Hi, On 2/9/23 20:24, SeongJae Park wrote: > Hi Randy, > > On Thu, 9 Feb 2023 19:26:43 -0800 Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote: > >> Hi, >> >> On 2/9/23 11:20, SeongJae Park wrote: >>> DAMON debugfs interface has announced to be deprecated after >v5.15 LTS >>> kernel is released. And, v6.1.y has announced to be an LTS[1]. >>> >>> Though the announcement was there for a while, some people might not >>> noticed that so far. Also, some users could depend on it and have >>> problems at movng to the alternative (DAMON sysfs interface). >>> >>> For such cases, warn DAMON debugfs interface deprecation with contacts >>> to ask helps when any DAMON debugfs interface file is opened. >>> >>> [1] https://git.kernel.org/pub/scm/docs/kernel/website.git/commit/?id=332e9121320bc7461b2d3a79665caf153e51732c >>> >>> Signed-off-by: SeongJae Park <sj@xxxxxxxxxx> >>> --- >>> mm/damon/dbgfs.c | 16 ++++++++++++++++ >>> 1 file changed, 16 insertions(+) >>> >>> diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c >>> index b3f454a5c682..e551a20b35e3 100644 >>> --- a/mm/damon/dbgfs.c >>> +++ b/mm/damon/dbgfs.c >>> @@ -20,6 +20,11 @@ static int dbgfs_nr_ctxs; >>> static struct dentry **dbgfs_dirs; >>> static DEFINE_MUTEX(damon_dbgfs_lock); >>> >>> +static void damon_dbgfs_warn_deprecation(void) >>> +{ >>> + pr_warn_once("DAMON debugfs interface is deprecated, so users should move to the sysfs interface (DAMON_SYSFS). If you depend on this and cannot move, please report your usecase to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); >>> +} >> >> Line length of 234 is a bit over the limit. >> I think it would be OK to split it at the end of the first sentence, like: >> >> pr_warn_once("DAMON debugfs interface is deprecated, so users should move to the sysfs interface (DAMON_SYSFS).\n"); >> pr_warn_once("If you depend on this and cannot move, please report your usecase to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); >> >> or would that [2 pr_warn_once() calls] not work for some reason? >> >> Or even: >> >> pr_warn_once( >> "DAMON debugfs interface is deprecated, so users should move to the sysfs interface (DAMON_SYSFS).\n"); >> pr_warn_once( >> "If you depend on this and cannot move, please report your usecase to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); >> >> although some people might gag at that one. > > Thank you for your opinion. > > I considered that, but I was worrying if some other messages come between those > two separated messages. I see. > > What do you think about breaking the string like below? I first tried to do so > like memcg hierarchy[1], but ended up to this version because of checkpatch.pl > outputs[2]. However, if others doesn't care, I think this is ok. It's OK to ignore checkpatch sometimes. :) > > pr_warn_once("DAMON debugfs interface is deprecated, " > "so users should move DAMON_SYSFS. If you depend on this " > "and cannot move, please report your usecase to " > "damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx.\n"); > > If breaking user-visible string is not ok, maybe we could make it as short as > your above example. > > pr_warn_once("DAMON_DBGFS is deprecated; please contact to damon@xxxxxxxxxxxxxxx and linux-mm@xxxxxxxxx if you depend on it.\n"); > > May I ask your opinion? I'm OK with either one of these, but I prefer your first example over the second one. > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/memcontrol.c?h=v6.1#n3643 > [2] https://docs.kernel.org/process/coding-style.html#breaking-long-lines-and-strings Thanks. -- ~Randy
