Re: [cxl:pending 13/21] drivers/cxl/pci.c:511:8-33: WARNING: Threaded IRQ with no primary handler requested without IRQF_ONESHOT (unless it is nested IRQ)

[Ira Weiny <ira.weiny@intel.com>]

Davidlohr Bueso wrote:
> On Sun, 29 Jan 2023, kernel test robot wrote:
> 
> >BCC: lkp@intel.com
> >CC: oe-kbuild-all@lists.linux.dev
> >CC: Alison Schofield <alison.schofield@intel.com>
> >CC: Vishal Verma <vishal.l.verma@intel.com>
> >CC: Ira Weiny <ira.weiny@intel.com>
> >CC: Ben Widawsky <ben.widawsky@intel.com>
> >CC: Dan Williams <dan.j.williams@intel.com>
> >CC: linux-cxl@vger.kernel.org
> >TO: Davidlohr Bueso <dave@stgolabs.net>
> >CC: Dan Williams <dan.j.williams@intel.com>
> >CC: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> >CC: Ira Weiny <ira.weiny@intel.com>
> >
> >tree:   https://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl.git pending
> >head:   ace4b76d4ab70335cffb5a1c8450d3b34c16771a
> >commit: a49aa8141b657a7fd33d86f7bed3ca07567ab37a [13/21] cxl/mem: Wire up event interrupts
> >:::::: branch date: 4 hours ago
> >:::::: commit date: 2 days ago
> >config: microblaze-randconfig-c043-20230129 (https://download.01.org/0day-ci/archive/20230129/202301291620.DxnDWLoW-lkp@intel.com/config)
> >compiler: microblaze-linux-gcc (GCC) 12.1.0
> >
> >If you fix the issue, kindly add following tag where applicable
> >| Reported-by: kernel test robot <lkp@intel.com>
> >| Reported-by: Julia Lawall <julia.lawall@lip6.fr>
> 
> Thanks for reporting, and I'm adding more folks explicitly to the Cc.

Thanks for the Cc.

> 
> >
> >cocci warnings: (new ones prefixed by >>)
> >>> drivers/cxl/pci.c:511:8-33: WARNING: Threaded IRQ with no primary handler requested without IRQF_ONESHOT (unless it is nested IRQ)
> 
> Considering MSIs are edge triggered interrupts, this should be benign.

I'm trying to understand this a bit more.  So I looked in more detail.  I
believe Dan suggested that I could use irq_default_primary_handler() in
this case by passing NULL.  And this would handle threading the irq
processing for me.

It looks from a software standpoint this should work.  But the kdocs
really imply that not masking the irq in the handler may be an issue.
Thus the 'requirement' of using IRQF_ONESHOT.

Is this somehow different with MSI?  Is this a case of the kdocs being a
bit out of date for MSI?

Ira