linux/drivers/base/dd.c, branch v6.0

driver core: Don't probe devices after bus_type.match() probe deferral

2022-09-01T13:57:13Z

Both __device_attach_driver() and __driver_attach() check the return code of the bus_type.match() function to see if the device needs to be added to the deferred probe list. After adding the device to the list, the logic attempts to bind the device to the driver anyway, as if the device had matched with the driver, which is not correct. If __device_attach_driver() detects that the device in question is not ready to match with a driver on the bus, then it doesn't make sense for the device to attempt to bind with the current driver or continue attempting to match with any of the other drivers on the bus. So, update the logic in __device_attach_driver() to reflect this. If __driver_attach() detects that a driver tried to match with a device that is not ready to match yet, then the driver should not attempt to bind with the device. However, the driver can still attempt to match and bind with other devices on the bus, as drivers can be bound to multiple devices. So, update the logic in __driver_attach() to reflect this. Fixes: 656b8035b0ee ("ARM: 8524/1: driver cohandle -EPROBE_DEFER from bus_type.match()") Cc: stable@vger.kernel.org Cc: Saravana Kannan Reported-by: Guenter Roeck Tested-by: Guenter Roeck Tested-by: Linus Walleij Reviewed-by: Saravana Kannan Signed-off-by: Isaac J. Manjarres Link: https://lore.kernel.org/r/20220817184026.3468620-1-isaacmanjarres@google.com Signed-off-by: Greg Kroah-Hartman

Revert "driver core: Delete driver_deferred_probe_check_state()"

2022-08-23T11:14:02Z

This reverts commit 9cbffc7a59561be950ecc675d19a3d2b45202b2b. There are a few more issues to fix that have been reported in the thread for the original series [1]. We'll need to fix those before this will work. So, revert it for now. [1] - https://lore.kernel.org/lkml/20220601070707.3946847-1-saravanak@google.com/ Fixes: 9cbffc7a5956 ("driver core: Delete driver_deferred_probe_check_state()") Tested-by: Tony Lindgren Tested-by: Peng Fan Tested-by: Douglas Anderson Tested-by: Alexander Stein Reviewed-by: Tony Lindgren Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20220819221616.2107893-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: fix potential deadlock in __driver_attach

2022-06-27T14:43:51Z

In __driver_attach function, There are also AA deadlock problem, like the commit b232b02bf3c2 ("driver core: fix deadlock in __device_attach"). stack like commit b232b02bf3c2 ("driver core: fix deadlock in __device_attach"). list below: In __driver_attach function, The lock holding logic is as follows: ... __driver_attach if (driver_allows_async_probing(drv)) device_lock(dev) // get lock dev async_schedule_dev(__driver_attach_async_helper, dev); // func async_schedule_node async_schedule_node_domain(func) entry = kzalloc(sizeof(struct async_entry), GFP_ATOMIC); /* when fail or work limit, sync to execute func, but __driver_attach_async_helper will get lock dev as will, which will lead to A-A deadlock. */ if (!entry || atomic_read(&entry_count) > MAX_WORK) { func; else queue_work_node(node, system_unbound_wq, &entry->work) device_unlock(dev) As above show, when it is allowed to do async probes, because of out of memory or work limit, async work is not be allowed, to do sync execute instead. it will lead to A-A deadlock because of __driver_attach_async_helper getting lock dev. Reproduce: and it can be reproduce by make the condition (if (!entry || atomic_read(&entry_count) > MAX_WORK)) untenable, like below: [ 370.785650] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 370.787154] task:swapper/0 state:D stack: 0 pid: 1 ppid: 0 flags:0x00004000 [ 370.788865] Call Trace: [ 370.789374] [ 370.789841] __schedule+0x482/0x1050 [ 370.790613] schedule+0x92/0x1a0 [ 370.791290] schedule_preempt_disabled+0x2c/0x50 [ 370.792256] __mutex_lock.isra.0+0x757/0xec0 [ 370.793158] __mutex_lock_slowpath+0x1f/0x30 [ 370.794079] mutex_lock+0x50/0x60 [ 370.794795] __device_driver_lock+0x2f/0x70 [ 370.795677] ? driver_probe_device+0xd0/0xd0 [ 370.796576] __driver_attach_async_helper+0x1d/0xd0 [ 370.797318] ? driver_probe_device+0xd0/0xd0 [ 370.797957] async_schedule_node_domain+0xa5/0xc0 [ 370.798652] async_schedule_node+0x19/0x30 [ 370.799243] __driver_attach+0x246/0x290 [ 370.799828] ? driver_allows_async_probing+0xa0/0xa0 [ 370.800548] bus_for_each_dev+0x9d/0x130 [ 370.801132] driver_attach+0x22/0x30 [ 370.801666] bus_add_driver+0x290/0x340 [ 370.802246] driver_register+0x88/0x140 [ 370.802817] ? virtio_scsi_init+0x116/0x116 [ 370.803425] scsi_register_driver+0x1a/0x30 [ 370.804057] init_sd+0x184/0x226 [ 370.804533] do_one_initcall+0x71/0x3a0 [ 370.805107] kernel_init_freeable+0x39a/0x43a [ 370.805759] ? rest_init+0x150/0x150 [ 370.806283] kernel_init+0x26/0x230 [ 370.806799] ret_from_fork+0x1f/0x30 To fix the deadlock, move the async_schedule_dev outside device_lock, as we can see, in async_schedule_node_domain, the parameter of queue_work_node is system_unbound_wq, so it can accept concurrent operations. which will also not change the code logic, and will not lead to deadlock. Fixes: ef0ff68351be ("driver core: Probe devices asynchronously instead of the driver") Signed-off-by: Zhang Wensheng Link: https://lore.kernel.org/r/20220622074327.497102-1-zhangwensheng5@huawei.com Signed-off-by: Greg Kroah-Hartman

driver core: Delete driver_deferred_probe_check_state()

2022-06-10T13:57:54Z

The function is no longer used. So delete it. Tested-by: Geert Uytterhoeven Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20220601070707.3946847-10-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

Revert "driver core: Set default deferred_probe_timeout back to 0."

2022-06-10T13:57:54Z

This reverts commit 11f7e7ef553b6b93ac1aa74a3c2011b9cc8aeb61. Let's take another shot at getting deferred_probe_timeout=10 to work. Tested-by: Geert Uytterhoeven Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20220601070707.3946847-7-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Add wait_for_init_devices_probe helper function

2022-06-10T13:57:54Z

Some devices might need to be probed and bound successfully before the kernel boot sequence can finish and move on to init/userspace. For example, a network interface might need to be bound to be able to mount a NFS rootfs. With fw_devlink=on by default, some of these devices might be blocked from probing because they are waiting on a optional supplier that doesn't have a driver. While fw_devlink will eventually identify such devices and unblock the probing automatically, it might be too late by the time it unblocks the probing of devices. For example, the IP4 autoconfig might timeout before fw_devlink unblocks probing of the network interface. This function is available to temporarily try and probe all devices that have a driver even if some of their suppliers haven't been added or don't have drivers. The drivers can then decide which of the suppliers are optional vs mandatory and probe the device if possible. By the time this function returns, all such "best effort" probes are guaranteed to be completed. If a device successfully probes in this mode, we delete all fw_devlink discovered dependencies of that device where the supplier hasn't yet probed successfully because they have to be optional dependencies. This also means that some devices that aren't needed for init and could have waited for their optional supplier to probe (when the supplier's module is loaded later on) would end up probing prematurely with limited functionality. So call this function only when boot would fail without it. Tested-by: Geert Uytterhoeven Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20220601070707.3946847-5-saravanak@google.com Signed-off-by: Greg Kroah-Hartman

driver core: Set default deferred_probe_timeout back to 0.

2022-06-03T18:58:54Z

Since we had to effectively reverted commit 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires") in an earlier patch, a non-zero deferred_probe_timeout will break NFS rootfs mounting [1] again. So, set the default back to zero until we can fix that. [1] - https://lore.kernel.org/lkml/TYAPR01MB45443DF63B9EF29054F7C41FD8C60@TYAPR01MB4544.jpnprd01.prod.outlook.com/ Fixes: 2b28a1a84a0e ("driver core: Extend deferred probe timeout on driver registration") Cc: Mark Brown Cc: Rob Herring Reported-by: Nathan Chancellor Reported-by: Sebastian Andrzej Siewior Tested-by: Geert Uytterhoeven Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20220526034609.480766-3-saravanak@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds

driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction

2022-06-03T18:58:54Z

Mounting NFS rootfs was timing out when deferred_probe_timeout was non-zero [1]. This was because ip_auto_config() initcall times out waiting for the network interfaces to show up when deferred_probe_timeout was non-zero. While ip_auto_config() calls wait_for_device_probe() to make sure any currently running deferred probe work or asynchronous probe finishes, that wasn't sufficient to account for devices being deferred until deferred_probe_timeout. Commit 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires") tried to fix that by making sure wait_for_device_probe() waits for deferred_probe_timeout to expire before returning. However, if wait_for_device_probe() is called from the kernel_init() context: - Before deferred_probe_initcall() [2], it causes the boot process to hang due to a deadlock. - After deferred_probe_initcall() [3], it blocks kernel_init() from continuing till deferred_probe_timeout expires and beats the point of deferred_probe_timeout that's trying to wait for userspace to load modules. Neither of this is good. So revert the changes to wait_for_device_probe(). [1] - https://lore.kernel.org/lkml/TYAPR01MB45443DF63B9EF29054F7C41FD8C60@TYAPR01MB4544.jpnprd01.prod.outlook.com/ [2] - https://lore.kernel.org/lkml/YowHNo4sBjr9ijZr@dev-arch.thelio-3990X/ [3] - https://lore.kernel.org/lkml/Yo3WvGnNk3LvLb7R@linutronix.de/ Fixes: 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires") Cc: John Stultz Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: Hideaki YOSHIFUJI Cc: Jakub Kicinski Cc: Rob Herring Cc: Geert Uytterhoeven Cc: Yoshihiro Shimoda Cc: Robin Murphy Cc: Andy Shevchenko Cc: Sudeep Holla Cc: Andy Shevchenko Cc: Naresh Kamboju Cc: Basil Eljuse Cc: Ferry Toth Cc: Arnd Bergmann Cc: Anders Roxell Cc: linux-pm@vger.kernel.org Reported-by: Nathan Chancellor Reported-by: Sebastian Andrzej Siewior Tested-by: Geert Uytterhoeven Acked-by: John Stultz Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20220526034609.480766-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman Reviewed-by: Rafael J. Wysocki Signed-off-by: Linus Torvalds

Merge tag 'driver-core-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2022-06-03T18:48:47Z

Pull driver core updates from Greg KH: "Here is the set of driver core changes for 5.19-rc1. Lots of tiny driver core changes and cleanups happened this cycle, but the two major things are: - firmware_loader reorganization and additions including the ability to have XZ compressed firmware images and the ability for userspace to initiate the firmware load when it needs to, instead of being always initiated by the kernel. FPGA devices specifically want this ability to have their firmware changed over the lifetime of the system boot, and this allows them to work without having to come up with yet-another-custom-uapi interface for loading firmware for them. - physical location support added to sysfs so that devices that know this information, can tell userspace where they are located in a common way. Some ACPI devices already support this today, and more bus types should support this in the future. Smaller changes include: - driver_override api cleanups and fixes - error path cleanups and fixes - get_abi script fixes - deferred probe timeout changes. It's that last change that I'm the most worried about. It has been reported to cause boot problems for a number of systems, and I have a tested patch series that resolves this issue. But I didn't get it merged into my tree before 5.18-final came out, so it has not gotten any linux-next testing. I'll send the fixup patches (there are 2) as a follow-on series to this pull request. All have been tested in linux-next for weeks, with no reported issues other than the above-mentioned boot time-outs" * tag 'driver-core-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (55 commits) driver core: fix deadlock in __device_attach kernfs: Separate kernfs_pr_cont_buf and rename_lock. topology: Remove unused cpu_cluster_mask() driver core: Extend deferred probe timeout on driver registration MAINTAINERS: add Russ Weight as a firmware loader maintainer driver: base: fix UAF when driver_attach failed test_firmware: fix end of loop test in upload_read_show() driver core: location: Add "back" as a possible output for panel driver core: location: Free struct acpi_pld_info *pld driver core: Add "*" wildcard support to driver_async_probe cmdline param driver core: location: Check for allocations failure arch_topology: Trace the update thermal pressure kernfs: Rename kernfs_put_open_node to kernfs_unlink_open_file. export: fix string handling of namespace in EXPORT_SYMBOL_NS rpmsg: use local 'dev' variable rpmsg: Fix calling device_lock() on non-initialized device firmware_loader: describe 'module' parameter of firmware_upload_register() firmware_loader: Move definitions from sysfs_upload.h to sysfs.h firmware_loader: Fix configs for sysfs split selftests: firmware: Add firmware upload selftests ...

driver core: fix deadlock in __device_attach

2022-05-19T17:37:08Z

In __device_attach function, The lock holding logic is as follows: ... __device_attach device_lock(dev) // get lock dev async_schedule_dev(__device_attach_async_helper, dev); // func async_schedule_node async_schedule_node_domain(func) entry = kzalloc(sizeof(struct async_entry), GFP_ATOMIC); /* when fail or work limit, sync to execute func, but __device_attach_async_helper will get lock dev as well, which will lead to A-A deadlock. */ if (!entry || atomic_read(&entry_count) > MAX_WORK) { func; else queue_work_node(node, system_unbound_wq, &entry->work) device_unlock(dev) As shown above, when it is allowed to do async probes, because of out of memory or work limit, async work is not allowed, to do sync execute instead. it will lead to A-A deadlock because of __device_attach_async_helper getting lock dev. To fix the deadlock, move the async_schedule_dev outside device_lock, as we can see, in async_schedule_node_domain, the parameter of queue_work_node is system_unbound_wq, so it can accept concurrent operations. which will also not change the code logic, and will not lead to deadlock. Fixes: 765230b5f084 ("driver-core: add asynchronous probing support for drivers") Signed-off-by: Zhang Wensheng Link: https://lore.kernel.org/r/20220518074516.1225580-1-zhangwensheng5@huawei.com Signed-off-by: Greg Kroah-Hartman