git: 0e9e3016b9db - stable/12 - LinuxKPI: Add sysctl(8) knob to control verbosity of WARN_ON's.

The branch stable/12 has been updated by hselasky:

URL: https://cgit.FreeBSD.org/src/commit/?id=0e9e3016b9db4572f78ebb7cf475e8fae84e37df

commit 0e9e3016b9db4572f78ebb7cf475e8fae84e37df
Author:     Hans Petter Selasky <hselasky@FreeBSD.org>
AuthorDate: 2021-11-12 14:43:52 +0000
Commit:     Hans Petter Selasky <hselasky@FreeBSD.org>
CommitDate: 2021-11-12 14:43:52 +0000

    LinuxKPI: Add sysctl(8) knob to control verbosity of WARN_ON's.
    
    The purpose of this change is to reduce the amount of dmesg(8) noise when
    VT switching after a panic.
    
    Submitted by:   Greg V <greg@unrelenting.technology>
    Differential Revision:  https://reviews.freebsd.org/D30174
    Sponsored by:   NVIDIA Networking
    
    (cherry picked from commit 2390a1441effaba0e3d0f2f447f448aaf20428f1)
---
 sys/compat/linuxkpi/common/include/linux/kernel.h | 25 +++++++++++++----------
 sys/compat/linuxkpi/common/src/linux_compat.c     |  5 +++++
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/sys/compat/linuxkpi/common/include/linux/kernel.h b/sys/compat/linuxkpi/common/include/linux/kernel.h
index 36d89cf83557..9e96c9935e45 100644
--- a/sys/compat/linuxkpi/common/include/linux/kernel.h
+++ b/sys/compat/linuxkpi/common/include/linux/kernel.h
@@ -105,28 +105,31 @@ extern const volatile int lkpi_build_bug_on_zero;
 	}							\
 } while (0)
 
+extern int linuxkpi_warn_dump_stack;
 #define	WARN_ON(cond) ({					\
-      bool __ret = (cond);					\
-      if (__ret) {						\
+	bool __ret = (cond);					\
+	if (__ret) {						\
 		printf("WARNING %s failed at %s:%d\n",		\
 		    __stringify(cond), __FILE__, __LINE__);	\
-		linux_dump_stack();				\
-      }								\
-      unlikely(__ret);						\
+		if (linuxkpi_warn_dump_stack)				\
+			linux_dump_stack();				\
+	}								\
+	unlikely(__ret);						\
 })
 
 #define	WARN_ON_SMP(cond)	WARN_ON(cond)
 
 #define	WARN_ON_ONCE(cond) ({					\
-      static bool __warn_on_once;				\
-      bool __ret = (cond);					\
-      if (__ret && !__warn_on_once) {				\
+	static bool __warn_on_once;				\
+	bool __ret = (cond);					\
+	if (__ret && !__warn_on_once) {				\
 		__warn_on_once = 1;				\
 		printf("WARNING %s failed at %s:%d\n",		\
 		    __stringify(cond), __FILE__, __LINE__);	\
-		linux_dump_stack();				\
-      }								\
-      unlikely(__ret);						\
+		if (linuxkpi_warn_dump_stack)				\
+			linux_dump_stack();				\
+	}								\
+	unlikely(__ret);						\
 })
 
 #define	oops_in_progress	SCHEDULER_STOPPED()
diff --git a/sys/compat/linuxkpi/common/src/linux_compat.c b/sys/compat/linuxkpi/common/src/linux_compat.c
index bb649e42ab8c..e3ccda6e8f23 100644
--- a/sys/compat/linuxkpi/common/src/linux_compat.c
+++ b/sys/compat/linuxkpi/common/src/linux_compat.c
@@ -98,6 +98,11 @@ int linuxkpi_debug;
 SYSCTL_INT(_compat_linuxkpi, OID_AUTO, debug, CTLFLAG_RWTUN,
     &linuxkpi_debug, 0, "Set to enable pr_debug() prints. Clear to disable.");
 
+int linuxkpi_warn_dump_stack = 0;
+SYSCTL_INT(_compat_linuxkpi, OID_AUTO, warn_dump_stack, CTLFLAG_RWTUN,
+    &linuxkpi_warn_dump_stack, 0,
+    "Set to enable stack traces from WARN_ON(). Clear to disable.");
+
 static struct timeval lkpi_net_lastlog;
 static int lkpi_net_curpps;
 static int lkpi_net_maxpps = 99;