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| author |   Paul E. McKenney <paulmck@linux.ibm.com> | 2019-02-12 10:44:33 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-03-26 14:39:24 -0700 |
| commit | 5cdfd174ea6c2dc1d331b61bdc9572698658600a (patch) | |
| tree | e038dc46ffae28bfda548887b93056e6a5741afb /kernel/rcu | |
| parent | Linux 5.1-rc1 (diff) | |
| download | linux-dev-5cdfd174ea6c2dc1d331b61bdc9572698658600a.tar.xz linux-dev-5cdfd174ea6c2dc1d331b61bdc9572698658600a.zip | |
srcu: Check for in-flight callbacks in _cleanup_srcu_struct()
If someone fails to drain the corresponding SRCU callbacks (for
example, by failing to invoke srcu_barrier()) before invoking either
cleanup_srcu_struct() or cleanup_srcu_struct_quiesced(), the resulting
diagnostic is an ambiguous use-after-free diagnostic, and even then
only if you are running something like KASAN. This commit therefore
improves SRCU diagnostics by adding checks for in-flight callbacks at
_cleanup_srcu_struct() time.
Note that these diagnostics can still be defeated, for example, by
invoking call_srcu() concurrently with cleanup_srcu_struct(). Which is
a really bad idea, but sometimes all too easy to do. But even then,
these diagnostics have at least some probability of catching the problem.
Reported-by: Sagi Grimberg <sagi@grimberg.me>
Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/srcutree.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index a60b8ba9e1ac..4f30f3ecabc1 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -387,6 +387,8 @@ void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced) del_timer_sync(&sdp->delay_work); flush_work(&sdp->work); } + if (WARN_ON(rcu_segcblist_n_cbs(&sdp->srcu_cblist))) + return; /* Forgot srcu_barrier(), so just leak it! */ } if (WARN_ON(rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) != SRCU_STATE_IDLE) || WARN_ON(srcu_readers_active(ssp))) { |