Messages in this thread | | | Date | Tue, 22 Jul 2014 06:48:22 -0500 | From | Alex Elder <> | Subject | Re: [PATCH v5 3/7] printk: initialize syslog_prev and console_prev |
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On 07/21/2014 08:02 AM, Alex Elder wrote: > Two global variables, "syslog_prev" and "console_prev", maintain a > copy of the flags value used in the log record most recently > formatted for syslog or the console, respectively. > > Initially there is no previous formatted log record, and these > variables simply have an initial value 0. And occasionally log > records can get consumed at a rate such that syslog or the console > can't keep up, in which case those variables (along with their > corresponding position variables) must be reset. Here too, they're > reset to 0. > > This patch changes it so the initial value used is LOG_NEWLINE. > That is, if we know nothing about the prevously-formatted log > record, we can assume it was complete, and ended with a newline. > One exception is that occasionally we reset our syslog or console > (etc.) position variables. In that case the previously-formatted > record flags value is still valid, so we preserve that information. > > This is being done to support the next patch. Initializing > these variables this way makes LOG_NEWLINE and LOG_CONT be > mutually exclusive, and the next patch uses that fact to simplify > some logic. > > Signed-off-by: Alex Elder <elder@linaro.org> > Reviewed-by: Petr Mládek <pmladek@suse.cz>
I have one change I'd like to suggest on this one.
Petr, could you offer your opinion?
> --- > kernel/printk/printk.c | 44 ++++++++++++++++++++++++++++++-------------- > 1 file changed, 30 insertions(+), 14 deletions(-) > > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index 9f11eab..2f43116 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c
. . .
> @@ -2156,10 +2168,14 @@ again: > "%s** %u printk messages dropped **\n", > (console_prev & LOG_CONT) ? "\n" : "", > (unsigned)(log_first_seq - console_seq)); > - /* messages are gone, move to first one */ > + /* > + * Messages are gone, move to first one. > + * Don't discard what we know about the > + * previously-formatted record. > + */ > console_seq = log_first_seq; > console_idx = log_first_idx; > - console_prev = 0; > + console_prev &= LOG_NEWLINE|LOG_CONT;
In this one spot, I think console_prev should simply be initialized with LOG_NEWLINE.
The reason is that the "printk messages dropped" message will be inserted into the formatted output, and is hence the last formatted line. And that message is (now) terminated with a newline.
-Alex
> } else { > len = 0; > }
. . .
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