From: Drake Talley <drake@xxxxxxxxxxxxxxx> codestyle change that fixes the following report from checkpatch: > WARNING: memory barrier without comment > #2101: FILE: drivers/staging/qlge/qlge_main.c:2101: The added comment identifies the next item from the circular buffer (rx_ring->curr_entry) and its handling/unmapping as the two operations that must not be reordered. Based on the kernel documentation for memory barriers in circular buffers (https://www.kernel.org/doc/Documentation/circular-buffers.txt) and the presence of atomic operations in the current context I'm assuming this usage of the memory barrier is akin to what is explained in the linked doc. There are a couple of other uncommented usages of memory barriers in the current file. If this comment is adequate I can add similar comments to the others. Signed-off-by: Drake Talley <drake@xxxxxxxxxxxxxxx> --- drivers/staging/qlge/qlge_main.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/staging/qlge/qlge_main.c b/drivers/staging/qlge/qlge_main.c index c8403dbb5bad..f70390bce6d8 100644 --- a/drivers/staging/qlge/qlge_main.c +++ b/drivers/staging/qlge/qlge_main.c @@ -2098,6 +2098,12 @@ static int qlge_clean_outbound_rx_ring(struct rx_ring *rx_ring) rx_ring->cq_id, prod, rx_ring->cnsmr_idx); net_rsp = (struct qlge_ob_mac_iocb_rsp *)rx_ring->curr_entry; + /* + * Ensure that the next item from the ring buffer is loaded + * before being processed. + * Adding rmb() prevents the compiler from reordering the read + * and subsequent handling of the outbound completion pointer. + */ rmb(); switch (net_rsp->opcode) { case OPCODE_OB_MAC_TSO_IOCB: -- 2.34.1
