[PATCH 1/2] lockdep,rtmutex,bug: Show taint flags on error

[Ben Hutchings]

Currently lock debugging is disabled when the kernel is tainted, with
a few exceptions.  It is already recognised that this can be useful
for staging modules (TAINT_CRAP), but that also goes for out-of-tree
modules (TAINT_OOT_MODULE) so long as core kernel developers don't
have to spend time debugging them.  Also, there are several reasons
for tainting that are unlikely to introduce false locking bug reports
(e.g. TAINT_FIRMWARE_WORKAROUND).

Instead of disabling lock debugging, show the taint flags in all
lockdep and rtmutex-debug error messages.

Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 kernel/lockdep.c       |   23 +++++++++++++++--------
 kernel/panic.c         |   10 ----------
 kernel/rtmutex-debug.c |    1 +
 3 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index e69434b..b2c4537 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -567,11 +567,12 @@ static void lockdep_print_held_locks(struct task_struct *curr)
 	}
 }
 
-static void print_kernel_version(void)
+static void print_kernel_ident(void)
 {
-	printk("%s %.*s\n", init_utsname()->release,
+	printk("%s %.*s %s\n", init_utsname()->release,
 		(int)strcspn(init_utsname()->version, " "),
-		init_utsname()->version);
+		init_utsname()->version,
+		print_tainted());
 }
 
 static int very_verbose(struct lock_class *class)
@@ -1148,7 +1149,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth,
 	printk("\n");
 	printk("======================================================\n");
 	printk("[ INFO: possible circular locking dependency detected ]\n");
-	print_kernel_version();
+	print_kernel_ident();
 	printk("-------------------------------------------------------\n");
 	printk("%s/%d is trying to acquire lock:\n",
 		curr->comm, task_pid_nr(curr));
@@ -1487,7 +1488,7 @@ print_bad_irq_dependency(struct task_struct *curr,
 	printk("======================================================\n");
 	printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
 		irqclass, irqclass);
-	print_kernel_version();
+	print_kernel_ident();
 	printk("------------------------------------------------------\n");
 	printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
 		curr->comm, task_pid_nr(curr),
@@ -1716,7 +1717,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
 	printk("\n");
 	printk("=============================================\n");
 	printk("[ INFO: possible recursive locking detected ]\n");
-	print_kernel_version();
+	print_kernel_ident();
 	printk("---------------------------------------------\n");
 	printk("%s/%d is trying to acquire lock:\n",
 		curr->comm, task_pid_nr(curr));
@@ -2223,7 +2224,7 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
 	printk("\n");
 	printk("=================================\n");
 	printk("[ INFO: inconsistent lock state ]\n");
-	print_kernel_version();
+	print_kernel_ident();
 	printk("---------------------------------\n");
 
 	printk("inconsistent {%s} -> {%s} usage.\n",
@@ -2288,7 +2289,7 @@ print_irq_inversion_bug(struct task_struct *curr,
 	printk("\n");
 	printk("=========================================================\n");
 	printk("[ INFO: possible irq lock inversion dependency detected ]\n");
-	print_kernel_version();
+	print_kernel_ident();
 	printk("---------------------------------------------------------\n");
 	printk("%s/%d just changed the state of lock:\n",
 		curr->comm, task_pid_nr(curr));
@@ -3169,6 +3170,7 @@ print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
 	printk("\n");
 	printk("=====================================\n");
 	printk("[ BUG: bad unlock balance detected! ]\n");
+	print_kernel_ident();
 	printk("-------------------------------------\n");
 	printk("%s/%d is trying to release lock (",
 		curr->comm, task_pid_nr(curr));
@@ -3613,6 +3615,7 @@ print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
 	printk("\n");
 	printk("=================================\n");
 	printk("[ BUG: bad contention detected! ]\n");
+	print_kernel_ident();
 	printk("---------------------------------\n");
 	printk("%s/%d is trying to contend lock (",
 		curr->comm, task_pid_nr(curr));
@@ -3987,6 +3990,7 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
 	printk("\n");
 	printk("=========================\n");
 	printk("[ BUG: held lock freed! ]\n");
+	print_kernel_ident();
 	printk("-------------------------\n");
 	printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
 		curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
@@ -4044,6 +4048,7 @@ static void print_held_locks_bug(struct task_struct *curr)
 	printk("\n");
 	printk("=====================================\n");
 	printk("[ BUG: lock held at task exit time! ]\n");
+	print_kernel_ident();
 	printk("-------------------------------------\n");
 	printk("%s/%d is exiting with locks still held!\n",
 		curr->comm, task_pid_nr(curr));
@@ -4141,6 +4146,7 @@ void lockdep_sys_exit(void)
 		printk("\n");
 		printk("================================================\n");
 		printk("[ BUG: lock held when returning to user space! ]\n");
+		print_kernel_ident();
 		printk("------------------------------------------------\n");
 		printk("%s/%d is leaving the kernel with locks still held!\n",
 				curr->comm, curr->pid);
@@ -4160,6 +4166,7 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
 	printk("\n");
 	printk("===============================\n");
 	printk("[ INFO: suspicious RCU usage. ]\n");
+	print_kernel_ident();
 	printk("-------------------------------\n");
 	printk("%s:%d %s!\n", file, line, s);
 	printk("\nother info that might help us debug this:\n\n");
diff --git a/kernel/panic.c b/kernel/panic.c
index b2659360..ad03fb5 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -233,16 +233,6 @@ unsigned long get_taint(void)
 
 void add_taint(unsigned flag)
 {
-	/*
-	 * Can't trust the integrity of the kernel anymore.
-	 * We don't call directly debug_locks_off() because the issue
-	 * is not necessarily serious enough to set oops_in_progress to 1
-	 * Also we want to keep up lockdep for staging development and
-	 * post-warning case.
-	 */
-	if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
-		printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
-
 	set_bit(flag, &tainted_mask);
 }
 EXPORT_SYMBOL(add_taint);
diff --git a/kernel/rtmutex-debug.c b/kernel/rtmutex-debug.c
index a2e7e72..077257f 100644
--- a/kernel/rtmutex-debug.c
+++ b/kernel/rtmutex-debug.c
@@ -101,6 +101,7 @@ void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
 
 	printk("\n============================================\n");
 	printk(  "[ BUG: circular locking deadlock detected! ]\n");
+	printk("%s\n", print_tainted());
 	printk(  "--------------------------------------------\n");
 	printk("%s/%d is deadlocking current task %s/%d\n\n",
 	       task->comm, task_pid_nr(task),
-- 
1.7.7



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