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rcu: Integrate rcu_dereference_check() message into lockdep

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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>
This commit is contained in:
Paul E. McKenney 2010-02-22 17:04:47 -08:00 • committed by Ingo Molnar
parent c26d34a585
commit 0632eb3d75
3 changed files with 24 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

4
include/linux/lockdep.h
View file

@ -534,4 +534,8 @@ do { \
# define might_lock_read(lock) do { } while (0) # define might_lock_read(lock) do { } while (0)
#endif #endif
#ifdef CONFIG_PROVE_RCU
extern void lockdep_rcu_dereference(const char *file, const int line);
#endif
#endif /* __LINUX_LOCKDEP_H */ #endif /* __LINUX_LOCKDEP_H */

4
include/linux/rcupdate.h
View file

@ -182,8 +182,8 @@ static inline int rcu_read_lock_sched_held(void)
*/ */
#define rcu_dereference_check(p, c) \ #define rcu_dereference_check(p, c) \
({ \ ({ \
if (debug_locks) \ if (debug_locks && !(c)) \
WARN_ON_ONCE(!(c)); \ lockdep_rcu_dereference(__FILE__, __LINE__); \
rcu_dereference_raw(p); \ rcu_dereference_raw(p); \
}) })

18
kernel/lockdep.c
View file

@ -3809,3 +3809,21 @@ void lockdep_sys_exit(void)
lockdep_print_held_locks(curr); 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);