lib/bug.c: use common WARN helper

The traceoff_on_warning option doesn't have any effect on s390, powerpc,
arm64, parisc, and sh because there are two different types of WARN
implementations:

1) The above mentioned architectures treat WARN() as a special case of a
   BUG() exception.  They handle warnings in report_bug() in lib/bug.c.

2) All other architectures just call warn_slowpath_*() directly.  Their
   warnings are handled in warn_slowpath_common() in kernel/panic.c.

Support traceoff_on_warning on all architectures and prevent any future
divergence by using a single common function to emit the warning.

Also remove the '()' from '%pS()', because the parentheses look funky:

  [   45.607629] WARNING: at /root/warn_mod/warn_mod.c:17 .init_dummy+0x20/0x40 [warn_mod]()

Reported-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 24 deletions

diff --git a/lib/bug.c b/lib/bug.c
index 6cde380f09de..bc3656e944d2 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -167,30 +167,8 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
 
         if (warning) {
                 /* this is a WARN_ON rather than BUG/BUG_ON */
-                pr_warn("------------[ cut here ]------------\n");
-
-                if (file)
-                        pr_warn("WARNING: at %s:%u\n", file, line);
-                else
-                        pr_warn("WARNING: at %p [verbose debug info unavailable]\n",
-                                (void *)bugaddr);
-
-                if (panic_on_warn) {
-                        /*
-                         * This thread may hit another WARN() in the panic path.
-                         * Resetting this prevents additional WARN() from
-                         * panicking the system on this thread.  Other threads
-                         * are blocked by the panic_mutex in panic().
-                         */
-                        panic_on_warn = 0;
-                        panic("panic_on_warn set ...\n");
-                }
-
-                print_modules();
-                show_regs(regs);
-                print_oops_end_marker();
-                /* Just a warning, don't kill lockdep. */
-                add_taint(BUG_GET_TAINT(bug), LOCKDEP_STILL_OK);
+                __warn(file, line, (void *)bugaddr, BUG_GET_TAINT(bug), regs,
+                       NULL);
                 return BUG_TRAP_TYPE_WARN;
         }