Messages in this thread | | | Date | Fri, 13 Mar 2020 01:00:53 +0000 | From | Luis Chamberlain <> | Subject | Re: [PATCH v2 2/4] fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() |
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On Fri, Mar 13, 2020 at 09:06:46AM +1100, NeilBrown wrote: > On Thu, Mar 12 2020, Eric Biggers wrote: > > > From: Eric Biggers <ebiggers@google.com> > > > > After request_module(), nothing is stopping the module from being > > unloaded until someone takes a reference to it via try_get_module(). > > > > The WARN_ONCE() in get_fs_type() is thus user-reachable, via userspace > > running 'rmmod' concurrently. > > > > Since WARN_ONCE() is for kernel bugs only, not for user-reachable > > situations, downgrade this warning to pr_warn_once(). > > > > Cc: stable@vger.kernel.org > > Cc: Alexei Starovoitov <ast@kernel.org> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: Jeff Vander Stoep <jeffv@google.com> > > Cc: Jessica Yu <jeyu@kernel.org> > > Cc: Kees Cook <keescook@chromium.org> > > Cc: Luis Chamberlain <mcgrof@kernel.org> > > Cc: NeilBrown <neilb@suse.com> > > Signed-off-by: Eric Biggers <ebiggers@google.com> > > --- > > fs/filesystems.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/filesystems.c b/fs/filesystems.c > > index 77bf5f95362da..90b8d879fbaf3 100644 > > --- a/fs/filesystems.c > > +++ b/fs/filesystems.c > > @@ -272,7 +272,9 @@ struct file_system_type *get_fs_type(const char *name) > > fs = __get_fs_type(name, len); > > if (!fs && (request_module("fs-%.*s", len, name) == 0)) { > > fs = __get_fs_type(name, len); > > - WARN_ONCE(!fs, "request_module fs-%.*s succeeded, but still no fs?\n", len, name); > > + if (!fs) > > + pr_warn_once("request_module fs-%.*s succeeded, but still no fs?\n", > > + len, name); > > I strongly support the replacement of "WARN" by "pr_warn". > I wonder if we really want the "once" now. Possibly using rate_limited > would be justified, but I think that in general we should see a warning > every time this event happens.
Since the usefulness of the print is at boot, I think pr_warn_once() is good right now but just because I cannot think of a case where multiple prints are currently desirable, or where this should be possible post-boot. Can you?
Luis [unhandled content-type:application/pgp-signature] | |