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authorHans de Goede <hdegoede@redhat.com>2021-01-25 20:09:09 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2021-01-27 18:48:12 +0100
commit041142d7d25294c17d39552ae51c1d8d89434010 (patch)
treee834236ddb32e7f84ba2b64061493a761c63eff0 /drivers/acpi/Kconfig
parent84f9017c37c479c4f70456a645d24d2296ad2208 (diff)
ACPI: platform-profile: Fix possible deadlock in platform_profile_remove()
After a rmmod thinkpad_acpi, lockdep pointed out this possible deadlock: Our _show and _store sysfs attr functions get called with the kn->active lock held for the sysfs attr and then take the profile_lock. sysfs_remove_group() also takes the kn->active lock for the sysfs attr, so if we call it with the profile_lock held, then we get an ABBA deadlock. platform_profile_remove() must only be called by drivers which have first *successfully* called platform_profile_register(). Anything else is a driver bug. So the check for cur_profile being set before calling sysfs_remove_group() is not necessary and it can be dropped. It is safe to call sysfs_remove_group() without holding the profile_lock since the attr-group group cannot be re-added until after we clear cur_profile. Change platform_profile_remove() to only hold the profile_lock while clearing the cur_profile, fixing the deadlock. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/Kconfig')
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