2021-02-16 19:19:49

by Dan Carpenter

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 <[email protected]>
---
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

2021-02-16 20:58:11

by Dan Williams

Subject: Re: [PATCH] cxl/mem: Fix an error code in cxl_mem_mbox_get()

On Tue, Feb 16, 2021 at 11:17 AM Dan Carpenter <[email protected]> wrote:
>
> 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 <[email protected]>
> ---
> 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;

Hey, Smatch gave a more thorough report than Coverity:

http://lore.kernel.org/r/[email protected]