Messages in this thread | | | Subject | Re: [PATCH] printk: Add loglevel for "do not print to consoles". | From | Tetsuo Handa <> | Date | Thu, 7 May 2020 14:13:34 +0900 |
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On 2020/05/07 10:02, Joe Perches wrote: >>> printk_get_level / printk_skip_level and the various >>> uses of %pV using printk_get_level >>> >> >> Excuse me, but what do you mean? >> >> I wish printk() accepts "loglevel" argument detached from "fmt" argument (e.g. > > I think that's a bad idea as it would expand > _every_ use of printk with another argument > and overall code size would increase for very > little value.
I'm not saying that we should add loglevel argument to all printk() callers. I'm saying that we could add a variant of printk() which accepts loglevel argument (say, e.g. printkl() and vprintkl()).
I think that some of printk_get_level() users are using printk_get_level() only for detaching loglevel argument from fmt argument.
For example, fs/f2fs/f2fs.h defines f2fs_{err,warn,notice,info,debug}() which pass KERN_* to f2fs_printk(), but f2fs_printk() in fs/f2fs/super.c trims KERN_* and passes it back to printk(). If printkl() were there, f2fs_err() etc. can directly call printkl() (and avoids printk_get_level(), printk_skip_level() and "struct va_format").
fs/btrfs/ctree.h similarly defines btrfs_{emerg,alert,crit,err,warn,notice,info}() and their RCU and latelimited variants which pass KERN_* to btrfs_printk(), but btrfs_printk() in fs/btrfs/super.c trims KERN_* and passes it back to printk(). If printkl() were there, btrfs_emerg() etc. can avoid printk_get_level() and printk_skip_level().
sound/core/misc.c defines __snd_printk() which allows inserting filename and line number. If printkl() were there, __snd_printk() can avoid printk_get_level() and printk_skip_level(), and can constify format argument variable (which is currently writable just in order to embed loglevel argument).
I don't know how the lockless logbuf will replace printk_safe_flush_buffer(). But I guess it is possible to avoid printk_safe_flush_buffer() and printk_skip_level() as demonstrated by https://lkml.kernel.org/r/5e192ca2-3b24-0b45-fc13-51feec43c216@i-love.sakura.ne.jp .
Then, printk_skip_headers() will be the only user of printk_skip_level(). I don't know how vkdb_printf() works, but vkdb_printf() is currently using printk_skip_level() in order to remove loglevel argument. We can avoid printk_skip_level() if loglevel argument is detached from fmt argument.
> > And do look at the code and uses of printk_get_level.
And again, what am I missing?
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