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| author | Zqiang <qiang1.zhang@intel.com> | 2023-01-12 10:48:29 -0800 |
|---|---|---|
| committer | Joel Fernandes (Google) <joel@joelfernandes.org> | 2023-04-05 13:47:44 +0000 |
| commit | 7ea91307ad2dbdd15ed0b762a2d994f816039b9d (patch) | |
| tree | edc0e63de63e5787459307523a809fcce73ec1a0 /kernel/rcu | |
| parent | 46103fe01b02169150f16d8d6e028217c5a7abe5 (diff) | |
| download | linux-7ea91307ad2dbdd15ed0b762a2d994f816039b9d.tar.gz | |
rcu: Permit start_poll_synchronize_rcu_expedited() to be invoked early
According to the commit log of the patch that added it to the kernel,
start_poll_synchronize_rcu_expedited() can be invoked very early, as
in long before rcu_init() has been invoked. But before rcu_init(),
the rcu_data structure's ->mynode field has not yet been initialized.
This means that the start_poll_synchronize_rcu_expedited() function's
attempt to set the CPU's leaf rcu_node structure's ->exp_seq_poll_rq
field will result in a segmentation fault.
This commit therefore causes start_poll_synchronize_rcu_expedited() to
set ->exp_seq_poll_rq only after rcu_init() has initialized all CPUs'
rcu_data structures' ->mynode fields. It also removes the check from
the rcu_init() function so that start_poll_synchronize_rcu_expedited(
is unconditionally invoked. Yes, this might result in an unnecessary
boot-time grace period, but this is down in the noise.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 5 | ||||
| -rw-r--r-- | kernel/rcu/tree_exp.h | 5 |
2 files changed, 5 insertions, 5 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e80e8f128c57f4..90d54571126a26 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4942,9 +4942,8 @@ void __init rcu_init(void) else qovld_calc = qovld; - // Kick-start any polled grace periods that started early. - if (!(per_cpu_ptr(&rcu_data, cpu)->mynode->exp_seq_poll_rq & 0x1)) - (void)start_poll_synchronize_rcu_expedited(); + // Kick-start in case any polled grace periods started early. + (void)start_poll_synchronize_rcu_expedited(); rcu_test_sync_prims(); } diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 7cc4856da0817c..5343f32e7d67e1 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -1066,9 +1066,10 @@ unsigned long start_poll_synchronize_rcu_expedited(void) if (rcu_init_invoked()) raw_spin_lock_irqsave(&rnp->exp_poll_lock, flags); if (!poll_state_synchronize_rcu(s)) { - rnp->exp_seq_poll_rq = s; - if (rcu_init_invoked()) + if (rcu_init_invoked()) { + rnp->exp_seq_poll_rq = s; queue_work(rcu_gp_wq, &rnp->exp_poll_wq); + } } if (rcu_init_invoked()) raw_spin_unlock_irqrestore(&rnp->exp_poll_lock, flags); |