[linux-yocto] [linux-yocto-rt][PATCH] printk: revert part of code of printk emergency mechanism

[Bruce Ashfield]

On Tue, Apr 23, 2019 at 9:35 PM Hongzhi, Song <hongzhi.song at windriver.com>
wrote:

>
> On 4/24/19 4:04 AM, Bruce Ashfield wrote:
>
> Since this is still being discussed on the -rt mailing list, I'm going to
> wait to see how that shakes out before merging the change.
>
>
> Yes, but it seems like that upstream won't fix the issue in a short time.
>

but also described it as a feature, not a bug :D
.. so I'm inclined to keep the behaviour of our -rt consistent with the
upstream
series, unless this is causing a lot of issues.

Bruce



> --Hongzhi
>
>
>
>
> Bruce
>
> On Mon, Apr 22, 2019 at 11:20 PM Hongzhi, Song <hongzhi.song at windriver.com>
> wrote:
>
>> Please merge to v5.0/standard/preempt-rt/base and
>> v5.0/standard/preempt-rt/intel-x86
>>
>>
>> --Hongzhi
>>
>>
>> On 4/23/19 11:14 AM, Hongzhi.Song wrote:
>> > Two commits from rt-kernel cause the following disorder log at the
>> > early stage of boot with qemux86-64. Maybe it has other disorder logs
>> > which I omit.
>> >
>> > Commits:
>> > 7128a815: printk: introduce emergency messages
>> > b9d460e4: serial: 8250: implement write_atomic
>> >
>> > [    0.401166] 000: 6200.04 BogoMIPS (lpj=3100023)
>> > [    0.877953] 000: Intel(R) Core(TM)2 Duo CPU     T7700  @ 2.40GHz
>> > [    0.877953] 000:  (family: 0x6, model: 0xf
>> > [    0.877953] 000: , stepping: 0xb)
>> > [    1.255009] 000:  5
>> > [    1.255167] 000:  *10
>> > [    1.255295] 000:  11
>> > [    1.255406] 000: )
>> >
>> > Obviously, the printk emergency mechanism doesn't work as expected.
>> > Removing partial code of printk emergency mechanism can
>> > fix the issue temporarily.
>> >
>> > Signed-off-by: Hongzhi.Song <hongzhi.song at windriver.com>
>> > ---
>> >   kernel/printk/printk.c | 4 ++++
>> >   1 file changed, 4 insertions(+)
>> >
>> > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
>> > index 997d07b..99d4a94 100644
>> > --- a/kernel/printk/printk.c
>> > +++ b/kernel/printk/printk.c
>> > @@ -1726,6 +1726,7 @@ static void call_console_drivers(u64 seq, const
>> char *ext_text, size_t ext_len,
>> >                       con->wrote_history = 1;
>> >                       con->printk_seq = seq - 1;
>> >               }
>> > +#if 0
>> >               if (con->write_atomic && level <
>> emergency_console_loglevel &&
>> >                   facility == 0) {
>> >                       /* skip emergency messages, already printed */
>> > @@ -1733,6 +1734,7 @@ static void call_console_drivers(u64 seq, const
>> char *ext_text, size_t ext_len,
>> >                               con->printk_seq = seq;
>> >                       continue;
>> >               }
>> > +#endif
>> >               if (con->flags & CON_BOOT && facility == 0) {
>> >                       /* skip emergency messages, already printed */
>> >                       if (con->printk_seq < seq)
>> > @@ -3134,10 +3136,12 @@ static void call_emergency_console_drivers(int
>> level, const char *text,
>> >       for_each_console(con) {
>> >               if (!(con->flags & CON_ENABLED))
>> >                       continue;
>> > +#if 0
>> >               if (con->write_atomic && level <
>> emergency_console_loglevel) {
>> >                       con->write_atomic(con, text, text_len);
>> >                       continue;
>> >               }
>> > +#endif
>> >               if (con->write && (con->flags & CON_BOOT)) {
>> >                       con->write(con, text, text_len);
>> >                       continue;
>>
>
>
> --
> - Thou shalt not follow the NULL pointer, for chaos and madness await thee
> at its end
> - "Use the force Harry" - Gandalf, Star Trek II
>
>

-- 
- Thou shalt not follow the NULL pointer, for chaos and madness await thee
at its end
- "Use the force Harry" - Gandalf, Star Trek II
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