On Mon, May 04, 2020 at 01:15:00PM -0400, Steven Rostedt wrote: > On Sat, 2 May 2020 10:35:53 -0400 > Pavel Tatashin <[email protected]> wrote: > > > kmsg_dump() allows to dump kmesg buffer for various system events: oops, > > panic, reboot, etc. It provides an interface to register a callback call > > for clients, and in that callback interface there is a field "max_reason" > > which gets ignored unless always_kmsg_dump is passed as kernel parameter. > > > > Allow clients to decide max_reason, and keep the current behavior when > > max_reason is not set. > > > > Signed-off-by: Pavel Tatashin <[email protected]> > > --- > > include/linux/kmsg_dump.h | 1 + > > kernel/printk/printk.c | 16 +++++++++------- > > 2 files changed, 10 insertions(+), 7 deletions(-) > > > > diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h > > index 2e7a1e032c71..c0d703b7ce38 100644 > > --- a/include/linux/kmsg_dump.h > > +++ b/include/linux/kmsg_dump.h > > @@ -28,6 +28,7 @@ enum kmsg_dump_reason { > > KMSG_DUMP_RESTART, > > KMSG_DUMP_HALT, > > KMSG_DUMP_POWEROFF, > > + KMSG_DUMP_MAX = KMSG_DUMP_POWEROFF > > Hmm, I didn't realize that enums were allowed to have duplicates. That can > usually screw up logic. I would recommend making that a define afterward. > > #define KMSG_DUMP_MAX KMSG_DUMP_POWEROFF > > As is done in other locations of the kernel.
I've seen it also be the last item in an enum, then comparisons can just do "< KMSG_DUMP_MAX" instead of "<= KMSG_DUMP_MAX". -- Kees Cook
