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

[Hongzhi, Song]

On 4/24/19 9:47 AM, Bruce Ashfield wrote:
>
>
> On Tue, Apr 23, 2019 at 9:35 PM Hongzhi, Song 
> <hongzhi.song at windriver.com <mailto: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.


Ok, thanks.

--Hongzhi


>
> Bruce
>
>     --Hongzhi
>
>
>
>>
>>     Bruce
>>
>>     On Mon, Apr 22, 2019 at 11:20 PM Hongzhi, Song
>>     <hongzhi.song at windriver.com <mailto: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
>>         <mailto: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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