Commit-ID: 282b5c2f6f663c008444321fd8fcdd374596046b
Gitweb: http://git.kernel.org/tip/282b5c2f6f663c008444321fd8fcdd374596046b
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Wed, 20 Apr 2011 21:41:59 -0400
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Fri, 22 Apr 2011 11:06:59 +0200
lockdep: Print a nicer description for simple irq lock inversions
Lockdep output can be pretty cryptic, having nicer output
can save a lot of head scratching. When a simple irq inversion
scenario is detected by lockdep (lock A taken in interrupt
context but also in thread context without disabling interrupts)
we now get the following (hopefully more informative) output:
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(lockA);
<Interrupt>
lock(lockA);
*** DEADLOCK ***
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20110421014300.436140880@xxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/lockdep.c | 20 ++++++++++++++++++++
1 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 270cfa4..27c609f 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2158,6 +2158,24 @@ static void check_chain_key(struct task_struct *curr)
#endif
}
+static void
+print_usage_bug_scenario(struct held_lock *lock)
+{
+ struct lock_class *class = hlock_class(lock);
+
+ printk(" Possible unsafe locking scenario:\n\n");
+ printk(" CPU0\n");
+ printk(" ----\n");
+ printk(" lock(");
+ __print_lock_name(class);
+ printk(");\n");
+ printk(" <Interrupt>\n");
+ printk(" lock(");
+ __print_lock_name(class);
+ printk(");\n");
+ printk("\n *** DEADLOCK ***\n\n");
+}
+
static int
print_usage_bug(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
@@ -2186,6 +2204,8 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
print_irqtrace_events(curr);
printk("\nother info that might help us debug this:\n");
+ print_usage_bug_scenario(this);
+
lockdep_print_held_locks(curr);
printk("\nstack backtrace:\n");
--
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