Hi Niklas, I love your patch! Perhaps something to improve: [auto build test WARNING on helgaas-pci/next] [also build test WARNING on s390/features tip/x86/core v5.18-rc2 next-20220412] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/intel-lab-lkp/linux/commits/Niklas-Schnelle/PCI-Rework-pci_scan_slot-and-isolated-PCI-functions/20220412-223307 base: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next config: alpha-defconfig (https://download.01.org/0day-ci/archive/20220413/202204130045.AeSigvk8-lkp@xxxxxxxxx/config) compiler: alpha-linux-gcc (GCC) 11.2.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/intel-lab-lkp/linux/commit/5cac6729750b7434ff5d6ae99469e9e54bc9fb6e git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Niklas-Schnelle/PCI-Rework-pci_scan_slot-and-isolated-PCI-functions/20220412-223307 git checkout 5cac6729750b7434ff5d6ae99469e9e54bc9fb6e # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=alpha SHELL=/bin/bash drivers/pci/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): drivers/pci/probe.c: In function 'pci_scan_child_bus_extend': >> drivers/pci/probe.c:2861:13: warning: variable 'nr_devs' set but not used [-Wunused-but-set-variable] 2861 | int nr_devs; | ^~~~~~~ vim +/nr_devs +2861 drivers/pci/probe.c bccf90d6e063d2 Palmer Dabbelt 2017-06-23 2841 1c02ea81006548 Mika Westerberg 2017-10-13 2842 /** 1c02ea81006548 Mika Westerberg 2017-10-13 2843 * pci_scan_child_bus_extend() - Scan devices below a bus 1c02ea81006548 Mika Westerberg 2017-10-13 2844 * @bus: Bus to scan for devices 1c02ea81006548 Mika Westerberg 2017-10-13 2845 * @available_buses: Total number of buses available (%0 does not try to 1c02ea81006548 Mika Westerberg 2017-10-13 2846 * extend beyond the minimal) 1c02ea81006548 Mika Westerberg 2017-10-13 2847 * 1c02ea81006548 Mika Westerberg 2017-10-13 2848 * Scans devices below @bus including subordinate buses. Returns new 1c02ea81006548 Mika Westerberg 2017-10-13 2849 * subordinate number including all the found devices. Passing 1c02ea81006548 Mika Westerberg 2017-10-13 2850 * @available_buses causes the remaining bus space to be distributed 1c02ea81006548 Mika Westerberg 2017-10-13 2851 * equally between hotplug-capable bridges to allow future extension of the 1c02ea81006548 Mika Westerberg 2017-10-13 2852 * hierarchy. 1c02ea81006548 Mika Westerberg 2017-10-13 2853 */ 1c02ea81006548 Mika Westerberg 2017-10-13 2854 static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus, 1c02ea81006548 Mika Westerberg 2017-10-13 2855 unsigned int available_buses) 1c02ea81006548 Mika Westerberg 2017-10-13 2856 { 1c02ea81006548 Mika Westerberg 2017-10-13 2857 unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0; 1c02ea81006548 Mika Westerberg 2017-10-13 2858 unsigned int start = bus->busn_res.start; 5cac6729750b74 Niklas Schnelle 2022-04-12 2859 unsigned int devfn, cmax, max = start; ^1da177e4c3f41 Linus Torvalds 2005-04-16 2860 struct pci_dev *dev; 690f4304104f37 Jan Kiszka 2018-03-07 @2861 int nr_devs; ^1da177e4c3f41 Linus Torvalds 2005-04-16 2862 0207c356ef0e2b Bjorn Helgaas 2009-11-04 2863 dev_dbg(&bus->dev, "scanning bus\n"); ^1da177e4c3f41 Linus Torvalds 2005-04-16 2864 ^1da177e4c3f41 Linus Torvalds 2005-04-16 2865 /* Go find them, Rover! */ 5cac6729750b74 Niklas Schnelle 2022-04-12 2866 for (devfn = 0; devfn < 256; devfn += 8) 690f4304104f37 Jan Kiszka 2018-03-07 2867 nr_devs = pci_scan_slot(bus, devfn); 690f4304104f37 Jan Kiszka 2018-03-07 2868 3e466e2d3a04c7 Bjorn Helgaas 2017-11-30 2869 /* Reserve buses for SR-IOV capability */ 1c02ea81006548 Mika Westerberg 2017-10-13 2870 used_buses = pci_iov_bus_range(bus); 1c02ea81006548 Mika Westerberg 2017-10-13 2871 max += used_buses; a28724b0fb909d Yu Zhao 2009-03-20 2872 ^1da177e4c3f41 Linus Torvalds 2005-04-16 2873 /* ^1da177e4c3f41 Linus Torvalds 2005-04-16 2874 * After performing arch-dependent fixup of the bus, look behind ^1da177e4c3f41 Linus Torvalds 2005-04-16 2875 * all PCI-to-PCI bridges on this bus. ^1da177e4c3f41 Linus Torvalds 2005-04-16 2876 */ 74710ded8e16fc Alex Chiang 2009-03-20 2877 if (!bus->is_added) { 0207c356ef0e2b Bjorn Helgaas 2009-11-04 2878 dev_dbg(&bus->dev, "fixups for bus\n"); ^1da177e4c3f41 Linus Torvalds 2005-04-16 2879 pcibios_fixup_bus(bus); 74710ded8e16fc Alex Chiang 2009-03-20 2880 bus->is_added = 1; 74710ded8e16fc Alex Chiang 2009-03-20 2881 } 74710ded8e16fc Alex Chiang 2009-03-20 2882 1c02ea81006548 Mika Westerberg 2017-10-13 2883 /* 1c02ea81006548 Mika Westerberg 2017-10-13 2884 * Calculate how many hotplug bridges and normal bridges there 1c02ea81006548 Mika Westerberg 2017-10-13 2885 * are on this bus. We will distribute the additional available 1c02ea81006548 Mika Westerberg 2017-10-13 2886 * buses between hotplug bridges. 1c02ea81006548 Mika Westerberg 2017-10-13 2887 */ 1c02ea81006548 Mika Westerberg 2017-10-13 2888 for_each_pci_bridge(dev, bus) { 1c02ea81006548 Mika Westerberg 2017-10-13 2889 if (dev->is_hotplug_bridge) 1c02ea81006548 Mika Westerberg 2017-10-13 2890 hotplug_bridges++; 1c02ea81006548 Mika Westerberg 2017-10-13 2891 else 1c02ea81006548 Mika Westerberg 2017-10-13 2892 normal_bridges++; 1c02ea81006548 Mika Westerberg 2017-10-13 2893 } 1c02ea81006548 Mika Westerberg 2017-10-13 2894 4147c2fd9b12ae Mika Westerberg 2017-10-13 2895 /* 4147c2fd9b12ae Mika Westerberg 2017-10-13 2896 * Scan bridges that are already configured. We don't touch them 4147c2fd9b12ae Mika Westerberg 2017-10-13 2897 * unless they are misconfigured (which will be done in the second 4147c2fd9b12ae Mika Westerberg 2017-10-13 2898 * scan below). 4147c2fd9b12ae Mika Westerberg 2017-10-13 2899 */ 1c02ea81006548 Mika Westerberg 2017-10-13 2900 for_each_pci_bridge(dev, bus) { 1c02ea81006548 Mika Westerberg 2017-10-13 2901 cmax = max; 1c02ea81006548 Mika Westerberg 2017-10-13 2902 max = pci_scan_bridge_extend(bus, dev, max, 0, 0); 3374c545c27c53 Mika Westerberg 2018-05-28 2903 3374c545c27c53 Mika Westerberg 2018-05-28 2904 /* 3374c545c27c53 Mika Westerberg 2018-05-28 2905 * Reserve one bus for each bridge now to avoid extending 3374c545c27c53 Mika Westerberg 2018-05-28 2906 * hotplug bridges too much during the second scan below. 3374c545c27c53 Mika Westerberg 2018-05-28 2907 */ 3374c545c27c53 Mika Westerberg 2018-05-28 2908 used_buses++; 3374c545c27c53 Mika Westerberg 2018-05-28 2909 if (cmax - max > 1) 3374c545c27c53 Mika Westerberg 2018-05-28 2910 used_buses += cmax - max - 1; 1c02ea81006548 Mika Westerberg 2017-10-13 2911 } 4147c2fd9b12ae Mika Westerberg 2017-10-13 2912 4147c2fd9b12ae Mika Westerberg 2017-10-13 2913 /* Scan bridges that need to be reconfigured */ 1c02ea81006548 Mika Westerberg 2017-10-13 2914 for_each_pci_bridge(dev, bus) { 1c02ea81006548 Mika Westerberg 2017-10-13 2915 unsigned int buses = 0; 1c02ea81006548 Mika Westerberg 2017-10-13 2916 1c02ea81006548 Mika Westerberg 2017-10-13 2917 if (!hotplug_bridges && normal_bridges == 1) { 3e466e2d3a04c7 Bjorn Helgaas 2017-11-30 2918 1c02ea81006548 Mika Westerberg 2017-10-13 2919 /* 1c02ea81006548 Mika Westerberg 2017-10-13 2920 * There is only one bridge on the bus (upstream 1c02ea81006548 Mika Westerberg 2017-10-13 2921 * port) so it gets all available buses which it 1c02ea81006548 Mika Westerberg 2017-10-13 2922 * can then distribute to the possible hotplug 1c02ea81006548 Mika Westerberg 2017-10-13 2923 * bridges below. 1c02ea81006548 Mika Westerberg 2017-10-13 2924 */ 1c02ea81006548 Mika Westerberg 2017-10-13 2925 buses = available_buses; 1c02ea81006548 Mika Westerberg 2017-10-13 2926 } else if (dev->is_hotplug_bridge) { 3e466e2d3a04c7 Bjorn Helgaas 2017-11-30 2927 1c02ea81006548 Mika Westerberg 2017-10-13 2928 /* 1c02ea81006548 Mika Westerberg 2017-10-13 2929 * Distribute the extra buses between hotplug 1c02ea81006548 Mika Westerberg 2017-10-13 2930 * bridges if any. 1c02ea81006548 Mika Westerberg 2017-10-13 2931 */ 1c02ea81006548 Mika Westerberg 2017-10-13 2932 buses = available_buses / hotplug_bridges; 3374c545c27c53 Mika Westerberg 2018-05-28 2933 buses = min(buses, available_buses - used_buses + 1); 1c02ea81006548 Mika Westerberg 2017-10-13 2934 } 1c02ea81006548 Mika Westerberg 2017-10-13 2935 1c02ea81006548 Mika Westerberg 2017-10-13 2936 cmax = max; 1c02ea81006548 Mika Westerberg 2017-10-13 2937 max = pci_scan_bridge_extend(bus, dev, cmax, buses, 1); 3374c545c27c53 Mika Westerberg 2018-05-28 2938 /* One bus is already accounted so don't add it again */ 3374c545c27c53 Mika Westerberg 2018-05-28 2939 if (max - cmax > 1) 3374c545c27c53 Mika Westerberg 2018-05-28 2940 used_buses += max - cmax - 1; 1c02ea81006548 Mika Westerberg 2017-10-13 2941 } ^1da177e4c3f41 Linus Torvalds 2005-04-16 2942 e16b46605960bd Keith Busch 2016-07-21 2943 /* e16b46605960bd Keith Busch 2016-07-21 2944 * Make sure a hotplug bridge has at least the minimum requested 1c02ea81006548 Mika Westerberg 2017-10-13 2945 * number of buses but allow it to grow up to the maximum available 1c02ea81006548 Mika Westerberg 2017-10-13 2946 * bus number of there is room. e16b46605960bd Keith Busch 2016-07-21 2947 */ 1c02ea81006548 Mika Westerberg 2017-10-13 2948 if (bus->self && bus->self->is_hotplug_bridge) { 1c02ea81006548 Mika Westerberg 2017-10-13 2949 used_buses = max_t(unsigned int, available_buses, 1c02ea81006548 Mika Westerberg 2017-10-13 2950 pci_hotplug_bus_size - 1); 1c02ea81006548 Mika Westerberg 2017-10-13 2951 if (max - start < used_buses) { 1c02ea81006548 Mika Westerberg 2017-10-13 2952 max = start + used_buses; a20c7f36bd3d20 Mika Westerberg 2017-10-13 2953 a20c7f36bd3d20 Mika Westerberg 2017-10-13 2954 /* Do not allocate more buses than we have room left */ a20c7f36bd3d20 Mika Westerberg 2017-10-13 2955 if (max > bus->busn_res.end) a20c7f36bd3d20 Mika Westerberg 2017-10-13 2956 max = bus->busn_res.end; 1c02ea81006548 Mika Westerberg 2017-10-13 2957 1c02ea81006548 Mika Westerberg 2017-10-13 2958 dev_dbg(&bus->dev, "%pR extended by %#02x\n", 1c02ea81006548 Mika Westerberg 2017-10-13 2959 &bus->busn_res, max - start); 1c02ea81006548 Mika Westerberg 2017-10-13 2960 } e16b46605960bd Keith Busch 2016-07-21 2961 } e16b46605960bd Keith Busch 2016-07-21 2962 ^1da177e4c3f41 Linus Torvalds 2005-04-16 2963 /* ^1da177e4c3f41 Linus Torvalds 2005-04-16 2964 * We've scanned the bus and so we know all about what's on ^1da177e4c3f41 Linus Torvalds 2005-04-16 2965 * the other side of any bridges that may be on this bus plus ^1da177e4c3f41 Linus Torvalds 2005-04-16 2966 * any devices. ^1da177e4c3f41 Linus Torvalds 2005-04-16 2967 * ^1da177e4c3f41 Linus Torvalds 2005-04-16 2968 * Return how far we've got finding sub-buses. ^1da177e4c3f41 Linus Torvalds 2005-04-16 2969 */ 0207c356ef0e2b Bjorn Helgaas 2009-11-04 2970 dev_dbg(&bus->dev, "bus scan returning with max=%02x\n", max); ^1da177e4c3f41 Linus Torvalds 2005-04-16 2971 return max; ^1da177e4c3f41 Linus Torvalds 2005-04-16 2972 } 1c02ea81006548 Mika Westerberg 2017-10-13 2973 -- 0-DAY CI Kernel Test Service https://01.org/lkp
