Re: NOHZ: local_softirq_pending 08

From: Francois Romieu
Date: Fri Jun 08 2012 - 18:02:35 EST


Thomas Gleixner <tglx@xxxxxxxxxxxxx> :
[...]
> Though the problem is, that it is neither called in interrupt context
> nor with bh disabled, so nothing invokes the softirq before it reaches
> idle.
>
> In hard interrupt context the pending flag is evaluated in irq_exit()
> and the softirqs are invoked from there. If you call that from thread
> context, then a bh_disable/enable pair will make sure that the pending
> softirq is invoked. Did I miss some more ___underscore magic which
> does that ?

No. You _are_ right.

That's why 98ddf986fca17840e46e070354b7e2cd2169da15 triggered the
message: it removed the last bh lock in the r8169 slow work context.

/me slaps head...

The whole thing is probably moot. Dave, can you apply the patch
below on top of a fresh kernel tree ?

diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
index 4a05b68..d452441 100644
--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -5934,11 +5934,7 @@ static void rtl_slow_event_work(struct rtl8169_private *tp)
if (status & LinkChg)
__rtl8169_check_link_status(dev, tp, tp->mmio_addr, true);

- napi_disable(&tp->napi);
- rtl_irq_disable(tp);
-
- napi_enable(&tp->napi);
- napi_schedule(&tp->napi);
+ rtl_irq_enable_all(tp);
}

static void rtl_task(struct work_struct *work)
--
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