> On 21 Jun 2018, at 00.54, Heiner Litz <hlitz@xxxxxxxx> wrote: > > READ_ONCE does not imply a read memory barrier in the presence of control > dependencies between two separate memory locations (flags and data). On x86 > TSO, reading from the data page might be reordered before the flags read. > See chapter CONTROL DEPENDENCIES in > https://www.kernel.org/doc/Documentation/memory-barriers.txt > > Signed-off-by: Heiner Litz <hlitz@xxxxxxxx> > --- > drivers/lightnvm/pblk-rb.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c > index a81a97e..5f09983 100644 > --- a/drivers/lightnvm/pblk-rb.c > +++ b/drivers/lightnvm/pblk-rb.c > @@ -545,6 +545,9 @@ unsigned int pblk_rb_read_to_bio(struct pblk_rb *rb, struct nvm_rq *rqd, > goto try; > } > > + /* Observe control dependency between flags and data read */ > + smp_rmb(); > + > page = virt_to_page(entry->data); > if (!page) { > pr_err("pblk: could not allocate write bio page\n"); > -- > 2.7.4 Thanks for sending the patch; I was wondering where it went. Reviewed-by: Javier González <javier@xxxxxxxxxxxx>
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