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rcu-tasks: Make trc_read_check_handler() fetch ->trc_reader_nesting only once
This commit replaces the pair of READ_ONCE(t->trc_reader_nesting) calls with a single such call and a local variable. This makes the code's intent more clear. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <kafai@fb.com> Cc: KP Singh <kpsingh@kernel.org>
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parent
550611269b
commit
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1 changed files with 4 additions and 2 deletions
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@ -1278,6 +1278,7 @@ static void trc_del_holdout(struct task_struct *t)
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/* IPI handler to check task state. */
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/* IPI handler to check task state. */
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static void trc_read_check_handler(void *t_in)
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static void trc_read_check_handler(void *t_in)
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{
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{
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int nesting;
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struct task_struct *t = current;
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struct task_struct *t = current;
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struct task_struct *texp = t_in;
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struct task_struct *texp = t_in;
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@ -1287,12 +1288,13 @@ static void trc_read_check_handler(void *t_in)
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// If the task is not in a read-side critical section, and
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// If the task is not in a read-side critical section, and
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// if this is the last reader, awaken the grace-period kthread.
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// if this is the last reader, awaken the grace-period kthread.
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if (likely(!READ_ONCE(t->trc_reader_nesting))) {
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nesting = READ_ONCE(t->trc_reader_nesting);
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if (likely(!nesting)) {
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rcu_trc_cmpxchg_need_qs(t, 0, TRC_NEED_QS_CHECKED);
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rcu_trc_cmpxchg_need_qs(t, 0, TRC_NEED_QS_CHECKED);
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goto reset_ipi;
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goto reset_ipi;
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}
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}
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// If we are racing with an rcu_read_unlock_trace(), try again later.
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// If we are racing with an rcu_read_unlock_trace(), try again later.
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if (unlikely(READ_ONCE(t->trc_reader_nesting) < 0))
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if (unlikely(nesting < 0))
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goto reset_ipi;
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goto reset_ipi;
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// Get here if the task is in a read-side critical section. Set
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// Get here if the task is in a read-side critical section. Set
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