Messages in this thread | | | Date | Wed, 30 Nov 2022 16:06:19 +0100 | From | Petr Mladek <> | Subject | Re: [PATCH v2 3/3] power: process: use explicit levels for printk continuations |
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On Fri 2022-11-25 21:41:55, Thomas Weißschuh wrote: > On 2022-11-25 11:53-0800, Joe Perches wrote: > > On Fri, 2022-11-25 at 20:09 +0100, Thomas Weißschuh wrote: > >> Many of the printk messages emitted during suspend and resume are > >> emitted in fragments using pr_cont()/KERN_CONT. > >> > >> As during suspend and resume a lot of operations are happing in the > >> kernel the chances are high that the fragments are interspersed with > >> unrelated messages. > >> > >> In this case if no explicit level is specified for the fragments the > >> standard level is applied, which by default is KERN_WARNING. > >> > >> If the user is only observing KERN_WARNING and *not* KERN_INFO messages > >> they will see incomplete message fragments. > >> > >> By specifing the correct printk level also with the continuations this > >> mismatch can be avoided. > >> Also it reduces the amount of false-positive KERN_WARNING messages. > >> > >> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> > >> --- > >> kernel/power/process.c | 18 +++++++++--------- > >> 1 file changed, 9 insertions(+), 9 deletions(-) > >> > >> diff --git a/kernel/power/process.c b/kernel/power/process.c > > [] > >> @@ -82,7 +82,7 @@ static int try_to_freeze_tasks(bool user_only) > >> elapsed_msecs = ktime_to_ms(elapsed); > >> > >> if (todo) { > >> - pr_cont("\n"); > >> + pr_info_cont("\n"); > > > > I think this isn't needed because of the immediately following pr_err.
Great catch.
> The pr_cont() itself or the conversion to pr_info_cont() is not needed?
The pr_cont() was needed before the commit 4bcc595ccd80decb42450 ("printk: reinstate KERN_CONT for printing continuation lines").
Before this commit, lines were appended even without KERN_CONT when the previous line did not end with "\n".
The above commit caused that only lines with KERN_CONT will be appended.
We have the code:
pr_cont("\n"); pr_err("Freezing of tasks %s after %d.%03d seconds "
The pr_cont() is not needed here because pr_err() does not have KERN_CONT. It will always start on a new line.
> Personally I would prefer to keep the patch as is. > > If only the conversion is not needed for consistency with the rest of the file. > If the pr_cont() in general is not needed it should be changed in a dedicated > patch (by somebody who knows this code better).
I agree that it should be removed in a separate patch. The commit message should mention the commit that modified the KERN_CONT handling.
Best Regards, Petr
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