2014-12-21 17:04:40

by Chris Rorvick

Subject: [PATCH v3 0/2] lprocfs_write_frac_u64_helper cleanup

Added Andreas as reviewer (thanks!)

v2:

Added a second patch to address Dan Carpenter's concern with the
complexity of passing the sign through `mult'. Compile tested only.

Chris Rorvick (2):
drivers: staging: lustre: Use mult if units not specified
drivers: staging: lustre: Track sign separately

drivers/staging/lustre/lustre/obdclass/lprocfs_status.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

--
2.1.0

2014-12-21 17:04:54

by Chris Rorvick

Subject: [PATCH v3 2/2] drivers: staging: lustre: Track sign separately

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 <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
---
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 a7b270e..22e13f0 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -1862,6 +1862,7 @@ 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;
@@ -1872,7 +1873,7 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned long count,
kernbuf[count] = '\0';
pbuf = kernbuf;
if (*pbuf == '-') {
- mult = -mult;
+ sign = -1;
pbuf++;
}

@@ -1909,11 +1910,11 @@ 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

2014-12-21 17:04:53

by Chris Rorvick

Subject: [PATCH v3 1/2] drivers: staging: lustre: Use mult if units not specified

Units can be passed to lprocfs_write_frac_u64_helper() via a suffix
(e.g., "...K", "...M", etc.) tacked onto the value. A comment states
that "specified units override the multiplier," though the multiplier is
overridden regardless. Update the conditional logic so that it only
applies when units are specified.

Signed-off-by: Chris Rorvick <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
---
drivers/staging/lustre/lustre/obdclass/lprocfs_status.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index 3b7dfc3..a7b270e 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -1908,7 +1908,7 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned long count,
units <<= 10;
}
/* Specified units override the multiplier */
- if (units)
+ if (units > 1)
mult = mult < 0 ? -units : units;

frac *= mult;
--
2.1.0