Commit-ID: 48702ecf308e53f176c1f6fdc193d622ded54ac0 Gitweb: http://git.kernel.org/tip/48702ecf308e53f176c1f6fdc193d622ded54ac0 Author: Steven Rostedt <srostedt@xxxxxxxxxx> AuthorDate: Wed, 20 Apr 2011 21:41:56 -0400 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Fri, 22 Apr 2011 11:06:58 +0200 lockdep: Print a nicer description for simple deadlocks Lockdep output can be pretty cryptic, having nicer output can save a lot of head scratching. When a simple deadlock scenario is detected by lockdep (lock A -> lock A) we now get the following new output: other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(lock)->rlock); lock(&(lock)->rlock); *** 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/20110421014259.643930104@xxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/lockdep.c | 21 +++++++++++++++++++++ 1 files changed, 21 insertions(+), 0 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 73cebd7..c4cc5d1 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -1664,6 +1664,26 @@ static inline void inc_chains(void) #endif +static void +print_deadlock_scenario(struct held_lock *nxt, + struct held_lock *prv) +{ + struct lock_class *next = hlock_class(nxt); + struct lock_class *prev = hlock_class(prv); + + printk(" Possible unsafe locking scenario:\n\n"); + printk(" CPU0\n"); + printk(" ----\n"); + printk(" lock("); + __print_lock_name(prev); + printk(");\n"); + printk(" lock("); + __print_lock_name(next); + printk(");\n"); + printk("\n *** DEADLOCK ***\n\n"); + printk(" May be due to missing lock nesting notation\n\n"); +} + static int print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, struct held_lock *next) @@ -1682,6 +1702,7 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, print_lock(prev); printk("\nother info that might help us debug this:\n"); + print_deadlock_scenario(next, prev); lockdep_print_held_locks(curr); printk("\nstack backtrace:\n"); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html