blktap: fix race memory refernce with ring_ok. fix race memory refernce with ring_ok. Signed-off-by: Isaku Yamahata diff --git a/drivers/xen/blktap/blktap.c b/drivers/xen/blktap/blktap.c --- a/drivers/xen/blktap/blktap.c +++ b/drivers/xen/blktap/blktap.c @@ -617,6 +617,9 @@ static int blktap_release(struct inode * if (!info) return 0; + info->ring_ok = 0; + smp_wmb(); + info->dev_inuse = 0; DPRINTK("Freeing device [/dev/xen/blktap%d]\n",info->minor); @@ -717,6 +720,7 @@ static int blktap_mmap(struct file *filp #endif info->vma = vma; + smp_wmb(); info->ring_ok = 1; return 0; fail: @@ -1390,6 +1394,7 @@ static void dispatch_rw_block_io(blkif_t WPRINTK("blktap: ring not ready for requests!\n"); goto fail_response; } + smp_rmb(); if (RING_FULL(&info->ufe_ring)) { WPRINTK("blktap: fe_ring is full, can't add "