Re: [PATCH 5.10 048/103] s390/qeth: fix deadlock during failing recovery

[Naresh Kamboju]

Following commit caused the build failures on s390,

On Mon, 27 Sept 2021 at 22:43, Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Alexandra Winter <wintera@xxxxxxxxxxxxx>
>
> [ Upstream commit d2b59bd4b06d84a4eadb520b0f71c62fe8ec0a62 ]
>
> Commit 0b9902c1fcc5 ("s390/qeth: fix deadlock during recovery") removed
> taking discipline_mutex inside qeth_do_reset(), fixing potential
> deadlocks. An error path was missed though, that still takes
> discipline_mutex and thus has the original deadlock potential.
>
> Intermittent deadlocks were seen when a qeth channel path is configured
> offline, causing a race between qeth_do_reset and ccwgroup_remove.
> Call qeth_set_offline() directly in the qeth_do_reset() error case and
> then a new variant of ccwgroup_set_offline(), without taking
> discipline_mutex.
>
> Fixes: b41b554c1ee7 ("s390/qeth: fix locking for discipline setup / removal")
> Signed-off-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
> Reviewed-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
> Signed-off-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  arch/s390/include/asm/ccwgroup.h  |  2 +-
>  drivers/s390/cio/ccwgroup.c       | 10 ++++++++--
>  drivers/s390/net/qeth_core_main.c |  3 ++-
>  3 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/arch/s390/include/asm/ccwgroup.h b/arch/s390/include/asm/ccwgroup.h
> index ad3acb1e882b..8a22da9a735a 100644
> --- a/arch/s390/include/asm/ccwgroup.h
> +++ b/arch/s390/include/asm/ccwgroup.h
> @@ -58,7 +58,7 @@ struct ccwgroup_device *get_ccwgroupdev_by_busid(struct ccwgroup_driver *gdrv,
>                                                  char *bus_id);
>
>  extern int ccwgroup_set_online(struct ccwgroup_device *gdev);
> -extern int ccwgroup_set_offline(struct ccwgroup_device *gdev);
> +int ccwgroup_set_offline(struct ccwgroup_device *gdev, bool call_gdrv);
>
>  extern int ccwgroup_probe_ccwdev(struct ccw_device *cdev);
>  extern void ccwgroup_remove_ccwdev(struct ccw_device *cdev);
> diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
> index 483a9ecfcbb1..cfdc1c7825d0 100644
> --- a/drivers/s390/cio/ccwgroup.c
> +++ b/drivers/s390/cio/ccwgroup.c
> @@ -98,12 +98,13 @@ EXPORT_SYMBOL(ccwgroup_set_online);
>  /**
>   * ccwgroup_set_offline() - disable a ccwgroup device
>   * @gdev: target ccwgroup device
> + * @call_gdrv: Call the registered gdrv set_offline function
>   *
>   * This function attempts to put the ccwgroup device into the offline state.
>   * Returns:
>   *  %0 on success and a negative error value on failure.
>   */
> -int ccwgroup_set_offline(struct ccwgroup_device *gdev)
> +int ccwgroup_set_offline(struct ccwgroup_device *gdev, bool call_gdrv)
>  {
>         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
>         int ret = -EINVAL;
> @@ -112,11 +113,16 @@ int ccwgroup_set_offline(struct ccwgroup_device *gdev)
>                 return -EAGAIN;
>         if (gdev->state == CCWGROUP_OFFLINE)
>                 goto out;
> +       if (!call_gdrv) {
> +               ret = 0;
> +               goto offline;
> +       }
>         if (gdrv->set_offline)
>                 ret = gdrv->set_offline(gdev);
>         if (ret)
>                 goto out;
>
> +offline:
>         gdev->state = CCWGROUP_OFFLINE;
>  out:
>         atomic_set(&gdev->onoff, 0);
> @@ -145,7 +151,7 @@ static ssize_t ccwgroup_online_store(struct device *dev,
>         if (value == 1)
>                 ret = ccwgroup_set_online(gdev);
>         else if (value == 0)
> -               ret = ccwgroup_set_offline(gdev);
> +               ret = ccwgroup_set_offline(gdev, true);
>         else
>                 ret = -EINVAL;
>  out:
> diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
> index 7b0155b0e99e..15477bfb5bd8 100644
> --- a/drivers/s390/net/qeth_core_main.c
> +++ b/drivers/s390/net/qeth_core_main.c
> @@ -5406,7 +5406,8 @@ static int qeth_do_reset(void *data)
>                 dev_info(&card->gdev->dev,
>                          "Device successfully recovered!\n");
>         } else {
> -               ccwgroup_set_offline(card->gdev);
> +               qeth_set_offline(card, disc, true);
> +               ccwgroup_set_offline(card->gdev, false);

drivers/s390/net/qeth_core_main.c: In function 'qeth_close_dev_handler':
drivers/s390/net/qeth_core_main.c:83:9: error: too few arguments to
function 'ccwgroup_set_offline'
   83 |         ccwgroup_set_offline(card->gdev);
      |         ^~~~~~~~~~~~~~~~~~~~
In file included from drivers/s390/net/qeth_core.h:44,
                 from drivers/s390/net/qeth_core_main.c:46:
arch/s390/include/asm/ccwgroup.h:61:5: note: declared here
   61 | int ccwgroup_set_offline(struct ccwgroup_device *gdev, bool call_gdrv);
      |     ^~~~~~~~~~~~~~~~~~~~
make[3]: *** [scripts/Makefile.build:280:
drivers/s390/net/qeth_core_main.o] Error 1

Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx>


Build url:
https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc/-/jobs/1626658768#L73


--
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