Re: [PATCH v2] printk: Do not lose last line in kmsg buffer dump

From: Sergey Senozhatsky
Date: Fri Jul 12 2019 - 05:23:00 EST


On (07/12/19 11:12), Petr Mladek wrote:
> > For example, with the following two final prints:
> >
> > [ 6.427502] AAAAAAAAAAAAA
> > [ 6.427769] BBBBBBBB12345
> >
> > A dump of a 64-byte buffer filled by kmsg_dump_get_buffer(), before this
> > patch:
> >
> > 00000000: 3c 30 3e 5b 20 20 20 20 36 2e 35 32 32 31 39 37 <0>[ 6.522197
> > 00000010: 5d 20 41 41 41 41 41 41 41 41 41 41 41 41 41 0a ] AAAAAAAAAAAAA.
> > 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> >
> > After this patch:
> >
> > 00000000: 3c 30 3e 5b 20 20 20 20 36 2e 34 35 36 36 37 38 <0>[ 6.456678
> > 00000010: 5d 20 42 42 42 42 42 42 42 42 31 32 33 34 35 0a ] BBBBBBBB12345.
> > 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> > 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> >
> > Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
>
> I think that I need vacation. I have got lost in all the checks
> and got it wrongly in the morning.
>
> This patch fixes the calculation of messages that might fit
> into the buffer. It makes sure that the function that writes
> the messages will really allow to write them.
>
> It seems to be the correct fix.
>
> Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>

Looks correct to me as well.

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>

-ss