Revision 6941051d3028963c3b0b3fcdd0815f2b51b957bb authored by Sudeep Holla on 18 October 2019, 10:58:15 UTC, committed by Rafael J. Wysocki on 22 October 2019, 16:07:30 UTC
Scheduled policy update work may end up racing with the freeing of the policy and unregistering the driver. One possible race is as below, where the cpufreq_driver is unregistered, but the scheduled work gets executed at later stage when, cpufreq_driver is NULL (i.e. after freeing the policy and driver). Unable to handle kernel NULL pointer dereference at virtual address 0000001c pgd = (ptrval) [0000001c] *pgd=80000080204003, *pmd=00000000 Internal error: Oops: 206 [#1] SMP THUMB2 Modules linked in: CPU: 0 PID: 34 Comm: kworker/0:1 Not tainted 5.4.0-rc3-00006-g67f5a8081a4b #86 Hardware name: ARM-Versatile Express Workqueue: events handle_update PC is at cpufreq_set_policy+0x58/0x228 LR is at dev_pm_qos_read_value+0x77/0xac Control: 70c5387d Table: 80203000 DAC: fffffffd Process kworker/0:1 (pid: 34, stack limit = 0x(ptrval)) (cpufreq_set_policy) from (refresh_frequency_limits.part.24+0x37/0x48) (refresh_frequency_limits.part.24) from (handle_update+0x2f/0x38) (handle_update) from (process_one_work+0x16d/0x3cc) (process_one_work) from (worker_thread+0xff/0x414) (worker_thread) from (kthread+0xff/0x100) (kthread) from (ret_from_fork+0x11/0x28) Fixes: 67d874c3b2c6 ("cpufreq: Register notifiers with the PM QoS framework") Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> [ rjw: Cancel the work before dropping the QoS requests ] Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
1 parent 2aac8bd
Makefile.clean
# SPDX-License-Identifier: GPL-2.0
# ==========================================================================
# Cleaning up
# ==========================================================================
src := $(obj)
PHONY := __clean
__clean:
include scripts/Kbuild.include
# The filename Kbuild has precedence over Makefile
kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile)
# Figure out what we need to build from the various variables
# ==========================================================================
subdir-ymn := $(sort $(subdir-y) $(subdir-m) $(subdir-) \
$(patsubst %/,%, $(filter %/, $(obj-y) $(obj-m) $(obj-))))
# Add subdir path
subdir-ymn := $(addprefix $(obj)/,$(subdir-ymn))
# build a list of files to remove, usually relative to the current
# directory
__clean-files := $(extra-y) $(extra-m) $(extra-) \
$(always) $(targets) $(clean-files) \
$(hostprogs-y) $(hostprogs-m) $(hostprogs-) \
$(hostlibs-y) $(hostlibs-m) $(hostlibs-) \
$(hostcxxlibs-y) $(hostcxxlibs-m)
__clean-files := $(filter-out $(no-clean-files), $(__clean-files))
# clean-files is given relative to the current directory, unless it
# starts with $(objtree)/ (which means "./", so do not add "./" unless
# you want to delete a file from the toplevel object directory).
__clean-files := $(wildcard \
$(addprefix $(obj)/, $(filter-out $(objtree)/%, $(__clean-files))) \
$(filter $(objtree)/%, $(__clean-files)))
# ==========================================================================
quiet_cmd_clean = CLEAN $(obj)
cmd_clean = rm -rf $(__clean-files)
__clean: $(subdir-ymn)
ifneq ($(strip $(__clean-files)),)
$(call cmd,clean)
endif
@:
# ===========================================================================
# Generic stuff
# ===========================================================================
# Descending
# ---------------------------------------------------------------------------
PHONY += $(subdir-ymn)
$(subdir-ymn):
$(Q)$(MAKE) $(clean)=$@
.PHONY: $(PHONY)
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