Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Chris Lew <clew@codeaurora.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>
Subject: [PATCH 5.4 21/80] rpmsg: glink: Set tail pointer to 0 at end of FIFO
Date:   Thu, 19 Dec 2019 19:34:13 +0100
Message-Id: <20191219183101.268904080@linuxfoundation.org>
In-Reply-To: <20191219183031.278083125@linuxfoundation.org>
References: <20191219183031.278083125@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Chris Lew <clew@codeaurora.org>

commit 4623e8bf1de0b86e23a56cdb39a72f054e89c3bd upstream.

When wrapping around the FIFO, the remote expects the tail pointer to
be reset to 0 on the edge case where the tail equals the FIFO length.

Fixes: caf989c350e8 ("rpmsg: glink: Introduce glink smem based transport")
Cc: stable@vger.kernel.org
Signed-off-by: Chris Lew <clew@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/rpmsg/qcom_glink_smem.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/rpmsg/qcom_glink_smem.c
+++ b/drivers/rpmsg/qcom_glink_smem.c
@@ -105,7 +105,7 @@ static void glink_smem_rx_advance(struct
 	tail = le32_to_cpu(*pipe->tail);
 
 	tail += count;
-	if (tail > pipe->native.length)
+	if (tail >= pipe->native.length)
 		tail -= pipe->native.length;
 
 	*pipe->tail = cpu_to_le32(tail);