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define TOOL_templ
  include $(1)/Makefile
  $(1) $(1)%: BUILD_DIR := $(1)
  $(1) $(1)%: CFLAGS += $$($(1)-eflags)
  $(1)_prehook:
	$(Q)echo "$(bold)$(WHAT) $(1):$(normal)"
  $(1): $(1)_prehook $$($(1)-lex) $$($(1)-yaac) $$(patsubst %.o,$(1)/%.o,$$($(1)-objs))
  $(1)_clean: $(1)_clean_custom
	$(Q)$$(call RM,$(1)/*.o $(1)/$(1) $(1)/*.gz)
  $(1)_do_install:
	$(Q)$$(call INSTX,$(1)/$(1),$$(DESTDIR)$$(SBINDIR))
	$(Q)$(GZIP) $(1).8 > $(1)/$(1).8.gz
	$(Q)$$(call INST,$(1)/$(1).8.gz,$$(DESTDIR)$$(MAN8DIR))
	$(Q)$$(foreach file,$$($(1)-confs),$$(call INST,$$(file),$$(DESTDIR)$$(ETCDIRE));)
  $(1)_install: $(1)_do_install $(1)_post_install
  $(1)_uninstall: $(1)_uninstall_custom
	$(Q)$$(call RM,$$(DESTDIR)$$(SBINDIR)/$(1))
	$(Q)$$(call RM,$$(DESTDIR)$$(MAN8DIR)/$(1).8.gz)
  $(1)/%.yy.o: $(1)/%.yy.c
	$$(CCQ) $$(CFLAGS) -o $$@ -c $$<
  $(1)/%.tab.o: $(1)/%.tab.c
	$$(CCQ) $$(CFLAGS) -o $$@ -c $$<
  $(1)/%.o: %.c %.h
	$$(CHECK) $$(CFLAGS) $$(CHECKFLAGS) $$<
	$$(CCQ) $$(CFLAGS) -o $(1)/$$(shell basename $$@) -c $$<
  $(1)/%.o: %.c
	$$(CHECK) $$(CFLAGS) $$(CHECKFLAGS) $$<
	$$(CCQ) $$(CFLAGS) -o $(1)/$$(shell basename $$@) -c $$<
endef
/td> parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'tools/lib/find_bit.c')