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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-09-29 07:55:41 -0700 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-12-04 12:27:30 -0800 |
commit | 8ba9153b2c3ab733d64e22adb57820ccb6afc496 (patch) | |
tree | 4cee3952fd004cdfeda6d39d8f7456c3be3aacb2 /kernel/rcu/tree_plugin.h | |
parent | fecbf6f01fbd83e6419ccb7f61d9a6eb987f1d92 (diff) | |
download | linux-stable-8ba9153b2c3ab733d64e22adb57820ccb6afc496.tar.gz linux-stable-8ba9153b2c3ab733d64e22adb57820ccb6afc496.tar.bz2 linux-stable-8ba9153b2c3ab733d64e22adb57820ccb6afc496.zip |
rcu: Remove lock-acquisition loop from rcu_read_unlock_special()
Several releases have come and gone without the warning triggering,
so remove the lock-acquisition loop. Retain the WARN_ON_ONCE()
out of sheer paranoia.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree_plugin.h')
-rw-r--r-- | kernel/rcu/tree_plugin.h | 18 |
1 files changed, 6 insertions, 12 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 57ba873d2f18..ae4ce2b665f8 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -449,19 +449,13 @@ void rcu_read_unlock_special(struct task_struct *t) /* * Remove this task from the list it blocked on. The task - * now remains queued on the rcu_node corresponding to - * the CPU it first blocked on, so the first attempt to - * acquire the task's rcu_node's ->lock will succeed. - * Keep the loop and add a WARN_ON() out of sheer paranoia. + * now remains queued on the rcu_node corresponding to the + * CPU it first blocked on, so there is no longer any need + * to loop. Retain a WARN_ON_ONCE() out of sheer paranoia. */ - for (;;) { - rnp = t->rcu_blocked_node; - raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */ - if (rnp == t->rcu_blocked_node) - break; - WARN_ON_ONCE(1); - raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ - } + rnp = t->rcu_blocked_node; + raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */ + WARN_ON_ONCE(rnp != t->rcu_blocked_node); empty_norm = !rcu_preempt_blocked_readers_cgp(rnp); empty_exp = sync_rcu_preempt_exp_done(rnp); smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */ |