Tejun Heo 215840ab83 rculist: list_first_or_null_rcu() should use list_entry_rcu() ... commit c34ac00cae upstream. list_first_or_null() should test whether the list is empty and return pointer to the first entry if not in a RCU safe manner. It's broken in several ways. * It compares __kernel @__ptr with __rcu @__next triggering the following sparse warning. net/core/dev.c:4331:17: error: incompatible types in comparison expression (different address spaces) * It doesn't perform rcu_dereference*() and computes the entry address using container_of() directly from the __rcu pointer which is inconsitent with other rculist interface. As a result, all three in-kernel users - net/core/dev.c, macvlan, cgroup - are buggy. They dereference the pointer w/o going through read barrier. * While ->next dereference passes through list_next_rcu(), the compiler is still free to fetch ->next more than once and thus nullify the "__ptr != __next" condition check. Fix it by making list_first_or_null_rcu() dereference ->next directly using ACCESS_ONCE() and then use list_entry_rcu() on it like other rculist accessors. v2: Paul pointed out that the compiler may fetch the pointer more than once nullifying the condition check. ACCESS_ONCE() added on ->next dereference. v3: Restored () around macro param which was accidentally removed. Spotted by Paul. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Li Zefan <lizefan@huawei.com> Cc: Patrick McHardy <kaber@trash.net> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2013-09-26 17:18:13 -07:00
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acpi	ACPI: Try harder to resolve _ADR collisions for bridges	2013-08-29 09:47:29 -07:00
asm-generic	Fix TLB gather virtual address range invalidation corner cases	2013-08-20 08:43:05 -07:00
clocksource	ARM: late Exynos multiplatform changes	2013-05-07 11:28:42 -07:00
crypto
drm	Merge branch 'drm-radeon-sun-hainan' of git://people.freedesktop.org/~airlied/linux	2013-05-21 08:50:57 -07:00
dt-bindings
keys
linux	rculist: list_first_or_null_rcu() should use list_entry_rcu()	2013-09-26 17:18:13 -07:00
math-emu
media	Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media	2013-06-18 06:25:08 -10:00
memory
misc
net	net_sched: restore "linklayer atm" handling	2013-09-14 06:54:55 -07:00
pcmcia
ras
rdma
rxrpc
scsi	Merge branch 'postmerge' into for-linus	2013-05-10 07:54:01 -07:00
sound	ASoC: dapm: Treat DAI widgets like AIF widgets for power	2013-06-07 15:54:50 +01:00
target	iscsi-target: Fix iscsit_sequence_cmd reject handling for iser	2013-08-04 16:51:17 +08:00
trace	Fixed regressions (two stability regressions and a performance	2013-05-14 09:30:54 -07:00
uapi	ICMPv6: treat dest unreachable codes 5 and 6 as EACCES, not EPROTO	2013-09-14 06:54:56 -07:00
video	Merge branch 'fbdev-3.10-fixes' of git://gitorious.org/linux-omap-dss2/linux into linux-fbdev/for-3.10-fixes	2013-05-29 17:00:34 +08:00
xen	xenbus: delay xenbus frontend resume if xenstored is not running	2013-05-29 09:04:19 -04:00
Kbuild