Evolution-X-Devices/kernel_realme_salaa
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

UPSTREAM: cgroup: add cgroup_parse_float()

Browse Source 
cgroup already uses floating point for percent[ile] numbers and there
are several controllers which want to take them as input.  Add a
generic parse helper to handle inputs.

Update the interface convention documentation about the use of
percentage numbers.  While at it, also clarify the default time unit.

Bug: 120440300
Signed-off-by: Tejun Heo <tj@kernel.org>
(cherry picked from commit a5e112e6424adb77d953eac20e6936b952fd6b32)
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Change-Id: Ic1fcf21d7955eb8edd2e8e91517bca6aef41694f
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Naveen <133593113+elohim-etz@users.noreply.github.com>
This commit is contained in:
Tejun Heo
2019-05-13 12:37:17 -07:00
committed by Ansh
parent 7b1f20db92
commit c6fa9f201a
2 changed files with 45 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/cgroup.h
View File

@@ -130,6 +130,8 @@ void cgroup_free(struct task_struct *p);
int cgroup_init_early(void);
int cgroup_init(void);
int cgroup_parse_float(const char *input, unsigned dec_shift, s64 *v);
/*
* Iteration helpers and macros.
*/

43
kernel/cgroup/cgroup.c
View File

@@ -6360,4 +6360,47 @@ static int __init cgroup_sysfs_init(void)
return sysfs_create_group(kernel_kobj, &cgroup_sysfs_attr_group);
}
subsys_initcall(cgroup_sysfs_init);
static u64 power_of_ten(int power)
{
u64 v = 1;
while (power--)
v *= 10;
return v;
}
/**
* cgroup_parse_float - parse a floating number
* @input: input string
* @dec_shift: number of decimal digits to shift
* @v: output
*
* Parse a decimal floating point number in @input and store the result in
* @v with decimal point right shifted @dec_shift times. For example, if
* @input is "12.3456" and @dec_shift is 3, *@v will be set to 12345.
* Returns 0 on success, -errno otherwise.
*
* There's nothing cgroup specific about this function except that it's
* currently the only user.
*/
int cgroup_parse_float(const char *input, unsigned dec_shift, s64 *v)
{
s64 whole, frac = 0;
int fstart = 0, fend = 0, flen;
if (!sscanf(input, "%lld.%n%lld%n", &whole, &fstart, &frac, &fend))
return -EINVAL;
if (frac < 0)
return -EINVAL;
flen = fend > fstart ? fend - fstart : 0;
if (flen < dec_shift)
frac *= power_of_ten(dec_shift - flen);
else
frac = DIV_ROUND_CLOSEST_ULL(frac, power_of_ten(flen - dec_shift));
*v = whole * power_of_ten(dec_shift) + frac;
return 0;
}
#endif /* CONFIG_SYSFS */