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>

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index fdf6fa0..f90588a 100644 (file)
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -81,6 +81,12 @@ extern void warn_slowpath_null(const char *file, const int line);
        do { printk(arg); __WARN_TAINT(taint); } while (0)
 #endif
 
+/* used internally by panic.c */
+struct warn_args;
+
+void __warn(const char *file, int line, void *caller, unsigned taint,
+           struct pt_regs *regs, struct warn_args *args);
+
 #ifndef WARN_ON
 #define WARN_ON(condition) ({                                          \
        int __ret_warn_on = !!(condition);                              \

diff --git a/kernel/panic.c b/kernel/panic.c
index d96469d..fa40085 100644 (file)
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -24,6 +24,7 @@
 #include <linux/init.h>
 #include <linux/nmi.h>
 #include <linux/console.h>
+#include <linux/bug.h>
 
 #define PANIC_TIMER_STEP 100
 #define PANIC_BLINK_SPD 18
@@ -449,20 +450,25 @@ void oops_exit(void)
        kmsg_dump(KMSG_DUMP_OOPS);
 }
 
-#ifdef WANT_WARN_ON_SLOWPATH
-struct slowpath_args {
+struct warn_args {
        const char *fmt;
        va_list args;
 };
 
-static void warn_slowpath_common(const char *file, int line, void *caller,
-                                unsigned taint, struct slowpath_args *args)
+void __warn(const char *file, int line, void *caller, unsigned taint,
+           struct pt_regs *regs, struct warn_args *args)
 {
        disable_trace_on_warning();
 
        pr_warn("------------[ cut here ]------------\n");
-       pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
-               raw_smp_processor_id(), current->pid, file, line, caller);
+
+       if (file)
+               pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
+                       raw_smp_processor_id(), current->pid, file, line,
+                       caller);
+       else
+               pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
+                       raw_smp_processor_id(), current->pid, caller);
 
        if (args)
                vprintk(args->fmt, args->args);
@@ -479,20 +485,27 @@ static void warn_slowpath_common(const char *file, int line, void *caller,
        }
 
        print_modules();
-       dump_stack();
+
+       if (regs)
+               show_regs(regs);
+       else
+               dump_stack();
+
        print_oops_end_marker();
+
        /* Just a warning, don't kill lockdep. */
        add_taint(taint, LOCKDEP_STILL_OK);
 }
 
+#ifdef WANT_WARN_ON_SLOWPATH
 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 {
-       struct slowpath_args args;
+       struct warn_args args;
 
        args.fmt = fmt;
        va_start(args.args, fmt);
-       warn_slowpath_common(file, line, __builtin_return_address(0),
-                            TAINT_WARN, &args);
+       __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
+              &args);
        va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt);
@@ -500,20 +513,18 @@ EXPORT_SYMBOL(warn_slowpath_fmt);
 void warn_slowpath_fmt_taint(const char *file, int line,
                             unsigned taint, const char *fmt, ...)
 {
-       struct slowpath_args args;
+       struct warn_args args;
 
        args.fmt = fmt;
        va_start(args.args, fmt);
-       warn_slowpath_common(file, line, __builtin_return_address(0),
-                            taint, &args);
+       __warn(file, line, __builtin_return_address(0), taint, NULL, &args);
        va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
 
 void warn_slowpath_null(const char *file, int line)
 {
-       warn_slowpath_common(file, line, __builtin_return_address(0),
-                            TAINT_WARN, NULL);
+       __warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
 }
 EXPORT_SYMBOL(warn_slowpath_null);
 #endif

diff --git a/lib/bug.c b/lib/bug.c
index 6cde380..bc3656e 100644 (file)
--- 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;
        }