On Wed, Oct 28, 2015 at 09:35:42PM +0100, Patrick Marlier wrote: > > > On 10/28/2015 09:33 AM, Ingo Molnar wrote: > > > >* Tejun Heo <[email protected]> wrote: > > > >>Subject: writeback: 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. > >> > >>Signed-off-by: Tejun Heo <[email protected]> > >>--- > >> fs/fs-writeback.c | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >>diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > >>index 29e4599..7378169 100644 > >>--- a/fs/fs-writeback.c > >>+++ b/fs/fs-writeback.c > >>@@ -779,8 +779,8 @@ static void bdi_split_work_to_wbs(struct > >>backing_dev_info *bdi, > >> bool skip_if_busy) > >> { > >> struct bdi_writeback *last_wb = NULL; > >>- struct bdi_writeback *wb = list_entry_rcu(&bdi->wb_list, > >>- struct bdi_writeback, bdi_node); > >>+ struct bdi_writeback *wb = list_entry(&bdi->wb_list, > >>+ struct bdi_writeback, bdi_node); > >> > >> might_sleep(); > > > >Any objections against me applying this fix to tip:core/rcu so that I can > >push the > >recent RCU changes towards linux-next without triggering a build failure? > > No objection on my side but probably you are waiting for an ack from > somebody else.
I am guessing that he was asking Tejun, but just for the record, I am OK with it as well: Acked-by: Paul E. McKenney <[email protected]> Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
