Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 13 Dec 2016 10:21:27 +0100 | Subject | Re: [PATCH v2 3/4] printk/btrfs: Handle more message headers |
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Hi Petr,
On Wed, Nov 9, 2016 at 1:41 PM, Petr Mladek <pmladek@suse.com> wrote: > The commit 4bcc595ccd80decb4245096e ("printk: reinstate KERN_CONT for > printing continuation lines") allows to define more message headers > for a single message. The motivation is that continuous lines might > get mixed. Therefore it make sense to define the right log level > for every piece of a cont line. > > The current btrfs_printk() macros do not support continuous lines > at the moment. But better be prepared for a custom messages and > avoid potential "lvl" buffer overflow. > > This patch iterates over the entire message header. It is interested > only into the message level like the original code. > > This patch also introduces PRINTK_MAX_SINGLE_HEADER_LEN. Three bytes > are enough for the message level header at the moment. But it used to > be three, see the commit 04d2c8c83d0e3ac5f ("printk: convert the format > for KERN_<LEVEL> to a 2 byte pattern"). > > Also I fixed the default ratelimit level. It looked very strange > when it was different from the default log level. > > Signed-off-by: Petr Mladek <pmladek@suse.com> > --- > fs/btrfs/super.c | 26 +++++++++++++++----------- > include/linux/printk.h | 2 ++ > 2 files changed, 17 insertions(+), 11 deletions(-) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 74ed5aae6cea..c083d84eaa32 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -202,27 +202,31 @@ void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function > void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...) > { > struct super_block *sb = fs_info->sb; > - char lvl[4]; > + char lvl[PRINTK_MAX_SINGLE_HEADER_LEN + 1]; > struct va_format vaf; > va_list args; > - const char *type = logtypes[4]; > + const char *type = NULL; > int kern_level; > struct ratelimit_state *ratelimit;
warning: ‘ratelimit’ may be used uninitialized in this function
So this triggered my attention. It seems my gcc (4.1.2) is not smart enough to notice that ratelimit will be set to a default value if !type.
Still, IMHO the code is too convoluted for the casual reader.
> va_start(args, fmt); > > - kern_level = printk_get_level(fmt); > - if (kern_level) { > + while ((kern_level = printk_get_level(fmt)) != 0) { > size_t size = printk_skip_level(fmt) - fmt; > - memcpy(lvl, fmt, size); > - lvl[size] = '\0'; > + > + if (kern_level >= '0' || kern_level <= '7') { > + memcpy(lvl, fmt, size); > + lvl[size] = '\0'; > + type = logtypes[kern_level - '0']; > + ratelimit = &printk_limits[kern_level - '0']; > + } > fmt += size; > - type = logtypes[kern_level - '0']; > - ratelimit = &printk_limits[kern_level - '0']; > - } else { > + } > + > + if (!type) { > *lvl = '\0'; > - /* Default to debug output */ > - ratelimit = &printk_limits[7]; > + type = logtypes[4]; > + ratelimit = &printk_limits[4]; > } > > vaf.fmt = fmt; > diff --git a/include/linux/printk.h b/include/linux/printk.h > index a0859e169bc3..afe8ccec1672 100644 > --- a/include/linux/printk.h > +++ b/include/linux/printk.h > @@ -10,6 +10,8 @@ > extern const char linux_banner[]; > extern const char linux_proc_banner[]; > > +#define PRINTK_MAX_SINGLE_HEADER_LEN 2
I think you want to use this definition instead of the hardcoded "2" in printk_skip_level():
| static inline const char *printk_skip_level(const char *buffer) | { | if (printk_get_level(buffer)) | return buffer + 2;
return buffer + PRINTK_MAX_SINGLE_HEADER_LEN;
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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