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| author | Paul E. McKenney <paulmck@kernel.org> | 2020-06-24 02:49:40 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-08-25 03:36:07 +0200 |
| commit | a2b354b9950bb859d8d959f951dda26725b041fb (patch) | |
| tree | a262cadd8ed9ef7492dfd22f02d5bd48db0d7e73 | |
| parent | rcu: Add READ_ONCE() to rcu_do_batch() access to rcu_divisor (diff) | |
| download | linux-a2b354b9950bb859d8d959f951dda26725b041fb.tar.xz linux-a2b354b9950bb859d8d959f951dda26725b041fb.zip | |
rcu: Add READ_ONCE() to rcu_do_batch() access to rcu_resched_ns
Given that sysfs can change the value of rcu_resched_ns at any time,
this commit adds a READ_ONCE() to the sole access to that variable.
While in the area, this commit also adds bounds checking, clamping the
value to at least a millisecond, but no longer than a second.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
| -rw-r--r-- | kernel/rcu/tree.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 1dca14cf66f9..da05afc53493 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2394,8 +2394,12 @@ static void rcu_do_batch(struct rcu_data *rdp) div = READ_ONCE(rcu_divisor); div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div; bl = max(rdp->blimit, pending >> div); - if (unlikely(bl > 100)) - tlimit = local_clock() + rcu_resched_ns; + if (unlikely(bl > 100)) { + long rrn = READ_ONCE(rcu_resched_ns); + + rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn; + tlimit = local_clock() + rrn; + } trace_rcu_batch_start(rcu_state.name, rcu_segcblist_n_cbs(&rdp->cblist), bl); rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl); |