mwifiex: initiate card-specific work atomically

The non-atomic test + set is a little awkward here, and it technically
means we might double-schedule work unnecessarily. AFAICT, this is not
really a problem, since the extra "work" will be a no-op (the flag(s)
will be cleared by then), but it's still an anti-pattern.

Rewrite this to use the atomic test_and_set_bit() helper instead.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c
index ac62bce..5f56e8e 100644
--- a/drivers/net/wireless/marvell/mwifiex/pcie.c
+++ b/drivers/net/wireless/marvell/mwifiex/pcie.c
@@ -2837,12 +2837,9 @@ static void mwifiex_pcie_device_dump(struct mwifiex_adapter *adapter)
 {
 	struct pcie_service_card *card = adapter->card;
 
-	if (test_bit(MWIFIEX_IFACE_WORK_DEVICE_DUMP, &card->work_flags))
-		return;
-
-	set_bit(MWIFIEX_IFACE_WORK_DEVICE_DUMP, &card->work_flags);
-
-	schedule_work(&card->work);
+	if (!test_and_set_bit(MWIFIEX_IFACE_WORK_DEVICE_DUMP,
+			      &card->work_flags))
+		schedule_work(&card->work);
 }
 
 static void mwifiex_pcie_free_buffers(struct mwifiex_adapter *adapter)