * mult + frac);
return 0;
}
EXPORT_SYMBOL(lprocfs_write_frac_u64_helper);
--
2.1.0