lkml.org 
[lkml]   [2017]   [Aug]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4] printk: Add monotonic, boottime, and realtime timestamps
On (08/07/17 11:52), Prarit Bhargava wrote:
[..]
> +/**
> + * enum printk_time_type - Timestamp types for printk() messages.
> + * @PRINTK_TIME_DISABLE: No time stamp.
> + * @PRINTK_TIME_LOCAL: Local hardware clock timestamp.
> + * @PRINTK_TIME_BOOT: Boottime clock timestamp.
> + * @PRINTK_TIME_MONO: Monotonic clock timestamp.
> + * @PRINTK_TIME_REAL: Realtime clock timestamp. On 32-bit
> + * systems selecting the real clock printk timestamp may lead to unlikely
> + * situations where a timestamp is wrong because the real time offset is read
> + * without the protection of a sequence lock in the call to ktime_get_log_ts()
> + * in printk_get_ts() below.
> + */
> +enum printk_time_type {
> + PRINTK_TIME_DISABLE = 0,
> + PRINTK_TIME_LOCAL = 1,
> + PRINTK_TIME_BOOT = 2,
> + PRINTK_TIME_MONO = 3,
> + PRINTK_TIME_REAL = 4,
> +};

may be call the entire thing 'timestamp surces' or something?

[..]
> + if (strlen(param) == 1) {
> + /* Preserve legacy boolean settings */
> + if (!strcmp("0", param) || !strcmp("n", param) ||
> + !strcmp("N", param))
> + _printk_time = PRINTK_TIME_DISABLE;
> + if (!strcmp("1", param) || !strcmp("y", param) ||
> + !strcmp("Y", param))
> + _printk_time = PRINTK_TIME_LOCAL;
> + }
> + if (_printk_time == -1) {
> + for (stamp = 0; stamp <= 4; stamp++) {
> + if (!strncmp(printk_time_str[stamp], param,
> + strlen(param))) {
> + _printk_time = stamp;
> + break;
> + }
> + }
> + }

you can use match_string() here.

> + if (_printk_time == -1) {
> + pr_warn("printk: invalid timestamp value %s\n", param);
> + return -EINVAL;
> + }

`invalid timestamp value' is confusing.


> + } else if ((printk_time_setting != _printk_time) &&
> + (_printk_time != 0)) {
> + pr_warn("printk: timestamp can only be set to 0(disabled) or %s\n",
> + printk_time_str[printk_time_setting]);

ditto.


> + return -EINVAL;
> + }
> +
> + printk_time = _printk_time;
> + pr_info("printk: timestamp set to %s\n", printk_time_str[printk_time]);

ditto.


[..]

> +static u64 printk_get_ts(void)
> +{
> + u64 mono, offset_real;
> +
> + if (printk_time <= PRINTK_TIME_LOCAL)
> + return local_clock();
> +
> + if (printk_time == PRINTK_TIME_BOOT)
> + return ktime_get_boot_log_ts();
> +
> + mono = ktime_get_real_log_ts(&offset_real);
> +
> + if (printk_time == PRINTK_TIME_MONO)
> + return mono;
> +
> + return mono + offset_real;
> +}

this looks hard...

> +static int printk_time;
> +static int printk_time_setting;

how about s/printk_time_setting/printk_time_source/? or something similar?

-ss

\
 
 \ /
  Last update: 2017-08-08 02:19    [W:0.101 / U:0.020 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site