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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-02-22 17:04:47 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-02-25 09:41:01 +0100 |
| commit | 0632eb3d7563d6a76d49a3860b6352d800c92854 (patch) | |
| tree | d998e6d4292a21a91ba1333ffdb1866daf1cfee2 | |
| parent | c26d34a5858f96a564c45048bf5f09319d2abad1 (diff) | |
| download | lwn-0632eb3d7563d6a76d49a3860b6352d800c92854.tar.gz lwn-0632eb3d7563d6a76d49a3860b6352d800c92854.zip | |
rcu: Integrate rcu_dereference_check() message into lockdep
Make rcu_dereference_check() print the list of held locks in
addition to the stack dump to ease debugging.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-3-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | include/linux/lockdep.h | 4 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 4 | ||||
| -rw-r--r-- | kernel/lockdep.c | 18 |
3 files changed, 24 insertions, 2 deletions
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 9ccf0e286b2a..10206a87da19 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -534,4 +534,8 @@ do { \ # define might_lock_read(lock) do { } while (0) #endif +#ifdef CONFIG_PROVE_RCU +extern void lockdep_rcu_dereference(const char *file, const int line); +#endif + #endif /* __LINUX_LOCKDEP_H */ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 839d296a7ac0..1a4de31bd7b4 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -182,8 +182,8 @@ static inline int rcu_read_lock_sched_held(void) */ #define rcu_dereference_check(p, c) \ ({ \ - if (debug_locks) \ - WARN_ON_ONCE(!(c)); \ + if (debug_locks && !(c)) \ + lockdep_rcu_dereference(__FILE__, __LINE__); \ rcu_dereference_raw(p); \ }) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index c62ec14609b9..672c436946ce 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -3809,3 +3809,21 @@ void lockdep_sys_exit(void) lockdep_print_held_locks(curr); } } + +void lockdep_rcu_dereference(const char *file, const int line) +{ + struct task_struct *curr = current; + + if (!debug_locks_off()) + return; + printk("\n==============================================\n"); + printk( "[ BUG: Unsafe rcu_dereference_check() usage! ]\n"); + printk( "----------------------------------------------\n"); + printk("%s:%d invoked rcu_dereference_check() without protection!\n", + file, line); + printk("\nother info that might help us debug this:\n\n"); + lockdep_print_held_locks(curr); + printk("\nstack backtrace:\n"); + dump_stack(); +} +EXPORT_SYMBOL_GPL(lockdep_rcu_dereference); |