linux/drivers/base/core.c

2022 lines
51 KiB

Driver core: add notification of bus events I finally did as you suggested and added the notifier to the struct bus_type itself. There are still problems to be expected is something attaches to a bus type where the code can hook in different struct device sub-classes (which is imho a big bogosity but I won't even try to argue that case now) but it will solve nicely a number of issues I've had so far. That also means that clients interested in registering for such notifications have to do it before devices are added and after bus types are registered. Fortunately, most bus types that matter for the various usage scenarios I have in mind are registerd at postcore_initcall time, which means I have a really nice spot at arch_initcall time to add my notifiers. There are 4 notifications provided. Device being added (before hooked to the bus) and removed (failure of previous case or after being unhooked from the bus), along with driver being bound to a device and about to be unbound. The usage I have for these are: - The 2 first ones are used to maintain a struct device_ext that is hooked to struct device.firmware_data. This structure contains for now a pointer to the Open Firmware node related to the device (if any), the NUMA node ID (for quick access to it) and the DMA operations pointers & iommu table instance for DMA to/from this device. For bus types I own (like IBM VIO or EBUS), I just maintain that structure directly from the bus code when creating the devices. But for bus types managed by generic code like PCI or platform (actually, of_platform which is a variation of platform linked to Open Firmware device-tree), I need this notifier. - The other two ones have a completely different usage scenario. I have cases where multiple devices and their drivers depend on each other. For example, the IBM EMAC network driver needs to attach to a MAL DMA engine which is a separate device, and a PHY interface which is also a separate device. They are all of_platform_device's (well, about to be with my upcoming patches) but there is no say in what precise order the core will "probe" them and instanciate the various modules. The solution I found for that is to have the drivers for emac to use multithread_probe, and wait for a driver to be bound to the target MAL and PHY control devices (the device-tree contains reference to the MAL and PHY interface nodes, which I can then match to of_platform_devices). Right now, I've been polling, but with that notifier, I can more cleanly wait (with a timeout of course). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-10-25 13:44:59 +10:00
driver-core: fix race condition in get_device_parent() sysfs is creating several devices in cuse class concurrently and with CONFIG_SYSFS_DEPRECATED turned off, it triggers the following oops. BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 IP: [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 PGD 75bb067 PUD 75be067 PMD 0 Oops: 0000 [#1] PREEMPT SMP last sysfs file: /sys/devices/system/cpu/cpu7/topology/core_siblings CPU 1 Modules linked in: cuse fuse Pid: 4737, comm: osspd Not tainted 2.6.31-work #77 RIP: 0010:[<ffffffff81158b0a>] [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 RSP: 0018:ffff88000042f8f8 EFLAGS: 00010296 RAX: ffff88000042ffd8 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880007eef660 RDI: 0000000000000001 RBP: ffff88000042f918 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff81158b0a R12: ffff88000042f928 R13: 00000000fffffff4 R14: 0000000000000000 R15: ffff88000042f9a0 FS: 00007fe93905a950(0000) GS:ffff880008600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000038 CR3: 00000000077c9000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process osspd (pid: 4737, threadinfo ffff88000042e000, task ffff880007eef040) Stack: ffff880005da10e8 0000000011cc8d6e ffff88000042f928 ffff880003d28a28 <0> ffff88000042f988 ffffffff811592d7 0000000000000000 0000000000000000 <0> 0000000000000000 0000000000000000 ffff88000042f958 0000000011cc8d6e Call Trace: [<ffffffff811592d7>] create_dir+0x67/0xe0 [<ffffffff811593a8>] sysfs_create_dir+0x58/0xb0 [<ffffffff8128ca7c>] ? kobject_add_internal+0xcc/0x220 [<ffffffff812942e1>] ? vsnprintf+0x3c1/0xb90 [<ffffffff8128cab7>] kobject_add_internal+0x107/0x220 [<ffffffff8128cd37>] kobject_add_varg+0x47/0x80 [<ffffffff8128ce53>] kobject_add+0x53/0x90 [<ffffffff81357d84>] device_add+0xd4/0x690 [<ffffffff81356c2b>] ? dev_set_name+0x4b/0x70 [<ffffffffa001a884>] cuse_process_init_reply+0x2b4/0x420 [cuse] ... The problem is that kobject_add_internal() first adds a kobject to the kset and then try to create sysfs directory for it. If the creation fails, it remove the kobject from the kset. get_device_parent() accesses class_dirs kset while only holding class_dirs.list_lock to see whether the cuse class dir exists. But when it exists, it may not have finished initialization yet or may fail and get removed soon. In the above case, the former happened so the second one ends up trying to create subdirectory under NULL sysfs_dirent. Fix it by grabbing a mutex in get_device_parent(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Colin Guthrie <cguthrie@mandriva.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-02-05 17:57:02 +09:00
Driver-core: Always create class directories for classses that support namespaces. This fixes the regression in 2.6.35-rcX where bluetooth network devices would fail to be deleted from sysfs, causing their destruction and recreation to fail. In addition this fixes the mac80211_hwsim driver where it would leave around sysfs files when the driver was removed. This problem is discussed at https://bugzilla.kernel.org/show_bug.cgi?id=16257 The reason for the regression is that the network namespace support added to sysfs expects and requires that network devices be put in directories that can contain only network devices. Today get_device_parent almost provides that guarantee for all class devices, except for a specific exception when the parent of a class devices is a class device. It would be nice to simply remove that arguably incorrect special case, but apparently the input devices depend on it being there. So I have only removed it for class devices with network namespace support. Which today are the network devices. It has been suggested that a better fix would be to change the parent device from a class device to a bus device, which in the case of the bluetooth driver would change /sys/class/bluetooth to /sys/bus/bluetoth, I can not see how we would avoid significant userspace breakage if we were to make that change. Adding an extra directory in the path to the device will also be userspace visible but it is much less likely to break things. Everything is still accessible from /sys/class (for example), and it fixes two bugs. Adding an extra directory fixes a 3 year old regression introduced with the new sysfs layout that makes it impossible to rename bnep0 network devices to names that conflict with hci device attributes like hci_revsion. Adding an additional directory removes the new failure modes introduced by the network namespace code. If it weren't for the regession in the renaming of network devices I would figure out how to just make the sysfs code deal with this configuration of devices. In summary this patch fixes regressions by changing: "/sys/class/bluetooth/hci0/bnep0" to "/sys/class/bluetooth/hci0/net/bnep0". Reported-by: Johannes Berg <johannes@sipsolutions.net> Reported-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-24 22:43:35 -07:00
driver-core: fix race condition in get_device_parent() sysfs is creating several devices in cuse class concurrently and with CONFIG_SYSFS_DEPRECATED turned off, it triggers the following oops. BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 IP: [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 PGD 75bb067 PUD 75be067 PMD 0 Oops: 0000 [#1] PREEMPT SMP last sysfs file: /sys/devices/system/cpu/cpu7/topology/core_siblings CPU 1 Modules linked in: cuse fuse Pid: 4737, comm: osspd Not tainted 2.6.31-work #77 RIP: 0010:[<ffffffff81158b0a>] [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 RSP: 0018:ffff88000042f8f8 EFLAGS: 00010296 RAX: ffff88000042ffd8 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880007eef660 RDI: 0000000000000001 RBP: ffff88000042f918 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff81158b0a R12: ffff88000042f928 R13: 00000000fffffff4 R14: 0000000000000000 R15: ffff88000042f9a0 FS: 00007fe93905a950(0000) GS:ffff880008600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000038 CR3: 00000000077c9000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process osspd (pid: 4737, threadinfo ffff88000042e000, task ffff880007eef040) Stack: ffff880005da10e8 0000000011cc8d6e ffff88000042f928 ffff880003d28a28 <0> ffff88000042f988 ffffffff811592d7 0000000000000000 0000000000000000 <0> 0000000000000000 0000000000000000 ffff88000042f958 0000000011cc8d6e Call Trace: [<ffffffff811592d7>] create_dir+0x67/0xe0 [<ffffffff811593a8>] sysfs_create_dir+0x58/0xb0 [<ffffffff8128ca7c>] ? kobject_add_internal+0xcc/0x220 [<ffffffff812942e1>] ? vsnprintf+0x3c1/0xb90 [<ffffffff8128cab7>] kobject_add_internal+0x107/0x220 [<ffffffff8128cd37>] kobject_add_varg+0x47/0x80 [<ffffffff8128ce53>] kobject_add+0x53/0x90 [<ffffffff81357d84>] device_add+0xd4/0x690 [<ffffffff81356c2b>] ? dev_set_name+0x4b/0x70 [<ffffffffa001a884>] cuse_process_init_reply+0x2b4/0x420 [cuse] ... The problem is that kobject_add_internal() first adds a kobject to the kset and then try to create sysfs directory for it. If the creation fails, it remove the kobject from the kset. get_device_parent() accesses class_dirs kset while only holding class_dirs.list_lock to see whether the cuse class dir exists. But when it exists, it may not have finished initialization yet or may fail and get removed soon. In the above case, the former happened so the second one ends up trying to create subdirectory under NULL sysfs_dirent. Fix it by grabbing a mutex in get_device_parent(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Colin Guthrie <cguthrie@mandriva.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-02-05 17:57:02 +09:00
driver-core: fix race condition in get_device_parent() sysfs is creating several devices in cuse class concurrently and with CONFIG_SYSFS_DEPRECATED turned off, it triggers the following oops. BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 IP: [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 PGD 75bb067 PUD 75be067 PMD 0 Oops: 0000 [#1] PREEMPT SMP last sysfs file: /sys/devices/system/cpu/cpu7/topology/core_siblings CPU 1 Modules linked in: cuse fuse Pid: 4737, comm: osspd Not tainted 2.6.31-work #77 RIP: 0010:[<ffffffff81158b0a>] [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 RSP: 0018:ffff88000042f8f8 EFLAGS: 00010296 RAX: ffff88000042ffd8 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880007eef660 RDI: 0000000000000001 RBP: ffff88000042f918 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff81158b0a R12: ffff88000042f928 R13: 00000000fffffff4 R14: 0000000000000000 R15: ffff88000042f9a0 FS: 00007fe93905a950(0000) GS:ffff880008600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000038 CR3: 00000000077c9000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process osspd (pid: 4737, threadinfo ffff88000042e000, task ffff880007eef040) Stack: ffff880005da10e8 0000000011cc8d6e ffff88000042f928 ffff880003d28a28 <0> ffff88000042f988 ffffffff811592d7 0000000000000000 0000000000000000 <0> 0000000000000000 0000000000000000 ffff88000042f958 0000000011cc8d6e Call Trace: [<ffffffff811592d7>] create_dir+0x67/0xe0 [<ffffffff811593a8>] sysfs_create_dir+0x58/0xb0 [<ffffffff8128ca7c>] ? kobject_add_internal+0xcc/0x220 [<ffffffff812942e1>] ? vsnprintf+0x3c1/0xb90 [<ffffffff8128cab7>] kobject_add_internal+0x107/0x220 [<ffffffff8128cd37>] kobject_add_varg+0x47/0x80 [<ffffffff8128ce53>] kobject_add+0x53/0x90 [<ffffffff81357d84>] device_add+0xd4/0x690 [<ffffffff81356c2b>] ? dev_set_name+0x4b/0x70 [<ffffffffa001a884>] cuse_process_init_reply+0x2b4/0x420 [cuse] ... The problem is that kobject_add_internal() first adds a kobject to the kset and then try to create sysfs directory for it. If the creation fails, it remove the kobject from the kset. get_device_parent() accesses class_dirs kset while only holding class_dirs.list_lock to see whether the cuse class dir exists. But when it exists, it may not have finished initialization yet or may fail and get removed soon. In the above case, the former happened so the second one ends up trying to create subdirectory under NULL sysfs_dirent. Fix it by grabbing a mutex in get_device_parent(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Colin Guthrie <cguthrie@mandriva.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-02-05 17:57:02 +09:00
driver-core: fix race condition in get_device_parent() sysfs is creating several devices in cuse class concurrently and with CONFIG_SYSFS_DEPRECATED turned off, it triggers the following oops. BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 IP: [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 PGD 75bb067 PUD 75be067 PMD 0 Oops: 0000 [#1] PREEMPT SMP last sysfs file: /sys/devices/system/cpu/cpu7/topology/core_siblings CPU 1 Modules linked in: cuse fuse Pid: 4737, comm: osspd Not tainted 2.6.31-work #77 RIP: 0010:[<ffffffff81158b0a>] [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 RSP: 0018:ffff88000042f8f8 EFLAGS: 00010296 RAX: ffff88000042ffd8 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880007eef660 RDI: 0000000000000001 RBP: ffff88000042f918 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff81158b0a R12: ffff88000042f928 R13: 00000000fffffff4 R14: 0000000000000000 R15: ffff88000042f9a0 FS: 00007fe93905a950(0000) GS:ffff880008600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000038 CR3: 00000000077c9000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process osspd (pid: 4737, threadinfo ffff88000042e000, task ffff880007eef040) Stack: ffff880005da10e8 0000000011cc8d6e ffff88000042f928 ffff880003d28a28 <0> ffff88000042f988 ffffffff811592d7 0000000000000000 0000000000000000 <0> 0000000000000000 0000000000000000 ffff88000042f958 0000000011cc8d6e Call Trace: [<ffffffff811592d7>] create_dir+0x67/0xe0 [<ffffffff811593a8>] sysfs_create_dir+0x58/0xb0 [<ffffffff8128ca7c>] ? kobject_add_internal+0xcc/0x220 [<ffffffff812942e1>] ? vsnprintf+0x3c1/0xb90 [<ffffffff8128cab7>] kobject_add_internal+0x107/0x220 [<ffffffff8128cd37>] kobject_add_varg+0x47/0x80 [<ffffffff8128ce53>] kobject_add+0x53/0x90 [<ffffffff81357d84>] device_add+0xd4/0x690 [<ffffffff81356c2b>] ? dev_set_name+0x4b/0x70 [<ffffffffa001a884>] cuse_process_init_reply+0x2b4/0x420 [cuse] ... The problem is that kobject_add_internal() first adds a kobject to the kset and then try to create sysfs directory for it. If the creation fails, it remove the kobject from the kset. get_device_parent() accesses class_dirs kset while only holding class_dirs.list_lock to see whether the cuse class dir exists. But when it exists, it may not have finished initialization yet or may fail and get removed soon. In the above case, the former happened so the second one ends up trying to create subdirectory under NULL sysfs_dirent. Fix it by grabbing a mutex in get_device_parent(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Colin Guthrie <cguthrie@mandriva.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-02-05 17:57:02 +09:00
driver-core: fix race condition in get_device_parent() sysfs is creating several devices in cuse class concurrently and with CONFIG_SYSFS_DEPRECATED turned off, it triggers the following oops. BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 IP: [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 PGD 75bb067 PUD 75be067 PMD 0 Oops: 0000 [#1] PREEMPT SMP last sysfs file: /sys/devices/system/cpu/cpu7/topology/core_siblings CPU 1 Modules linked in: cuse fuse Pid: 4737, comm: osspd Not tainted 2.6.31-work #77 RIP: 0010:[<ffffffff81158b0a>] [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0 RSP: 0018:ffff88000042f8f8 EFLAGS: 00010296 RAX: ffff88000042ffd8 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880007eef660 RDI: 0000000000000001 RBP: ffff88000042f918 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff81158b0a R12: ffff88000042f928 R13: 00000000fffffff4 R14: 0000000000000000 R15: ffff88000042f9a0 FS: 00007fe93905a950(0000) GS:ffff880008600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000038 CR3: 00000000077c9000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process osspd (pid: 4737, threadinfo ffff88000042e000, task ffff880007eef040) Stack: ffff880005da10e8 0000000011cc8d6e ffff88000042f928 ffff880003d28a28 <0> ffff88000042f988 ffffffff811592d7 0000000000000000 0000000000000000 <0> 0000000000000000 0000000000000000 ffff88000042f958 0000000011cc8d6e Call Trace: [<ffffffff811592d7>] create_dir+0x67/0xe0 [<ffffffff811593a8>] sysfs_create_dir+0x58/0xb0 [<ffffffff8128ca7c>] ? kobject_add_internal+0xcc/0x220 [<ffffffff812942e1>] ? vsnprintf+0x3c1/0xb90 [<ffffffff8128cab7>] kobject_add_internal+0x107/0x220 [<ffffffff8128cd37>] kobject_add_varg+0x47/0x80 [<ffffffff8128ce53>] kobject_add+0x53/0x90 [<ffffffff81357d84>] device_add+0xd4/0x690 [<ffffffff81356c2b>] ? dev_set_name+0x4b/0x70 [<ffffffffa001a884>] cuse_process_init_reply+0x2b4/0x420 [cuse] ... The problem is that kobject_add_internal() first adds a kobject to the kset and then try to create sysfs directory for it. If the creation fails, it remove the kobject from the kset. get_device_parent() accesses class_dirs kset while only holding class_dirs.list_lock to see whether the cuse class dir exists. But when it exists, it may not have finished initialization yet or may fail and get removed soon. In the above case, the former happened so the second one ends up trying to create subdirectory under NULL sysfs_dirent. Fix it by grabbing a mutex in get_device_parent(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Colin Guthrie <cguthrie@mandriva.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-02-05 17:57:02 +09:00
Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev Devtmpfs lets the kernel create a tmpfs instance called devtmpfs very early at kernel initialization, before any driver-core device is registered. Every device with a major/minor will provide a device node in devtmpfs. Devtmpfs can be changed and altered by userspace at any time, and in any way needed - just like today's udev-mounted tmpfs. Unmodified udev versions will run just fine on top of it, and will recognize an already existing kernel-created device node and use it. The default node permissions are root:root 0600. Proper permissions and user/group ownership, meaningful symlinks, all other policy still needs to be applied by userspace. If a node is created by devtmps, devtmpfs will remove the device node when the device goes away. If the device node was created by userspace, or the devtmpfs created node was replaced by userspace, it will no longer be removed by devtmpfs. If it is requested to auto-mount it, it makes init=/bin/sh work without any further userspace support. /dev will be fully populated and dynamic, and always reflect the current device state of the kernel. With the commonly used dynamic device numbers, it solves the problem where static devices nodes may point to the wrong devices. It is intended to make the initial bootup logic simpler and more robust, by de-coupling the creation of the inital environment, to reliably run userspace processes, from a complex userspace bootstrap logic to provide a working /dev. Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Jan Blunck <jblunck@suse.de> Tested-By: Harald Hoyer <harald@redhat.com> Tested-By: Scott James Remnant <scott@ubuntu.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-04-30 15:23:42 +02:00
Driver Core: devtmpfs - kernel-maintained tmpfs-based /dev Devtmpfs lets the kernel create a tmpfs instance called devtmpfs very early at kernel initialization, before any driver-core device is registered. Every device with a major/minor will provide a device node in devtmpfs. Devtmpfs can be changed and altered by userspace at any time, and in any way needed - just like today's udev-mounted tmpfs. Unmodified udev versions will run just fine on top of it, and will recognize an already existing kernel-created device node and use it. The default node permissions are root:root 0600. Proper permissions and user/group ownership, meaningful symlinks, all other policy still needs to be applied by userspace. If a node is created by devtmps, devtmpfs will remove the device node when the device goes away. If the device node was created by userspace, or the devtmpfs created node was replaced by userspace, it will no longer be removed by devtmpfs. If it is requested to auto-mount it, it makes init=/bin/sh work without any further userspace support. /dev will be fully populated and dynamic, and always reflect the current device state of the kernel. With the commonly used dynamic device numbers, it solves the problem where static devices nodes may point to the wrong devices. It is intended to make the initial bootup logic simpler and more robust, by de-coupling the creation of the inital environment, to reliably run userspace processes, from a complex userspace bootstrap logic to provide a working /dev. Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Jan Blunck <jblunck@suse.de> Tested-By: Harald Hoyer <harald@redhat.com> Tested-By: Scott James Remnant <scott@ubuntu.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-04-30 15:23:42 +02:00
driver core / PM: move the calling to device_pm_remove behind the calling to bus_remove_device We hit an hang issue when removing a mmc device on Medfield Android phone by sysfs interface. device_pm_remove will call pm_runtime_remove which would disable runtime PM of the device. After that pm_runtime_get* or pm_runtime_put* will be ignored. So if we disable the runtime PM before device really be removed, drivers' _remove callback may access HW even pm_runtime_get* fails. That is bad. Consider below call sequence when removing a device: device_del => device_pm_remove => class_intf->remove_dev(dev, class_intf) => pm_runtime_get_sync/put_sync => bus_remove_device => device_release_driver => pm_runtime_get_sync/put_sync remove_dev might call pm_runtime_get_sync/put_sync. Then, generic device_release_driver also calls pm_runtime_get_sync/put_sync. Since device_del => device_pm_remove firstly, later _get_sync wouldn't really wake up the device. I git log -p to find the patch which moves the calling to device_pm_remove ahead. It's below patch: commit 775b64d2b6ca37697de925f70799c710aab5849a Author: Rafael J. Wysocki <rjw@sisk.pl> Date: Sat Jan 12 20:40:46 2008 +0100 PM: Acquire device locks on suspend This patch reorganizes the way suspend and resume notifications are sent to drivers. The major changes are that now the PM core acquires every device semaphore before calling the methods, and calls to device_add() during suspends will fail, while calls to device_del() during suspends will block. It also provides a way to safely remove a suspended device with the help of the PM core, by using the device_pm_schedule_removal() callback introduced specifically for this purpose, and updates two drivers (msr and cpuid) that need to use it. As device_pm_schedule_removal is deleted by another patch, we need also revert other parts of the patch, i.e. move the calling of device_pm_remove after the calling to bus_remove_device. Signed-off-by: LongX Zhang <longx.zhang@intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-10-25 00:21:28 +02:00
drivercore: Add driver probe deferral mechanism Allow drivers to report at probe time that they cannot get all the resources required by the device, and should be retried at a later time. This should completely solve the problem of getting devices initialized in the right order. Right now this is mostly handled by mucking about with initcall ordering which is a complete hack, and doesn't even remotely handle the case where device drivers are in modules. This approach completely sidesteps the issues by allowing driver registration to occur in any order, and any driver can request to be retried after a few more other drivers get probed. v4: - Integrate Manjunath's addition of a separate workqueue - Change -EAGAIN to -EPROBE_DEFER for drivers to trigger deferral - Update comment blocks to reflect how the code really works v3: - Hold off workqueue scheduling until late_initcall so that the bulk of driver probes are complete before we start retrying deferred devices. - Tested with simple use cases. Still needs more testing though. Using it to get rid of the gpio early_initcall madness, or to replace the ASoC internal probe deferral code would be ideal. v2: - added locking so it should no longer be utterly broken in that regard - remove device from deferred list at device_del time. - Still completely untested with any real use case, but has been boot tested. Signed-off-by: Grant Likely <grant.likely@secretlab.ca> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dilan Lee <dilee@nvidia.com> Cc: Manjunath GKondaiah <manjunath.gkondaiah@linaro.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Tony Lindgren <tony@atomide.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Acked-by: David Daney <david.daney@cavium.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-03-05 08:47:41 -07:00