netdev - [PATCH wireless-drivers-next 4/4] net: wlcore: fix read pointer update

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Message-Id: <E1lolvi-0003Ri-39@rmk-PC.armlinux.org.uk>
Date:   Thu, 03 Jun 2021 12:54:30 +0100
From:   Russell King <rmk+kernel@...linux.org.uk>
To:     Kalle Valo <kvalo@...eaurora.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH wireless-drivers-next 4/4] net: wlcore: fix read pointer
 update

When reading the fw_log structure from the device's memory, we could
race with the firmware updating the actual_buff_size and buff_write_ptr
members of this structure. This would lead to bytes being dropped from
the log.

Fix this by writing back the actual - now fixed - clear_ptr which
reflects where we read up to in the buffer.

This also means that we must not check that the clear_ptr matches the
current write pointer, so remove that check.

Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
---
 drivers/net/wireless/ti/wlcore/event.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/ti/wlcore/event.c b/drivers/net/wireless/ti/wlcore/event.c
index 8a67a708c96e..46ab69eab26a 100644
--- a/drivers/net/wireless/ti/wlcore/event.c
+++ b/drivers/net/wireless/ti/wlcore/event.c
@@ -96,15 +96,9 @@ int wlcore_event_fw_logger(struct wl1271 *wl)
 		clear_ptr = addr_ptr + WL18XX_LOGGER_BUFF_OFFSET + len;
 	}
 
-	/* double check that clear address and write pointer are the same */
-	if (clear_ptr != le32_to_cpu(fw_log.buff_write_ptr)) {
-		wl1271_error("Calculate of clear addr Clear = %x, write = %x",
-			     clear_ptr, le32_to_cpu(fw_log.buff_write_ptr));
-	}
-
-	/* indicate FW about Clear buffer */
+	/* Update the read pointer */
 	ret = wlcore_write32(wl, addr + WL18XX_LOGGER_READ_POINT_OFFSET,
-			     fw_log.buff_write_ptr);
+			     clear_ptr);
 free_out:
 	kfree(buffer);
 out:
-- 
2.20.1