diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2019-12-15 11:38:57 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-02-20 15:58:21 -0800 |
| commit | 82dd8419e225958f01708cda8a3fc6c3c5356228 (patch) | |
| tree | d11b6e4bf1cbcbeaf29bc916762b2fdbaf24c3f1 | |
| parent | 9f01eb5d4936f12d57da84cdfbc2a3623e23a7eb (diff) | |
rcu: Warn on for_each_leaf_node_cpu_mask() from non-leaf
The for_each_leaf_node_cpu_mask() and for_each_leaf_node_possible_cpu()
macros must be invoked only on leaf rcu_node structures. Failing to
abide by this restriction can result in infinite loops on systems with
more than 64 CPUs (or for more than 32 CPUs on 32-bit systems). This
commit therefore adds WARN_ON_ONCE() calls to make misuse of these two
macros easier to debug.
Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| -rw-r--r-- | kernel/rcu/rcu.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 05f936ed167a..f6ce173e35f6 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -325,7 +325,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) * Iterate over all possible CPUs in a leaf RCU node. */ #define for_each_leaf_node_possible_cpu(rnp, cpu) \ - for ((cpu) = cpumask_next((rnp)->grplo - 1, cpu_possible_mask); \ + for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \ + (cpu) = cpumask_next((rnp)->grplo - 1, cpu_possible_mask); \ (cpu) <= rnp->grphi; \ (cpu) = cpumask_next((cpu), cpu_possible_mask)) @@ -335,7 +336,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) #define rcu_find_next_bit(rnp, cpu, mask) \ ((rnp)->grplo + find_next_bit(&(mask), BITS_PER_LONG, (cpu))) #define for_each_leaf_node_cpu_mask(rnp, cpu, mask) \ - for ((cpu) = rcu_find_next_bit((rnp), 0, (mask)); \ + for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \ + (cpu) = rcu_find_next_bit((rnp), 0, (mask)); \ (cpu) <= rnp->grphi; \ (cpu) = rcu_find_next_bit((rnp), (cpu) + 1 - (rnp->grplo), (mask))) |