Thanks! Sure, I'll resent it as bugfix in v2. > -----Original Message----- > From: Vadim Pasternak <vadimp@xxxxxxxxxx> > Sent: Friday, May 7, 2021 11:39 AM > To: Liming Sun <limings@xxxxxxxxxx>; Andy Shevchenko > <andy@xxxxxxxxxxxxx>; Darren Hart <dvhart@xxxxxxxxxxxxx> > Cc: linux-kernel@xxxxxxxxxxxxxxx; platform-driver-x86@xxxxxxxxxxxxxxx > Subject: RE: [PATCH v1 1/1] platform/mellanox: mlxbf-tmfifo: Fix a memory > barrier issue > > > > > -----Original Message----- > > From: Liming Sun <limings@xxxxxxxxxx> > > Sent: Friday, May 7, 2021 6:19 PM > > To: Andy Shevchenko <andy@xxxxxxxxxxxxx>; Darren Hart > > <dvhart@xxxxxxxxxxxxx>; Vadim Pasternak <vadimp@xxxxxxxxxx> > > Cc: Liming Sun <limings@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; > > platform-driver-x86@xxxxxxxxxxxxxxx > > Subject: [PATCH v1 1/1] platform/mellanox: mlxbf-tmfifo: Fix a memory > > barrier issue > > > > The virtio framework uses wmb() when updating avail->idx. It guarantees > > the write order, but not necessarily loading order for the code accessing > the > > memory. This commit adds a load barrier after reading the avail->idx to > make > > sure all the data in the descriptor is visible. It also adds a barrier when > > returning the packet to virtio framework to make sure read/writes are > visible > > to the virtio code. > > I suppose it should be sent as Bugfix? > > > > > Signed-off-by: Liming Sun <limings@xxxxxxxxxx> > > --- > > drivers/platform/mellanox/mlxbf-tmfifo.c | 11 ++++++++++- > > 1 file changed, 10 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c > > b/drivers/platform/mellanox/mlxbf-tmfifo.c > > index bbc4e71..38800e8 100644 > > --- a/drivers/platform/mellanox/mlxbf-tmfifo.c > > +++ b/drivers/platform/mellanox/mlxbf-tmfifo.c > > @@ -294,6 +294,9 @@ static irqreturn_t mlxbf_tmfifo_irq_handler(int irq, > > void *arg) > > if (vring->next_avail == virtio16_to_cpu(vdev, vr->avail->idx)) > > return NULL; > > > > + /* Make sure 'avail->idx' is visible already. */ > > + virtio_rmb(false); > > + > > idx = vring->next_avail % vr->num; > > head = virtio16_to_cpu(vdev, vr->avail->ring[idx]); > > if (WARN_ON(head >= vr->num)) > > @@ -322,7 +325,7 @@ static void mlxbf_tmfifo_release_desc(struct > > mlxbf_tmfifo_vring *vring, > > * done or not. Add a memory barrier here to make sure the update > > above > > * completes before updating the idx. > > */ > > - mb(); > > + virtio_mb(false); > > vr->used->idx = cpu_to_virtio16(vdev, vr_idx + 1); } > > > > @@ -733,6 +736,12 @@ static bool mlxbf_tmfifo_rxtx_one_desc(struct > > mlxbf_tmfifo_vring *vring, > > desc = NULL; > > fifo->vring[is_rx] = NULL; > > > > + /* > > + * Make sure the load/store are in order before > > + * returning back to virtio. > > + */ > > + virtio_mb(false); > > + > > /* Notify upper layer that packet is done. */ > > spin_lock_irqsave(&fifo->spin_lock[is_rx], flags); > > vring_interrupt(0, vring->vq); > > -- > > 1.8.3.1
