Doug / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit 0632eb3d7563d6a76d49a3860b6352d800c92854

Authored by Paul E. McKenney
Committed by Ingo Molnar
1 parent c26d34a585
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

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>

Showing 3 changed files with 24 additions and 2 deletions Side-by-side Diff

include/linux/lockdep.h
Diff comments   View file @ 0632eb3
... ... @@ -534,5 +534,9 @@
534 534 # define might_lock_read(lock) do { } while (0)
535 535 #endif
536 536  
  537 +#ifdef CONFIG_PROVE_RCU
  538 +extern void lockdep_rcu_dereference(const char *file, const int line);
  539 +#endif
  540 +
537 541 #endif /* __LINUX_LOCKDEP_H */
include/linux/rcupdate.h
Diff comments   View file @ 0632eb3
... ... @@ -182,8 +182,8 @@
182 182 */
183 183 #define rcu_dereference_check(p, c) \
184 184 ({ \
185   - if (debug_locks) \
186   - WARN_ON_ONCE(!(c)); \
  185 + if (debug_locks && !(c)) \
  186 + lockdep_rcu_dereference(__FILE__, __LINE__); \
187 187 rcu_dereference_raw(p); \
188 188 })
189 189  
... ... @@ -3809,4 +3809,22 @@
3809 3809 lockdep_print_held_locks(curr);
3810 3810 }
3811 3811 }
  3812 +
  3813 +void lockdep_rcu_dereference(const char *file, const int line)
  3814 +{
  3815 + struct task_struct *curr = current;
  3816 +
  3817 + if (!debug_locks_off())
  3818 + return;
  3819 + printk("\n==============================================\n");
  3820 + printk( "[ BUG: Unsafe rcu_dereference_check() usage! ]\n");
  3821 + printk( "----------------------------------------------\n");
  3822 + printk("%s:%d invoked rcu_dereference_check() without protection!\n",
  3823 + file, line);
  3824 + printk("\nother info that might help us debug this:\n\n");
  3825 + lockdep_print_held_locks(curr);
  3826 + printk("\nstack backtrace:\n");
  3827 + dump_stack();
  3828 +}
  3829 +EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);