On 08/07/2017 08:19 PM, Sergey Senozhatsky wrote:
> 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?
Done.
>
> [..]
>> + 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.
I can't think of anything better than 'invalid timestamp option'. If you find
that confusing, please explain why.
>
>
>> + } 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.
Changed to 'timestamp can only e set to 0, disabled, or <string>'.
>
>
>> + return -EINVAL;
>> + }
>> +
>> + printk_time = _printk_time;
>> + pr_info("printk: timestamp set to %s\n", printk_time_str[printk_time]);
>
> ditto.
I don't find this confusing _at all_. Please offer an explanation of why you
think that message is confusing.
>
>
> [..]
>
>> +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...
See previous suggestion from peterz to switch to a fn ptr.
>
>> +static int printk_time;
>> +static int printk_time_setting;
>
> how about s/printk_time_setting/printk_time_source/? or something similar?
Sure.
P.
>
> -ss
>
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