linux/drivers/base/power, branch v3.9

PM / QoS: Avoid possible deadlock related to sysfs access

2013-04-01T23:25:24Z

Commit b81ea1b (PM / QoS: Fix concurrency issues and memory leaks in device PM QoS) put calls to pm_qos_sysfs_add_latency(), pm_qos_sysfs_add_flags(), pm_qos_sysfs_remove_latency(), and pm_qos_sysfs_remove_flags() under dev_pm_qos_mtx, which was a mistake, because it may lead to deadlocks in some situations. For example, if pm_qos_remote_wakeup_store() is run in parallel with dev_pm_qos_constraints_destroy(), they may deadlock in the following way: ====================================================== [ INFO: possible circular locking dependency detected ] 3.9.0-rc4-next-20130328-sasha-00014-g91a3267 #319 Tainted: G W ------------------------------------------------------- trinity-child6/12371 is trying to acquire lock: (s_active#54){++++.+}, at: [] sysfs_addrm_finish+0x31/0x60 but task is already holding lock: (dev_pm_qos_mtx){+.+.+.}, at: [] dev_pm_qos_constraints_destroy+0x23/0x250 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (dev_pm_qos_mtx){+.+.+.}: [] lock_acquire+0x1aa/0x240 [] __mutex_lock_common+0x59/0x5e0 [] mutex_lock_nested+0x3f/0x50 [] dev_pm_qos_update_flags+0x3f/0xc0 [] pm_qos_remote_wakeup_store+0x3f/0x70 [] dev_attr_store+0x13/0x20 [] sysfs_write_file+0xfa/0x150 [] __kernel_write+0x81/0x150 [] write_pipe_buf+0x4d/0x80 [] splice_from_pipe_feed+0x7c/0x120 [] __splice_from_pipe+0x45/0x80 [] splice_from_pipe+0x4c/0x70 [] default_file_splice_write+0x18/0x30 [] do_splice_from+0x83/0xb0 [] direct_splice_actor+0x1e/0x20 [] splice_direct_to_actor+0xe7/0x200 [] do_splice_direct+0x4c/0x70 [] do_sendfile+0x169/0x300 [] SyS_sendfile64+0x64/0xb0 [] tracesys+0xe1/0xe6 -> #0 (s_active#54){++++.+}: [] __lock_acquire+0x15bf/0x1e50 [] lock_acquire+0x1aa/0x240 [] sysfs_deactivate+0x122/0x1a0 [] sysfs_addrm_finish+0x31/0x60 [] sysfs_hash_and_remove+0x7f/0xb0 [] sysfs_unmerge_group+0x51/0x70 [] pm_qos_sysfs_remove_flags+0x14/0x20 [] __dev_pm_qos_hide_flags+0x30/0x70 [] dev_pm_qos_constraints_destroy+0x35/0x250 [] dpm_sysfs_remove+0x11/0x50 [] device_del+0x3f/0x1b0 [] device_unregister+0x48/0x60 [] usb_hub_remove_port_device+0x1c/0x20 [] hub_disconnect+0xdd/0x160 [] usb_unbind_interface+0x67/0x170 [] __device_release_driver+0x87/0xe0 [] device_release_driver+0x29/0x40 [] bus_remove_device+0x148/0x160 [] device_del+0x14f/0x1b0 [] usb_disable_device+0xf9/0x280 [] usb_set_configuration+0x268/0x840 [] usb_remove_store+0x4c/0x80 [] dev_attr_store+0x13/0x20 [] sysfs_write_file+0xfa/0x150 [] do_loop_readv_writev+0x4d/0x90 [] do_readv_writev+0xf9/0x1e0 [] vfs_writev+0x3a/0x60 [] SyS_writev+0x50/0xd0 [] tracesys+0xe1/0xe6 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(dev_pm_qos_mtx); lock(s_active#54); lock(dev_pm_qos_mtx); lock(s_active#54); *** DEADLOCK *** To avoid that, remove the calls to functions mentioned above from under dev_pm_qos_mtx and introduce a separate lock to prevent races between functions that add or remove device PM QoS sysfs attributes from happening. Reported-by: Sasha Levin Signed-off-by: Rafael J. Wysocki

PM / QoS: Remove device PM QoS sysfs attributes at the right place

2013-03-04T13:23:12Z

Device PM QoS sysfs attributes, if present during device removal, are removed from within device_pm_remove(), which is too late, since dpm_sysfs_remove() has already removed the whole attribute group they belonged to. However, moving the removal of those attributes to dpm_sysfs_remove() alone is not sufficient, because in theory they still can be re-added right after being removed by it (the device's driver is still bound to it at that point). For this reason, move the entire desctruction of device PM QoS constraints to dpm_sysfs_remove() and make it prevent any new constraints from being added after it has run. Also, move the initialization of the power.qos field in struct device to device_pm_init_common() and drop the no longer needed dev_pm_qos_constraints_init(). Reported-by: Sasha Levin Signed-off-by: Rafael J. Wysocki

PM / QoS: Fix concurrency issues and memory leaks in device PM QoS

2013-03-04T13:23:11Z

The current device PM QoS code assumes that certain functions will never be called in parallel with each other (for example, it is assumed that dev_pm_qos_expose_flags() won't be called in parallel with dev_pm_qos_hide_flags() for the same device and analogously for the latency limit), which may be overly optimistic. Moreover, dev_pm_qos_expose_flags() and dev_pm_qos_expose_latency_limit() leak memory in error code paths (req needs to be freed on errors) and __dev_pm_qos_drop_user_request() forgets to free the request. To fix the above issues put more things under the device PM QoS mutex to make them mutually exclusive and add the missing freeing of memory. Signed-off-by: Rafael J. Wysocki

pm / runtime: force memory allocation with no I/O during Runtime PM callbcack

2013-02-24T01:50:16Z

Apply the introduced memalloc_noio_save() and memalloc_noio_restore() to force memory allocation with no I/O during runtime_resume/runtime_suspend callback on device with the flag of 'memalloc_noio' set. Signed-off-by: Ming Lei Cc: "David S. Miller" Cc: Eric Dumazet Cc: David Decotigny Cc: Tom Herbert Cc: Ingo Molnar Cc: Jens Axboe Cc: Minchan Kim Cc: Alan Stern Cc: Oliver Neukum Cc: Jiri Kosina Cc: Mel Gorman Cc: KAMEZAWA Hiroyuki Cc: Michal Hocko Cc: Ingo Molnar Cc: Peter Zijlstra Cc: "Rafael J. Wysocki" Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pm / runtime: introduce pm_runtime_set_memalloc_noio()

2013-02-24T01:50:16Z

Introduce the flag memalloc_noio in 'struct dev_pm_info' to help PM core to teach mm not allocating memory with GFP_KERNEL flag for avoiding probable deadlock. As explained in the comment, any GFP_KERNEL allocation inside runtime_resume() or runtime_suspend() on any one of device in the path from one block or network device to the root device in the device tree may cause deadlock, the introduced pm_runtime_set_memalloc_noio() sets or clears the flag on device in the path recursively. Signed-off-by: Ming Lei Cc: Minchan Kim Cc: Alan Stern Cc: Oliver Neukum Cc: Jiri Kosina Cc: Mel Gorman Cc: KAMEZAWA Hiroyuki Cc: Michal Hocko Cc: Ingo Molnar Cc: Peter Zijlstra Cc: "Rafael J. Wysocki" Cc: Greg KH Cc: Jens Axboe Cc: "David S. Miller" Cc: Eric Dumazet Cc: David Decotigny Cc: Tom Herbert Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'usb-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

2013-02-21T20:20:00Z

Pull USB patches from Greg Kroah-Hartman: "Here's the big USB merge for 3.9-rc1 Nothing major, lots of gadget fixes, and of course, xhci stuff. All of this has been in linux-next for a while, with the exception of the last 3 patches, which were reverts of patches in the tree that caused problems, they went in yesterday." * tag 'usb-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (190 commits) Revert "USB: EHCI: make ehci-vt8500 a separate driver" Revert "USB: EHCI: make ehci-orion a separate driver" Revert "USB: update host controller Kconfig entries" USB: update host controller Kconfig entries USB: EHCI: make ehci-orion a separate driver USB: EHCI: make ehci-vt8500 a separate driver USB: usb-storage: unusual_devs update for Super TOP SATA bridge USB: ehci-omap: Fix autoloading of module USB: ehci-omap: Don't free gpios that we didn't request USB: option: add Huawei "ACM" devices using protocol = vendor USB: serial: fix null-pointer dereferences on disconnect USB: option: add Yota / Megafon M100-1 4g modem drivers/usb: add missing GENERIC_HARDIRQS dependencies USB: storage: properly handle the endian issues of idProduct testusb: remove all mentions of 'usbfs' usb: gadget: imx_udc: make it depend on BROKEN usb: omap_control_usb: fix compile warning ARM: OMAP: USB: Add phy binding information ARM: OMAP2: MUSB: Specify omap4 has mailbox ARM: OMAP: devices: create device for usb part of control module ...

Merge branch 'pm-cpufreq'

2013-02-15T12:59:07Z

* pm-cpufreq: (55 commits) cpufreq / intel_pstate: Fix 32 bit build cpufreq: conservative: Fix typos in comments cpufreq: ondemand: Fix typos in comments cpufreq: exynos: simplify .init() for setting policy->cpus cpufreq: kirkwood: Add a cpufreq driver for Marvell Kirkwood SoCs cpufreq/x86: Add P-state driver for sandy bridge. cpufreq_stats: do not remove sysfs files if frequency table is not present cpufreq: Do not track governor name for scaling drivers with internal governors. cpufreq: Only call cpufreq_out_of_sync() for driver that implement cpufreq_driver.target() cpufreq: Retrieve current frequency from scaling drivers with internal governors cpufreq: Fix locking issues cpufreq: Create a macro for unlock_policy_rwsem{read,write} cpufreq: Remove unused HOTPLUG_CPU code cpufreq: governors: Fix WARN_ON() for multi-policy platforms cpufreq: ondemand: Replace down_differential tuner with adj_up_threshold cpufreq / stats: Get rid of CPUFREQ_STATDEVICE_ATTR cpufreq: Don't check cpu_online(policy->cpu) cpufreq: add imx6q-cpufreq driver cpufreq: Don't remove sysfs link for policy->cpu cpufreq: Remove unnecessary use of policy->shared_type ...

PM: Introduce suspend state PM_SUSPEND_FREEZE

2013-02-09T21:30:44Z

PM_SUSPEND_FREEZE state is a general state that does not need any platform specific support, it equals frozen processes + suspended devices + idle processors. Compared with PM_SUSPEND_MEMORY, PM_SUSPEND_FREEZE saves less power because the system is still in a running state. PM_SUSPEND_FREEZE has less resume latency because it does not touch BIOS, and the processors are in idle state. Compared with RTPM/idle, PM_SUSPEND_FREEZE saves more power as 1. the processor has longer sleep time because processes are frozen. The deeper c-state the processor supports, more power saving we can get. 2. PM_SUSPEND_FREEZE uses system suspend code path, thus we can get more power saving from the devices that does not have good RTPM support. This state is useful for 1) platforms that do not have STR, or have a broken STR. 2) platforms that have an extremely low power idle state, which can be used to replace STR. The following describes how PM_SUSPEND_FREEZE state works. 1. echo freeze > /sys/power/state 2. the processes are frozen. 3. all the devices are suspended. 4. all the processors are blocked by a wait queue 5. all the processors idles and enters (Deep) c-state. 6. an interrupt fires. 7. a processor is woken up and handles the irq. 8. if it is a general event, a) the irq handler runs and quites. b) goto step 4. 9. if it is a real wake event, say, power button pressing, keyboard touch, mouse moving, a) the irq handler runs and activate the wakeup source b) wakeup_source_activate() notifies the wait queue. c) system starts resuming from PM_SUSPEND_FREEZE 10. all the devices are resumed. 11. all the processes are unfrozen. 12. system is back to working. Known Issue: The wakeup of this new PM_SUSPEND_FREEZE state may behave differently from the previous suspend state. Take ACPI platform for example, there are some GPEs that only enabled when the system is in sleep state, to wake the system backk from S3/S4. But we are not touching these GPEs during transition to PM_SUSPEND_FREEZE. This means we may lose some wake event. But on the other hand, as we do not disable all the Interrupts during PM_SUSPEND_FREEZE, we may get some extra "wakeup" Interrupts, that are not available for S3/S4. The patches has been tested on an old Sony laptop, and here are the results: Average Power: 1. RPTM/idle for half an hour: 14.8W, 12.6W, 14.1W, 12.5W, 14.4W, 13.2W, 12.9W 2. Freeze for half an hour: 11W, 10.4W, 9.4W, 11.3W 10.5W 3. RTPM/idle for three hours: 11.6W 4. Freeze for three hours: 10W 5. Suspend to Memory: 0.5~0.9W Average Resume Latency: 1. RTPM/idle with a black screen: (From pressing keyboard to screen back) Less than 0.2s 2. Freeze: (From pressing power button to screen back) 2.50s 3. Suspend to Memory: (From pressing power button to screen back) 4.33s >From the results, we can see that all the platforms should benefit from this patch, even if it does not have Low Power S0. Signed-off-by: Zhang Rui Signed-off-by: Rafael J. Wysocki

PM / OPP: Export more symbols for module usage

2013-02-01T23:01:16Z

Export cpufreq helpers in OPP to make the cpufreq-core0 and highbank-cpufreq drivers loadable as modules. Signed-off-by: Mark Langsdorf Signed-off-by: Nishanth Menon Acked-by: Shawn Guo Signed-off-by: Rafael J. Wysocki

PM / OPP: switch exported symbols to GPL variant

2013-02-01T23:01:15Z

We are GPLV2 library, so be clear in the symbols exported as well. Signed-off-by: Nishanth Menon Acked-by: Shawn Guo Signed-off-by: Rafael J. Wysocki