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

[Bruce Ashfield]

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.

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
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