[PATCH v2 3/3] mwifiex: pcie: read FROMDEVICE DMA-able memory with READ_ONCE()

From	Brian Norris <briannorris@chromium.org>
Newsgroups	linux.kernel
Subject	[PATCH v2 3/3] mwifiex: pcie: read FROMDEVICE DMA-able memory with READ_ONCE()
Date	2017-01-14 00:40 +0100
Message-ID	<sZjBU-74g-11@gated-at.bofh.it> (permalink)
References	<sZjBU-74g-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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 <briannorris@chromium.org>
---
v2: new in v2
---
 drivers/net/wireless/marvell/mwifiex/pcie.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c
index 194e0e04c3b1..c2511f212502 100644
--- a/drivers/net/wireless/marvell/mwifiex/pcie.c
+++ b/drivers/net/wireless/marvell/mwifiex/pcie.c
@@ -440,7 +440,7 @@ 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,
-- 
2.11.0.483.g087da7b7c-goog

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[PATCH v2 3/3] mwifiex: pcie: read FROMDEVICE DMA-able memory with READ_ONCE() Brian Norris <briannorris@chromium.org> - 2017-01-14 00:40 +0100

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