linux-kernel - Re: [PATCH 3/4] x86/ioapic: Fix lost ioapic resource after hot-removal and hotadd

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Date:	Wed, 27 Jul 2016 00:49:46 +0800
From:	kbuild test robot <lkp@...el.com>
To:	Rui Wang <rui.y.wang@...el.com>
Cc:	kbuild-all@...org, helgaas@...nel.org, tglx@...utronix.de,
	rjw@...ysocki.net, tony.luck@...el.com, bhelgaas@...gle.com,
	linux-acpi@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, rui.y.wang@...el.com
Subject: Re: [PATCH 3/4] x86/ioapic: Fix lost ioapic resource after
 hot-removal and hotadd

Hi,

[auto build test WARNING on pm/linux-next]
[also build test WARNING on v4.7 next-20160726]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Rui-Wang/Fixing-a-set-of-bugs-for-ioapic-hotplug/20160727-003628
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: x86_64-randconfig-x015-201630 (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   drivers/acpi/ioapic.c: In function 'handle_ioapic_add':
>> drivers/acpi/ioapic.c:159:18: warning: 'pci_res' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (!res || !res->flags)
                  ~~~^~~~~~~

vim +/pci_res +159 drivers/acpi/ioapic.c

   143			pci_dev_put(dev);
   144			dev = NULL;
   145		}
   146	
   147		crs_res = &ioapic->res;
   148		acpi_walk_resources(handle, METHOD_NAME__CRS, setup_res, crs_res);
   149		if (crs_res->flags == 0) {
   150			acpi_handle_warn(handle, "failed to get resource\n");
   151			goto exit_release;
   152		} else if (request_resource(&iomem_resource, crs_res)) {
   153			acpi_handle_warn(handle, "failed to insert resource\n");
   154			goto exit_release;
   155		}
   156	
   157		/* try pci resource first, then "_CRS" resource */
   158		res = pci_res;
 > 159		if (!res || !res->flags)
   160			res = crs_res;
   161	
   162		if (acpi_register_ioapic(handle, res->start, (u32)gsi_base)) {
   163			acpi_handle_warn(handle, "failed to register IOAPIC\n");
   164			goto exit_release;
   165		}
   166	done:
   167		list_add(&ioapic->list, &ioapic_list);

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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