Messages in this thread Patch in this message | | | Date | Wed, 29 Jul 2015 09:17:30 -0400 | From | Peter Hurley <> | Subject | Re: [RFC PATCH v2 0/3] genirq, serial: 8250: Workaround to avoid irq=0 for console |
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On 07/29/2015 07:53 AM, Thomas Gleixner wrote: > On Wed, 29 Jul 2015, Peter Hurley wrote: >> On 07/29/2015 06:32 AM, Thomas Gleixner wrote: >>> On Wed, 29 Jul 2015, Taichi Kageyama wrote: >>>> - Keep interrupt disabled on the CPU which is used to detect >>>> an interrupt during the timeout of autoconfig_irq(). >>>> + Kick printk() on the CPU which detects interrupt >>>> from a console serial port. >>> >>> This is wrong to begin with. How is that supposed to work on an UP >>> machine? Not at all. >>> >>> So no, fix the code which has interrupts disabled accross autoprobing >>> and do not try to apply bandaids somewhere else. >> >> Like printk() from some unrelated driver? > > If that's the cause for the wreckage then yes, we need a way to tell > the printk code not to call into the driver until that initialization > step is done. It's that simple.
Like this?
--- >% -- Subject: [PATCH] genirq: Disable printk() during irq probe
printk() disables interrupts for extended periods of time while outputting to console drivers. This breaks irq probing since the triggered irq may not be serviced (in time) if scheduled on the printk() cpu.
Claim the console_lock() which effectively disables console output.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> --- kernel/irq/autoprobe.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/kernel/irq/autoprobe.c b/kernel/irq/autoprobe.c index 0119b9d..47535d2 100644 --- a/kernel/irq/autoprobe.c +++ b/kernel/irq/autoprobe.c @@ -39,6 +39,13 @@ unsigned long probe_irq_on(void) */ async_synchronize_full(); mutex_lock(&probing_active); + + /* + * printk() breaks irq probing - disable printk output until probe + * completes + */ + console_lock(); + /* * something may have generated an irq long ago and we want to * flush such a longstanding irq before considering it as spurious. @@ -132,6 +139,7 @@ unsigned int probe_irq_mask(unsigned long val) } raw_spin_unlock_irq(&desc->lock); } + console_unlock(); mutex_unlock(&probing_active); return mask & val; @@ -174,6 +182,7 @@ int probe_irq_off(unsigned long val) } raw_spin_unlock_irq(&desc->lock); } + console_unlock(); mutex_unlock(&probing_active); if (nr_of_irqs > 1) -- 2.5.0
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