From: Gautham R Shenoy The dependencies are currently maintained using a structure named locklist. For a dependency A --> B, it saves B's lock_class in an entry that would be linked to A's locks_after list. However, in order to make use of the split chains introduced in the previous patch, we need to enhance this infrastructure to save the read/write states of A and B for each dependency such that we might distinguish between the read and write chains. Signed-off-by: Gautham R Shenoy Signed-off-by: Peter Zijlstra --- include/linux/lockdep.h | 6 ++++++ kernel/lockdep.c | 23 +++++++++++++++++------ 2 files changed, 23 insertions(+), 6 deletions(-) Index: linux-2.6/include/linux/lockdep.h =================================================================== --- linux-2.6.orig/include/linux/lockdep.h +++ linux-2.6/include/linux/lockdep.h @@ -164,6 +164,10 @@ struct lockdep_map { * lock_after/lock_before list of a particular lock. * @dep_class - lock_class of the lock which is involved in a dependency with * the lock to which this entry is linked to. + * @this_lock_rw_state - The read/write state of the lock to which this + * dependency entry belongs to. + * @dep_lock_rw_state - The read/write state of the lock with the lock class + * dep_class in this particular dependecy involvement. * * Every lock has a list of other locks that were taken after it. * We only grow the list, never remove from it: @@ -173,6 +177,8 @@ struct lock_list { struct lock_class *dep_class; struct stack_trace trace; int distance; + unsigned int this_lock_rw_state:3; + unsigned int dep_lock_rw_state:3; /* * The parent field is used to implement breadth-first search, and the Index: linux-2.6/kernel/lockdep.c =================================================================== --- linux-2.6.orig/kernel/lockdep.c +++ linux-2.6/kernel/lockdep.c @@ -816,11 +816,13 @@ static struct lock_list *alloc_list_entr /* * Add a new dependency to the head of the list: */ -static int add_lock_to_list(struct lock_class *class, struct lock_class *this, +static int add_lock_to_list(struct held_lock *this_hlock, + struct held_lock *dep_hlock, struct list_head *head, unsigned long ip, int distance, struct stack_trace *trace) { struct lock_list *entry; + struct lock_class *dep_class = hlock_class(dep_hlock); /* * Lock not present yet - get a new dependency struct and * add it to the list: @@ -829,9 +831,11 @@ static int add_lock_to_list(struct lock_ if (!entry) return 0; - entry->dep_class = this; + entry->dep_class = dep_class; entry->distance = distance; entry->trace = *trace; + entry->this_lock_rw_state = this_hlock->rw_state; + entry->dep_lock_rw_state = dep_hlock->rw_state; /* * Since we never remove from the dependency list, the list can * be walked lockless by other CPUs, it's only allocation @@ -1690,6 +1694,8 @@ check_prev_add(struct task_struct *curr, if (entry->dep_class == hlock_class(next)) { if (distance == 1) entry->distance = 1; + entry->this_lock_rw_state |= prev->rw_state; + entry->dep_lock_rw_state |= next->rw_state; return 2; } } @@ -1697,19 +1703,24 @@ check_prev_add(struct task_struct *curr, if (!trylock_loop && !save_trace(&trace)) return 0; + list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) { + if (entry->dep_class == hlock_class(prev)) { + entry->this_lock_rw_state |= next->rw_state; + entry->dep_lock_rw_state |= prev->rw_state; + } + } + /* * Ok, all validations passed, add the new lock * to the previous lock's dependency list: */ - ret = add_lock_to_list(hlock_class(prev), hlock_class(next), - &hlock_class(prev)->locks_after, + ret = add_lock_to_list(prev, next, &hlock_class(prev)->locks_after, next->acquire_ip, distance, &trace); if (!ret) return 0; - ret = add_lock_to_list(hlock_class(next), hlock_class(prev), - &hlock_class(next)->locks_before, + ret = add_lock_to_list(next, prev, &hlock_class(next)->locks_before, next->acquire_ip, distance, &trace); if (!ret) return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/