fs/writeback, rcu: Don't use list_entry_rcu() for pointer offsetting in bdi_split_wor...
authorTejun Heo <tj@kernel.org>
Tue, 27 Oct 2015 05:19:39 +0000 (14:19 +0900)
committerIngo Molnar <mingo@kernel.org>
Wed, 28 Oct 2015 12:17:30 +0000 (13:17 +0100)
commitb33e18f61bd18227a456016a77b1a968f5bc1d65
tree864f100a805ea16e59bad2fc003f747db27f94c1
parente4340bbb07dd38339c0773543dd928886e512a57
fs/writeback, rcu: Don't use list_entry_rcu() for pointer offsetting in bdi_split_work_to_wbs()

bdi_split_work_to_wbs() uses list_for_each_entry_rcu_continue()
to walk @bdi->wb_list.  To set up the initial iteration
condition, it uses list_entry_rcu() to calculate the entry
pointer corresponding to the list head; however, this isn't an
actual RCU dereference and using list_entry_rcu() for it ended
up breaking a proposed list_entry_rcu() change because it was
feeding an non-lvalue pointer into the macro.

Don't use the RCU variant for simple pointer offsetting.  Use
list_entry() instead.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Patrick Marlier <patrick.marlier@gmail.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pranith kumar <bobby.prani@gmail.com>
Link: http://lkml.kernel.org/r/20151027051939.GA19355@mtj.duckdns.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
fs/fs-writeback.c