# Makefile for llmnrd # # Copyright (C) 2014-2015 Tobias Klauser VERSION = 0.1-rc1 # llmnrd binary D_P = llmnrd D_OBJS = llmnr.o iface.o socket.o util.o llmnrd.o D_LIBS = -lpthread # llmnr-query binary Q_P = llmnr-query Q_OBJS = util.o llmnr-query.o Q_LIBS = CC = $(CROSS_COMPILE)gcc INSTALL = install CFLAGS ?= -W -Wall -O2 LDFLAGS ?= ifeq ($(shell git rev-parse > /dev/null 2>&1; echo $$?), 0) GIT_VERSION = "(git id $(shell git describe --always))" else GIT_VERSION = endif CFLAGS += -DVERSION_STRING=\"v$(VERSION)\" -DGIT_VERSION=\"$(GIT_VERSION)\" ifeq ($(DEBUG), 1) CFLAGS += -g -DDEBUG endif Q ?= @ CCQ = $(Q)echo " CC $<" && $(CC) LDQ = $(Q)echo " LD $@" && $(CC) prefix ?= /usr/local BINDIR = $(prefix)/bin SBINDIR = $(prefix)/sbin DESTDIR = all: $(D_P) $(Q_P) $(D_P): $(D_OBJS) $(LDQ) $(LDFLAGS) -o $@ $(D_OBJS) $(D_LIBS) $(Q_P): $(Q_OBJS) $(LDQ) $(LDFLAGS) -o $@ $(Q_OBJS) $(Q_LIBS) %.o: %.c %.h $(CCQ) $(CFLAGS) -o $@ -c $< %.o: %.c $(CCQ) $(CFLAGS) -o $@ -c $< install_$(D_P): $(D_P) @echo " INSTALL $(D_P)" @$(INSTALL) -d -m 755 $(DESTDIR)$(SBINDIR) @$(INSTALL) -m 755 $(D_P) $(SBINDIR)/$(D_P) install_$(Q_P): $(Q_P) @echo " INSTALL $(Q_P)" @$(INSTALL) -d -m 755 $(DESTDIR)$(BINDIR) @$(INSTALL) -m 755 $(Q_P) $(BINDIR)/$(Q_P) install: install_$(D_P) install_$(Q_P) clean: @echo " CLEAN" @rm -f $(D_OBJS) $(D_P) @rm -f $(Q_OBJS) $(Q_P) > net-next plumbingsTobias Klauser
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authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /net/ieee802154
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 'net/ieee802154')