linux-kernel - [PATCH] cxl/mem: Fix an error code in cxl_mem_mbox

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Date:   Tue, 16 Feb 2021 22:16:48 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Alison Schofield <alison.schofield@...el.com>,
        Ben Widawsky <ben.widawsky@...el.com>
Cc:     Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: [PATCH] cxl/mem: Fix an error code in cxl_mem_mbox_get()

Smatch complains that sometimes when we return success we are holding
the mutex and sometimes we have released the mutex.  It turns out that
the bug is a missing error code if the mbox is not ready.  It should
return -EBUSY instead of success.

Fixes: cc1967ac93ab ("cxl/mem: Find device capabilities")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
 drivers/cxl/mem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 3bca8451348a..2ebc84e4d202 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -383,8 +383,8 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 static int cxl_mem_mbox_get(struct cxl_mem *cxlm)
 {
 	struct device *dev = &cxlm->pdev->dev;
-	int rc = -EBUSY;
 	u64 md_status;
+	int rc;
 
 	mutex_lock_io(&cxlm->mbox_mutex);
 
@@ -414,6 +414,7 @@ static int cxl_mem_mbox_get(struct cxl_mem *cxlm)
 	md_status = readq(cxlm->memdev_regs + CXLMDEV_STATUS_OFFSET);
 	if (!(md_status & CXLMDEV_MBOX_IF_READY && CXLMDEV_READY(md_status))) {
 		dev_err(dev, "mbox: reported doorbell ready, but not mbox ready\n");
+		rc = -EBUSY;
 		goto out;
 	}
 
-- 
2.30.0