GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-19 21:21:09 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

rcu: Use READ_ONCE() for ->expmask in rcu_read_unlock_special()

Browse source 
The rcu_node structure's ->expmask field is updated only when holding the
->lock, but is also accessed locklessly.  This means that all ->expmask
updates must use WRITE_ONCE() and all reads carried out without holding
->lock must use READ_ONCE().  This commit therefore changes the lockless
->expmask read in rcu_read_unlock_special() to use READ_ONCE().

Reported-by: syzbot+99f4ddade3c22ab0cf23@syzkaller.appspotmail.com
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Marco Elver <elver@google.com>
This commit is contained in:
Paul E. McKenney 2019-11-04 08:22:45 -08:00
parent 3717e1e9f2
commit c51f83c315
1 changed files with 1 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

2
kernel/rcu/tree_plugin.h
View file

@ -599,7 +599,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
struct rcu_node *rnp = rdp->mynode; struct rcu_node *rnp = rdp->mynode;
exp = (t->rcu_blocked_node && t->rcu_blocked_node->exp_tasks) || exp = (t->rcu_blocked_node && t->rcu_blocked_node->exp_tasks) ||
(rdp->grpmask & rnp->expmask) || (rdp->grpmask & READ_ONCE(rnp->expmask)) ||
tick_nohz_full_cpu(rdp->cpu); tick_nohz_full_cpu(rdp->cpu);
// Need to defer quiescent state until everything is enabled. // Need to defer quiescent state until everything is enabled.
if (irqs_were_disabled && use_softirq && if (irqs_were_disabled && use_softirq &&