[PATCH] lib/bug: make panic_on_warn available for all architectures

From: Heiko Carstens
Date: Fri Jan 22 2016 - 08:12:35 EST

Christian Borntraeger reported that panic_on_warn doesn't have any
effect on s390.

The panic_on_warn feature was introduced with 9e3961a09798 ("kernel:
add panic_on_warn"). However it did care only for the case when
WANT_WARN_ON_SLOWPATH is defined. This is turn is only the case for
architectures which do not have an own __WARN_TAINT defined.

Other architectures which do have __WARN_TAINT defined call
report_bug() for warnings within lib/bug.c which does not call panic()
in case panic_on_warn is set.

Let's simply enable the panic_on_warn feature by adding the same code
like it was added to warn_slowpath_common() in panic.c.

This enables panic_on_warn also for arm64, parisc, powerpc, s390 and

Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
lib/bug.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/lib/bug.c b/lib/bug.c
index cff145f032a5..6cde380f09de 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -175,6 +175,17 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
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");
+ }