linux/drivers/net/netdevsim/bus.c, branch v6.8

netdevsim: Block until all devices are released

2023-10-27T21:48:36Z

Like other buses, devices on the netdevsim bus have a release callback that is invoked when the reference count of the device drops to zero. However, unlike other buses such as PCI, the release callback is not necessarily built into the kernel, as netdevsim can be built as a module. The above is problematic as nothing prevents the module from being unloaded before the release callback has been invoked, which can happen asynchronously. One such example can be found in commit a380687200e0 ("devlink: take device reference for devlink object") where devlink calls put_device() from an RCU callback. The issue is not theoretical and the reproducer in [1] can reliably crash the kernel. The conclusion of this discussion was that the issue should be solved in netdevsim, which is what this patch is trying to do. Add a reference count that is increased when a device is added to the bus and decreased when a device is released. Signal a completion when the reference count drops to zero and wait for the completion when unloading the module so that the module will not be unloaded before all the devices were released. The reference count is initialized to one so that completion is only signaled when unloading the module. With this patch, the reproducer in [1] no longer crashes the kernel. [1] https://lore.kernel.org/netdev/20230619125015.1541143-2-idosch@nvidia.com/ Fixes: a380687200e0 ("devlink: take device reference for devlink object") Signed-off-by: Ido Schimmel Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20231026083343.890689-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski

driver core: bus: mark the struct bus_type for sysfs callbacks as constant

2023-03-23T12:20:40Z

struct bus_type should never be modified in a sysfs callback as there is nothing in the structure to modify, and frankly, the structure is almost never used in a sysfs callback, so mark it as constant to allow struct bus_type to be moved to read-only memory. Cc: "David S. Miller" Cc: "James E.J. Bottomley" Cc: "K. Y. Srinivasan" Cc: Alexander Gordeev Cc: Alexandre Bounine Cc: Alison Schofield Cc: Ben Widawsky Cc: Dexuan Cui Cc: Eric Dumazet Cc: Haiyang Zhang Cc: Hannes Reinecke Cc: Harald Freudenberger Cc: Heiko Carstens Cc: Hu Haowen Cc: Jakub Kicinski Cc: Jens Axboe Cc: Jonathan Corbet Cc: Laurentiu Tudor Cc: Matt Porter Cc: Michael Ellerman Cc: Paolo Abeni Cc: Stuart Yoder Cc: Vasily Gorbik Cc: Vishal Verma Cc: Yanteng Si Acked-by: Ilya Dryomov # rbd Acked-by: Ira Weiny # cxl Reviewed-by: Alex Shi Acked-by: Iwona Winiarska Acked-by: Dan Williams Acked-by: Bjorn Helgaas # pci Acked-by: Wei Liu Acked-by: Martin K. Petersen # scsi Link: https://lore.kernel.org/r/20230313182918.1312597-23-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

netdevsim: fix memory leak in nsim_bus_dev_new()

2022-10-27T17:47:09Z

If device_register() failed in nsim_bus_dev_new(), the value of reference in nsim_bus_dev->dev is 1. obj->name in nsim_bus_dev->dev will not be released. unreferenced object 0xffff88810352c480 (size 16): comm "echo", pid 5691, jiffies 4294945921 (age 133.270s) hex dump (first 16 bytes): 6e 65 74 64 65 76 73 69 6d 31 00 00 00 00 00 00 netdevsim1...... backtrace: [<000000005e2e5e26>] __kmalloc_node_track_caller+0x3a/0xb0 [<0000000094ca4fc8>] kvasprintf+0xc3/0x160 [<00000000aad09bcc>] kvasprintf_const+0x55/0x180 [<000000009bac868d>] kobject_set_name_vargs+0x56/0x150 [<000000007c1a5d70>] dev_set_name+0xbb/0xf0 [<00000000ad0d126b>] device_add+0x1f8/0x1cb0 [<00000000c222ae24>] new_device_store+0x3b6/0x5e0 [<0000000043593421>] bus_attr_store+0x72/0xa0 [<00000000cbb1833a>] sysfs_kf_write+0x106/0x160 [<00000000d0dedb8a>] kernfs_fop_write_iter+0x3a8/0x5a0 [<00000000770b66e2>] vfs_write+0x8f0/0xc80 [<0000000078bb39be>] ksys_write+0x106/0x210 [<00000000005e55a4>] do_syscall_64+0x35/0x80 [<00000000eaa40bbc>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 Fixes: 40e4fe4ce115 ("netdevsim: move device registration and related code to bus.c") Signed-off-by: Zhengchao Shao Link: https://lore.kernel.org/r/20221026015405.128795-1-shaozhengchao@huawei.com Signed-off-by: Jakub Kicinski

netdevsim: convert driver to use unlocked devlink API during init/fini

2022-07-19T03:10:48Z

Prepare for devlink reload being called with devlink->lock held and convert the netdevsim driver to use unlocked devlink API during init and fini flows. Take devl_lock() in reload_down() and reload_up() ops in the meantime before reload cmd is converted to take the lock itself. Signed-off-by: Jiri Pirko Signed-off-by: Jakub Kicinski

netdevsim: rename 'driver' entry points

2021-11-01T13:29:41Z

Rename functions serving as driver entry points from nsim_dev_... to nsim_drv_... this makes the API boundary between bus and dev clearer. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

netdevsim: move max vf config to dev

2021-11-01T13:29:41Z

max_vfs is a strange little beast because the file hangs off of nsim's debugfs, but it configures a field in the bus device. Move it to dev.c, let's look at it as if the device driver was imposing VF limit based on FW info (like pci_sriov_set_totalvfs()). Again, when moving refactor the function not to hold the vfs lock pointlessly while parsing the input. Wrap the access from the read side in READ_ONCE() to appease concurrency checkers. Do not check if return value from snprintf() is negative... Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

netdevsim: move details of vf config to dev

2021-11-01T13:29:41Z

Since "eswitch" configuration was added bus.c contains a lot of device details which really belong to dev.c. Restructure the code while moving it. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

netdevsim: move vfconfig to nsim_dev

2021-11-01T13:29:41Z

When netdevsim got split into the faux bus vfconfig ended up in the bus device (think pci_dev) which is strange because it contains very networky not to say netdevy information. Move it to nsim_dev, which is the driver "priv" structure for the device. To make sure we don't race with probe/remove take the device lock (much like PCI). While at it remove the NULL-checking of vfconfigs. It appears to be pointless. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

netdevsim: take rtnl_lock when assigning num_vfs

2021-11-01T13:29:41Z

Legacy VF NDOs look at num_vfs and then based on that index into vfconfig. If we don't rtnl_lock() num_vfs may get set to 0 and vfconfig freed/replaced while the NDO is running. We don't need to protect replacing vfconfig since it's only done when num_vfs is 0. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

Merge tag 'driver-core-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2021-09-01T15:44:42Z

Pull driver core updates from Greg KH: "Here is the big set of driver core patches for 5.15-rc1. These do change a number of different things across different subsystems, and because of that, there were 2 stable tags created that might have already come into your tree from different pulls that did the following - changed the bus remove callback to return void - sysfs iomem_get_mapping rework Other than those two things, there's only a few small things in here: - kernfs performance improvements for huge numbers of sysfs users at once - tiny api cleanups - other minor changes All of these have been in linux-next for a while with no reported problems, other than the before-mentioned merge issue" * tag 'driver-core-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (33 commits) MAINTAINERS: Add dri-devel for component.[hc] driver core: platform: Remove platform_device_add_properties() ARM: tegra: paz00: Handle device properties with software node API bitmap: extend comment to bitmap_print_bitmask/list_to_buf drivers/base/node.c: use bin_attribute to break the size limitation of cpumap ABI topology: use bin_attribute to break the size limitation of cpumap ABI lib: test_bitmap: add bitmap_print_bitmask/list_to_buf test cases cpumask: introduce cpumap_print_list/bitmask_to_buf to support large bitmask and list sysfs: Rename struct bin_attribute member to f_mapping sysfs: Invoke iomem_get_mapping() from the sysfs open callback debugfs: Return error during {full/open}_proxy_open() on rmmod zorro: Drop useless (and hardly used) .driver member in struct zorro_dev zorro: Simplify remove callback sh: superhyway: Simplify check in remove callback nubus: Simplify check in remove callback nubus: Make struct nubus_driver::remove return void kernfs: dont call d_splice_alias() under kernfs node lock kernfs: use i_lock to protect concurrent inode updates kernfs: switch kernfs to use an rwsem kernfs: use VFS negative dentry caching ...