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| author | Paul E. McKenney <paulmck@kernel.org> | 2020-03-18 02:02:06 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-04-27 21:03:52 +0300 |
| commit | 276c410448dbca357a2bc3539acfe04862e5f172 (patch) | |
| tree | 5f25b125fb10b79997286884b3724f5415eb5b11 /include/linux/sched.h | |
| parent | b0afa0f056676ffe0a7213818f09d2460adbcc16 (diff) | |
| download | linux-276c410448dbca357a2bc3539acfe04862e5f172.tar.xz | |
rcu-tasks: Split ->trc_reader_need_end
This commit splits ->trc_reader_need_end by using the rcu_special union.
This change permits readers to check to see if a memory barrier is
required without any added overhead in the common case where no such
barrier is required. This commit also adds the read-side checking.
Later commits will add the machinery to properly set the new
->trc_reader_special.b.need_mb field.
This commit also makes rcu_read_unlock_trace_special() tolerate nested
read-side critical sections within interrupt and NMI handlers.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 864f60e51c41..9437b53cc603 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -613,7 +613,7 @@ union rcu_special { u8 blocked; u8 need_qs; u8 exp_hint; /* Hint for performance. */ - u8 pad; /* No garbage from compiler! */ + u8 need_mb; /* Readers need smp_mb(). */ } b; /* Bits. */ u32 s; /* Set of bits. */ }; @@ -727,7 +727,7 @@ struct task_struct { #ifdef CONFIG_TASKS_TRACE_RCU int trc_reader_nesting; int trc_ipi_to_cpu; - bool trc_reader_need_end; + union rcu_special trc_reader_special; bool trc_reader_checked; struct list_head trc_holdout_list; #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ |