From: Jialin Zhang <zhangjialin11@huawei.com> hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ICJPQ5 -------------------------------- "echo sriov_totalvfs > /sys/bus/pci/devices/$PF_BDF/sriov_numvfs" concurrently may cause the following warnings: Warning 1: sysfs: cannot create duplicate filename '/devices/pci0000:95/0000:95:00.0/pci_bus/0000:97' Call trace: dump_backtrace+0x0/0x200 show_stack+0x20/0x30 dump_stack+0xf0/0x138 sysfs_warn_dup+0x6c/0x90 sysfs_create_dir_ns+0xf8/0x11c create_dir+0x30/0x18c kobject_add_internal+0x5c/0x190 kobject_add+0x98/0x110 device_add+0x100/0x4a0 device_register+0x28/0x40 pci_alloc_child_bus+0x184/0x24c pci_add_new_bus+0x20/0xa4 pci_iov_add_virtfn+0x2a8/0x31c sriov_enable+0x20c/0x4d0 pci_enable_sriov+0x38/0x50 virtio_pci_sriov_configure+0x3c/0xf4 [virtio_pci] sriov_numvfs_store+0xb0/0x1b0 dev_attr_store+0x20/0x34 sysfs_kf_write+0x4c/0x5c kernfs_fop_write_iter+0x130/0x1c0 new_sync_write+0xf0/0x194 vfs_write+0x224/0x2c0 ksys_write+0x74/0x104 __arm64_sys_write+0x24/0x30 el0_svc_common.constprop.0+0x7c/0x1bc do_el0_svc+0x2c/0xa4 el0_svc+0x20/0x30 el0_sync_handler+0xb0/0xb4 el0_sync+0x160/0x180 The reason is that different VFs may create the same pci bus number and try to add new bus concurrently in virtfn_add_bus. Warning 2: proc_dir_entry 'pci/0000:97' already registered Call trace: proc_register+0x100/0x190 proc_mkdir+0x6c/0xa0 pci_proc_attach_device+0xfc/0x120 pci_bus_add_device+0x40/0xd0 pci_iov_add_virtfn+0x2c8/0x31c sriov_enable+0x20c/0x4d0 pci_enable_sriov+0x38/0x50 virtio_pci_sriov_configure+0x3c/0xf4 [virtio_pci] sriov_numvfs_store+0xb0/0x1b0 dev_attr_store+0x20/0x34 sysfs_kf_write+0x4c/0x5c kernfs_fop_write_iter+0x130/0x1c0 new_sync_write+0xf0/0x194 vfs_write+0x224/0x2c0 ksys_write+0x74/0x104 __arm64_sys_write+0x24/0x30 el0_svc_common.constprop.0+0x7c/0x1bc do_el0_svc+0x2c/0xa4 el0_svc+0x20/0x30 el0_sync_handler+0xb0/0xb4 el0_sync+0x160/0x180 The reason is that different VFs may create '/proc/bus/pci/bus_number' directory using the same bus number in pci_proc_attach_device concurrently. Mutex lock can avoid potential conflict. With the patch below the warnings above are no longer appear. Fixes: dd7cc44d0bce ("PCI: add SR-IOV API for Physical Function driver") Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> --- drivers/pci/iov.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 54ec841e3e18..770fadc03f87 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -17,6 +17,8 @@ #define VIRTFN_ID_LEN 17 /* "virtfn%u\0" for 2^32 - 1 */ +static DEFINE_MUTEX(pci_sriov_numvfs_lock); + int pci_iov_virtfn_bus(struct pci_dev *dev, int vf_id) { if (!dev->is_physfn) @@ -435,6 +437,7 @@ static ssize_t sriov_numvfs_store(struct device *dev, if (num_vfs > pci_sriov_get_totalvfs(pdev)) return -ERANGE; + mutex_lock(&pci_sriov_numvfs_lock); device_lock(&pdev->dev); if (num_vfs == pdev->sriov->num_VFs) @@ -478,6 +481,7 @@ static ssize_t sriov_numvfs_store(struct device *dev, exit: device_unlock(&pdev->dev); + mutex_unlock(&pci_sriov_numvfs_lock); if (ret < 0) return ret; -- 2.20.1