54 lines
1.6 KiB
Diff
54 lines
1.6 KiB
Diff
From: Ingo Molnar <mingo@elte.hu>
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Date: Fri, 3 Jul 2009 08:44:07 -0500
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Subject: relay: Fix timer madness
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.8/older/patches-4.8.6-rt5.tar.xz
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remove timer calls (!!!) from deep within the tracing infrastructure.
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This was totally bogus code that can cause lockups and worse. Poll
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the buffer every 2 jiffies for now.
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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kernel/relay.c | 14 +++++---------
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1 file changed, 5 insertions(+), 9 deletions(-)
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--- a/kernel/relay.c
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+++ b/kernel/relay.c
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@@ -336,6 +336,10 @@ static void wakeup_readers(unsigned long
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{
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struct rchan_buf *buf = (struct rchan_buf *)data;
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wake_up_interruptible(&buf->read_wait);
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+ /*
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+ * Stupid polling for now:
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+ */
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+ mod_timer(&buf->timer, jiffies + 1);
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}
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/**
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@@ -353,6 +357,7 @@ static void __relay_reset(struct rchan_b
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init_waitqueue_head(&buf->read_wait);
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kref_init(&buf->kref);
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setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf);
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+ mod_timer(&buf->timer, jiffies + 1);
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} else
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del_timer_sync(&buf->timer);
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@@ -767,15 +772,6 @@ size_t relay_switch_subbuf(struct rchan_
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else
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buf->early_bytes += buf->chan->subbuf_size -
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buf->padding[old_subbuf];
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- smp_mb();
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- if (waitqueue_active(&buf->read_wait))
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- /*
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- * Calling wake_up_interruptible() from here
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- * will deadlock if we happen to be logging
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- * from the scheduler (trying to re-grab
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- * rq->lock), so defer it.
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- */
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- mod_timer(&buf->timer, jiffies + 1);
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}
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old = buf->data;
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