[PATCH] nvme: target: fix error checking in nvmet_fc_schedule_delete_assoc()

[PATCH] nvme: target: fix error checking in nvmet_fc_schedule_delete_assoc()

[Alexandr Sapozhnkiov]

From: Alexandr Sapozhnikov <alsp705@gmail.com>

The nvmet_fc_tgtport_get() function may return an error.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Alexandr Sapozhnikov <alsp705@gmail.com>
---
 drivers/nvme/target/fc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index 337ee1cb09ae..68a416a92bfc 100644
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -1110,8 +1110,8 @@ nvmet_fc_delete_assoc_work(struct work_struct *work)
 static void
 nvmet_fc_schedule_delete_assoc(struct nvmet_fc_tgt_assoc *assoc)
 {
-	nvmet_fc_tgtport_get(assoc->tgtport);
-	queue_work(nvmet_wq, &assoc->del_work);
+	if (nvmet_fc_tgtport_get(assoc->tgtport))
+		queue_work(nvmet_wq, &assoc->del_work);
 }
 
 static bool
-- 
2.43.0

Re: [PATCH] nvme: target: fix error checking in nvmet_fc_schedule_delete_assoc()

[Christoph Hellwig]

Adding Daniel who has been touching this area recently.

On Thu, Oct 02, 2025 at 12:22:01PM +0300, Alexandr Sapozhnkiov wrote:
> From: Alexandr Sapozhnikov <alsp705@gmail.com>
> 
> The nvmet_fc_tgtport_get() function may return an error.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Signed-off-by: Alexandr Sapozhnikov <alsp705@gmail.com>
> ---
>  drivers/nvme/target/fc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
> index 337ee1cb09ae..68a416a92bfc 100644
> --- a/drivers/nvme/target/fc.c
> +++ b/drivers/nvme/target/fc.c
> @@ -1110,8 +1110,8 @@ nvmet_fc_delete_assoc_work(struct work_struct *work)
>  static void
>  nvmet_fc_schedule_delete_assoc(struct nvmet_fc_tgt_assoc *assoc)
>  {
> -	nvmet_fc_tgtport_get(assoc->tgtport);
> -	queue_work(nvmet_wq, &assoc->del_work);
> +	if (nvmet_fc_tgtport_get(assoc->tgtport))
> +		queue_work(nvmet_wq, &assoc->del_work);
>  }
>  
>  static bool
> -- 
> 2.43.0
---end quoted text---

Re: [PATCH] nvme: target: fix error checking in nvmet_fc_schedule_delete_assoc()

[Daniel Wagner]

Hi Alexandr,

On Fri, Oct 03, 2025 at 12:13:54PM +0200, Christoph Hellwig wrote:
> Adding Daniel who has been touching this area recently.
> 
> On Thu, Oct 02, 2025 at 12:22:01PM +0300, Alexandr Sapozhnkiov wrote:
> > From: Alexandr Sapozhnikov <alsp705@gmail.com>
> > 
> > The nvmet_fc_tgtport_get() function may return an error.

This description is not correct, because nvmet_fc_tgtport_get wraps
around kref_get_unless_zero. The return value is never an error code.

> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> > 
> > Signed-off-by: Alexandr Sapozhnikov <alsp705@gmail.com>
> > ---
> >  drivers/nvme/target/fc.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
> > index 337ee1cb09ae..68a416a92bfc 100644
> > --- a/drivers/nvme/target/fc.c
> > +++ b/drivers/nvme/target/fc.c
> > @@ -1110,8 +1110,8 @@ nvmet_fc_delete_assoc_work(struct work_struct *work)
> >  static void
> >  nvmet_fc_schedule_delete_assoc(struct nvmet_fc_tgt_assoc *assoc)
> >  {
> > -	nvmet_fc_tgtport_get(assoc->tgtport);
> > -	queue_work(nvmet_wq, &assoc->del_work);
> > +	if (nvmet_fc_tgtport_get(assoc->tgtport))
> > +		queue_work(nvmet_wq, &assoc->del_work);

nvmet_fc_schedule_delete_assoc can only be called when a reference is
held on the assoc->tgtport. The nvmet_fc_tgtport_get is necessary so
that the resource is not going away while the work item is executed.

And this patch doesn't seem against a recent kernel as it misses commit
70289ae5cac4 ("nvmet-fc: put ref when assoc->del_work is already
scheduled") which was added for 6.15.

I am not against this change but I was under the impression we don't add
code to make some tools happy. Maybe it would be enough to add a
comment?

Thanks,
Daniel

Re: [PATCH] nvme: target: fix error checking in nvmet_fc_schedule_delete_assoc()

[Markus Elfring]

> The nvmet_fc_tgtport_get() function may return an error.

Would a corresponding imperative wording become helpful for an improved change description?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.17#n94

Regards,
Markus