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| author | Paul E. McKenney <paulmck@kernel.org> | 2023-12-04 20:33:29 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-04-13 14:07:34 +0300 |
| commit | 24e5e1eff8ba236e6c87fd2938a1f79aa1e83f8e (patch) | |
| tree | ca4be1088808356ff25cd0cfb18e26e9d8ccaf90 /include | |
| parent | 4d58c9fb45c70e62c19e8be3f3605889c47601bc (diff) | |
| download | linux-24e5e1eff8ba236e6c87fd2938a1f79aa1e83f8e.tar.xz | |
rcu-tasks: Repair RCU Tasks Trace quiescence check
[ Upstream commit 2eb52fa8900e642b3b5054c4bf9776089d2a935f ]
The context-switch-time check for RCU Tasks Trace quiescence expects
current->trc_reader_special.b.need_qs to be zero, and if so, updates
it to TRC_NEED_QS_CHECKED. This is backwards, because if this value
is zero, there is no RCU Tasks Trace grace period in flight, an thus
no need for a quiescent state. Instead, when a grace period starts,
this field is set to TRC_NEED_QS.
This commit therefore changes the check from zero to TRC_NEED_QS.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/rcupdate.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 9ad656b28847..6466c2f79292 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -189,9 +189,9 @@ void rcu_tasks_trace_qs_blkd(struct task_struct *t); do { \ int ___rttq_nesting = READ_ONCE((t)->trc_reader_nesting); \ \ - if (likely(!READ_ONCE((t)->trc_reader_special.b.need_qs)) && \ + if (unlikely(READ_ONCE((t)->trc_reader_special.b.need_qs) == TRC_NEED_QS) && \ likely(!___rttq_nesting)) { \ - rcu_trc_cmpxchg_need_qs((t), 0, TRC_NEED_QS_CHECKED); \ + rcu_trc_cmpxchg_need_qs((t), TRC_NEED_QS, TRC_NEED_QS_CHECKED); \ } else if (___rttq_nesting && ___rttq_nesting != INT_MIN && \ !READ_ONCE((t)->trc_reader_special.b.blocked)) { \ rcu_tasks_trace_qs_blkd(t); \ |