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Date:   Tue, 9 Mar 2021 16:00:36 +0100
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        "Ahmed S. Darwish" <a.darwish@linutronix.de>,
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        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        ath9k-devel@qca.qualcomm.com, Kalle Valo <kvalo@codeaurora.org>,
        linux-wireless@vger.kernel.org, Chas Williams <3chas3@gmail.com>,
        linux-atm-general@lists.sourceforge.net,
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        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
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        Stefan Richter <stefanr@s5r6.in-berlin.de>,
        linux1394-devel@lists.sourceforge.net
Subject: Re: [patch 07/14] tasklets: Prevent tasklet_unlock_spin_wait()
 deadlock on RT
Message-ID: <20210309150036.5rcecmmz2wbu4ypc@linutronix.de>
References: <20210309084203.995862150@linutronix.de>
 <20210309084241.988908275@linutronix.de>
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On 2021-03-09 09:42:10 [+0100], Thomas Gleixner wrote:
> tasklet_unlock_spin_wait() spin waits for the TASKLET_STATE_SCHED bit in
> the tasklet state to be cleared. This works on !RT nicely because the
=E2=80=A6

Could you please fold this:

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 07c7329d21aa7..1c14ccd351091 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -663,15 +663,6 @@ static inline int tasklet_trylock(struct tasklet_struc=
t *t)
 void tasklet_unlock(struct tasklet_struct *t);
 void tasklet_unlock_wait(struct tasklet_struct *t);
=20
-/*
- * Do not use in new code. Waiting for tasklets from atomic contexts is
- * error prone and should be avoided.
- */
-static inline void tasklet_unlock_spin_wait(struct tasklet_struct *t)
-{
-	while (test_bit(TASKLET_STATE_RUN, &t->state))
-		cpu_relax();
-}
 #else
 static inline int tasklet_trylock(struct tasklet_struct *t) { return 1; }
 static inline void tasklet_unlock(struct tasklet_struct *t) { }
diff --git a/kernel/softirq.c b/kernel/softirq.c
index f0074f1344402..c9adc5c462485 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -830,8 +830,8 @@ EXPORT_SYMBOL(tasklet_init);
=20
 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
 /*
- * Do not use in new code. There is no real reason to invoke this from
- * atomic contexts.
+ * Do not use in new code. Waiting for tasklets from atomic contexts is
+ * error prone and should be avoided.
  */
 void tasklet_unlock_spin_wait(struct tasklet_struct *t)
 {
--=20
2.30.1