From 96cad4ca4c1f78fd57a8e3ae1193457606be9eb4 Mon Sep 17 00:00:00 2001
From: Rob Norris <robn@despairlabs.com>
Date: Sun, 21 Apr 2024 21:43:53 +1000
Subject: [PATCH] libspl/assert: show process/task details in assert output

Makes it much easier to see what thing complained.

Getting thread id, program name and thread name vary wildly between
Linux and FreeBSD, so those are set up in macros. pthread_getname_np()
did not appear in musl until very recently, but the same info has always
been available via prctl(PR_GET_NAME), so we use that instead.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #16140
---
 config/user.m4      |  2 +-
 lib/libspl/assert.c | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/config/user.m4 b/config/user.m4
index 87df8c7cca..3a69086a9d 100644
--- a/config/user.m4
+++ b/config/user.m4
@@ -31,7 +31,7 @@ AC_DEFUN([ZFS_AC_CONFIG_USER], [
 	ZFS_AC_CONFIG_USER_MAKEDEV_IN_MKDEV
 	ZFS_AC_CONFIG_USER_ZFSEXEC
 
-	AC_CHECK_FUNCS([execvpe issetugid mlockall strlcat strlcpy])
+	AC_CHECK_FUNCS([execvpe issetugid mlockall strlcat strlcpy gettid])
 
 	AC_SUBST(RM)
 ])
diff --git a/lib/libspl/assert.c b/lib/libspl/assert.c
index 9d44740d4e..185ec65cb8 100644
--- a/lib/libspl/assert.c
+++ b/lib/libspl/assert.c
@@ -22,9 +22,32 @@
  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+/*
+ * Copyright (c) 2024, Rob Norris <robn@despairlabs.com>
+ */
 
 #include <assert.h>
 
+#if defined(__linux__)
+#include <errno.h>
+#include <sys/prctl.h>
+#ifdef HAVE_GETTID
+#define	libspl_gettid()		gettid()
+#else
+#include <sys/syscall.h>
+#define	libspl_gettid()		((pid_t)syscall(__NR_gettid))
+#endif
+#define	libspl_getprogname()	(program_invocation_short_name)
+#define	libspl_getthreadname(buf, len)	\
+	prctl(PR_GET_NAME, (unsigned long)(buf), 0, 0, 0)
+#elif defined(__FreeBSD__)
+#include <pthread_np.h>
+#define	libspl_gettid()		pthread_getthreadid_np()
+#define	libspl_getprogname()	getprogname()
+#define	libspl_getthreadname(buf, len)	\
+	pthread_getname_np(pthread_self(), buf, len);
+#endif
+
 static boolean_t libspl_assert_ok = B_FALSE;
 
 void
@@ -39,13 +62,22 @@ libspl_assertf(const char *file, const char *func, int line,
     const char *format, ...)
 {
 	va_list args;
+	char tname[64];
+
+	libspl_getthreadname(tname, sizeof (tname));
+
+	fprintf(stderr, "ASSERT at %s:%d:%s()\n", file, line, func);
 
 	va_start(args, format);
 	vfprintf(stderr, format, args);
-	fprintf(stderr, "\n");
-	fprintf(stderr, "ASSERT at %s:%d:%s()", file, line, func);
 	va_end(args);
 
+	fprintf(stderr, "\n"
+	    "  PID: %-8u  COMM: %s\n"
+	    "  TID: %-8u  NAME: %s\n",
+	    getpid(), libspl_getprogname(),
+	    libspl_gettid(), tname);
+
 #if !__has_feature(attribute_analyzer_noreturn) && !defined(__COVERITY__)
 	if (libspl_assert_ok) {
 		return;