Re: [PATCHSET] printk: implement printk_header() and merging printk

From: Randy Dunlap
Date: Tue Jan 15 2008 - 21:49:03 EST


On Wed, 16 Jan 2008 10:00:06 +0900 Tejun Heo wrote:

> Hello, all.
>
> This patchset implements printk_header() and mprintk - merging printk
> - to make printing multiline messages and assembling message
> piece-by-piece easier.
>
> In a nutshell, printk_header() lets you do the following atomically
> (against other messages).
>
> code:
+ printk_header(KERN_INFO "ata1.00: ", "line0\nline1\nline2\n");
>
> output:
> <6>ata1.00: line0
> <6> line1
> <6> line2
>
> And mprintk the following.
>
> code:
> DEFINE_MPRINTK(mp, 2 * 80);
>
> mprintk_set_header(&mp, KERN_INFO "ata%u.%2u: ", 1, 0);
> mprintk_push(&mp, "ATA %d", 7);
> mprintk_push(&mp, ", %u sectors\n", 1024);
> mprintk(&mp, "everything seems dandy\n");

Looks pretty good to me except that I would change mprintk_push to
mprintk_add or mprintk_append (I think that I prefer _add).

> output:
> <6>ata1.00: ATA 7, 1024 sectors
> <6> everything seems dandy
>
> Please read the commit messages and comments for more detail. If this
> patchset is accepted, I'll write up Documentation/printk.txt which
> contains describtion of the API and guidelines - "don't pack unrelated
> messages into one" kind of stuff.
>
> This patchset is against the current linux-2.6#master (031f2dcd) and
> contains the following patches.
>
> 0001-printk-keep-log-level-on-multiline-messages.patch
> 0002-printk-implement-v-printk_header.patch
> 0003-printk-implement-merging-printk.patch
> 0004-libata-make-libata-use-printk_header-and-mprintk.patch
>
> drivers/ata/libata-core.c | 202 +++++++++++++++----------
> drivers/ata/libata-eh.c | 150 ++++++++----------
> drivers/ata/libata-pmp.c | 5
> drivers/ata/libata-scsi.c | 6
> drivers/ata/sata_inic162x.c | 2
> drivers/ata/sata_nv.c | 4
> include/linux/kernel.h | 83 ++++++++++
> include/linux/libata.h | 35 ++--
> kernel/printk.c | 354 ++++++++++++++++++++++++++++++++++++++++----
> 9 files changed, 630 insertions(+), 211 deletions(-)
>
> More than half of the code increase in kernel.h are from the dummy
> declarations for !CONFIG_PRINTK. More than one third of printk.c
> increase are comments. On my x86-64 configuration, printk.o grows
> from 30152 to 34128.
>
> libata code grows slightly but the increase is from converting the
> printk wrapper from #define to proper functions. The converted areas
> - device configuration and EH reporting - were reduced in comlexity
> and size. With all-y, drivers/ata/built-in.o shrinks from 726509 to
> 717657 mostly due to the conversion away from macros.


---
~Randy
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