From: Brian Norris Date: Fri, 13 Jan 2017 23:35:38 +0000 (-0800) Subject: mwifiex: pcie: read FROMDEVICE DMA-able memory with READ_ONCE() X-Git-Tag: v4.14-rc1~1463^2~264^2~37 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=fe116788393942eef11d5c0f1cb16b1ef423970d;p=platform%2Fkernel%2Flinux-rpi3.git mwifiex: pcie: read FROMDEVICE DMA-able memory with READ_ONCE() In mwifiex_delay_for_sleep_cookie(), we're looping and waiting for the PCIe endpoint to write a magic value back to memory, to signal that it has finished going to sleep. We're not letting the compiler know that this might change underneath our feet though. Let's do that, for good hygiene. I'm not aware of this fixing any concrete problems. I also give no guarantee that this loop is actually correct in any other way, but at least this looks like an improvement to me. Signed-off-by: Brian Norris Signed-off-by: Kalle Valo --- diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c index b8a07d3..ca51411 100644 --- a/drivers/net/wireless/marvell/mwifiex/pcie.c +++ b/drivers/net/wireless/marvell/mwifiex/pcie.c @@ -442,7 +442,7 @@ static void mwifiex_delay_for_sleep_cookie(struct mwifiex_adapter *adapter, for (count = 0; count < max_delay_loop_cnt; count++) { buffer = card->cmdrsp_buf->data - INTF_HEADER_LEN; - sleep_cookie = *(u32 *)buffer; + sleep_cookie = READ_ONCE(*(u32 *)buffer); if (sleep_cookie == MWIFIEX_DEF_SLEEP_COOKIE) { mwifiex_dbg(adapter, INFO,