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| author | Paul E. McKenney <paulmck@kernel.org> | 2022-10-14 19:39:43 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-01-25 15:27:26 -0800 |
| commit | 10108826191ab30388e8ae9d54505a628f78a7ec (patch) | |
| tree | 7c157b43198990c961bcd519dbea1ac64f0454c1 | |
| parent | db44bac18a1330d3bbed5f07a8ff3d2892656678 (diff) | |
| download | linux-10108826191ab30388e8ae9d54505a628f78a7ec.tar.gz linux-10108826191ab30388e8ae9d54505a628f78a7ec.tar.bz2 linux-10108826191ab30388e8ae9d54505a628f78a7ec.zip | |
rcu-tasks: Provide rcu_trace_implies_rcu_gp()
[ Upstream commit e6c86c513f440bec5f1046539c7e3c6c653842da ]
As an accident of implementation, an RCU Tasks Trace grace period also
acts as an RCU grace period. However, this could change at any time.
This commit therefore creates an rcu_trace_implies_rcu_gp() that currently
returns true to codify this accident. Code relying on this accident
must call this function to verify that this accident is still happening.
Reported-by: Hou Tao <houtao@huaweicloud.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Link: https://lore.kernel.org/r/20221014113946.965131-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 876673364161 ("bpf: Defer the free of inner map when necessary")
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | include/linux/rcupdate.h | 12 | ||||
| -rw-r--r-- | kernel/rcu/tasks.h | 2 |
2 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index e9e61cd27ef6..46bd9a331fd5 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -243,6 +243,18 @@ static inline void exit_tasks_rcu_finish(void) { } #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */ /** + * rcu_trace_implies_rcu_gp - does an RCU Tasks Trace grace period imply an RCU grace period? + * + * As an accident of implementation, an RCU Tasks Trace grace period also + * acts as an RCU grace period. However, this could change at any time. + * Code relying on this accident must call this function to verify that + * this accident is still happening. + * + * You have been warned! + */ +static inline bool rcu_trace_implies_rcu_gp(void) { return true; } + +/** * cond_resched_tasks_rcu_qs - Report potential quiescent states to RCU * * This macro resembles cond_resched(), except that it is defined to diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index c1f18c63b9b1..b5d5b6cf093a 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1570,6 +1570,8 @@ static void rcu_tasks_trace_postscan(struct list_head *hop) { // Wait for late-stage exiting tasks to finish exiting. // These might have passed the call to exit_tasks_rcu_finish(). + + // If you remove the following line, update rcu_trace_implies_rcu_gp()!!! synchronize_rcu(); // Any tasks that exit after this point will set // TRC_NEED_QS_CHECKED in ->trc_reader_special.b.need_qs. |