Re: [PATCH v2 3/4] printk/btrfs: Handle more message headers

[Petr Mladek]

On Fri 2016-11-11 12:41:34, Steven Rostedt wrote:
> On Wed,  9 Nov 2016 13:41:30 +0100
> Petr Mladek <pmladek@xxxxxxxx> 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@xxxxxxxx>
> > ---
> >  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;
> >  
> >  	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') {
> 
> Shouldn't this be kernel_level >= '0' && kern_level <= '7' ?

Great catch! I am idiot.

I did all these patches in a hurry before the Plumber conference.
I was blind when checking it later :-(

Thanks a lot for such a careful review.

Best Regards,
Petr