[PATCH v2 0/2] Call scsi_host_busy() after the SCSI host has been added

[PATCH v2 0/2] Call scsi_host_busy() after the SCSI host has been added

[Bart Van Assche]

Hi Martin,

The UFS driver is the only SCSI driver I know of that may call
scsi_host_busy() before the SCSI host has been added. This patch series
modifies the UFS driver such that scsi_host_busy() is only called after the
SCSI host has been added. Additionally, commit a0b7780602b1 ("scsi: core:
Fix a regression triggered by scsi_host_busy()") is reverted because all
scsi_host_busy() calls now happen after the corresponding SCSI host has
been added.

Please consider this patch series for the next merge window.

Thanks,

Bart.

Changes compared to v1:
 - Removed the WARN_ON_ONCE(!shost->tag_set.ops); statement from patch 2/2.

Bart Van Assche (2):
  ufs: core: Only call scsi_host_busy() after the SCSI host has been
    added
  scsi: core: Revert "Fix a regression triggered by scsi_host_busy()"

 drivers/scsi/hosts.c      | 5 ++---
 drivers/ufs/core/ufshcd.c | 6 ++++--
 2 files changed, 6 insertions(+), 5 deletions(-)

[PATCH v2 1/2] ufs: core: Only call scsi_host_busy() after the SCSI host has been added

[Bart Van Assche]

scsi_host_busy() iterates over the host tag set. The host tag set is
initialized by scsi_mq_setup_tags(). The latter function is called by
scsi_add_host(). Hence only call scsi_host_busy() after the SCSI host
has been added. This patch prepares for reverting commit a0b7780602b1
("scsi: core: Fix a regression triggered by scsi_host_busy()").

Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufshcd.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 562d8cffc6f6..69630677b23f 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -283,7 +283,8 @@ static bool ufshcd_has_pending_tasks(struct ufs_hba *hba)
 
 static bool ufshcd_is_ufs_dev_busy(struct ufs_hba *hba)
 {
-	return scsi_host_busy(hba->host) || ufshcd_has_pending_tasks(hba);
+	return (hba->scsi_host_added && scsi_host_busy(hba->host)) ||
+		ufshcd_has_pending_tasks(hba);
 }
 
 static const struct ufs_dev_quirk ufs_fixups[] = {
@@ -678,7 +679,8 @@ static void ufshcd_print_host_state(struct ufs_hba *hba)
 
 	dev_err(hba->dev, "UFS Host state=%d\n", hba->ufshcd_state);
 	dev_err(hba->dev, "%d outstanding reqs, tasks=0x%lx\n",
-		scsi_host_busy(hba->host), hba->outstanding_tasks);
+		hba->scsi_host_added ? scsi_host_busy(hba->host) : 0,
+		hba->outstanding_tasks);
 	dev_err(hba->dev, "saved_err=0x%x, saved_uic_err=0x%x\n",
 		hba->saved_err, hba->saved_uic_err);
 	dev_err(hba->dev, "Device power mode=%d, UIC link state=%d\n",

[PATCH v2 2/2] scsi: core: Revert "Fix a regression triggered by scsi_host_busy()"

[Bart Van Assche]

Revert commit a0b7780602b1 ("scsi: core: Fix a regression triggered by
scsi_host_busy()") because all scsi_host_busy() calls now happen after
the corresponding SCSI host has been added.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/hosts.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 196479cbfe6e..4d17f242d191 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -626,9 +626,8 @@ int scsi_host_busy(struct Scsi_Host *shost)
 {
 	int cnt = 0;
 
-	if (shost->tag_set.ops)
-		blk_mq_tagset_busy_iter(&shost->tag_set,
-					scsi_host_check_in_flight, &cnt);
+	blk_mq_tagset_busy_iter(&shost->tag_set,
+				scsi_host_check_in_flight, &cnt);
 	return cnt;
 }
 EXPORT_SYMBOL(scsi_host_busy);

Re: [PATCH v2 2/2] scsi: core: Revert "Fix a regression triggered by scsi_host_busy()"

[John Garry]

On 09/01/2026 20:51, Bart Van Assche wrote:
> Revert commit a0b7780602b1 ("scsi: core: Fix a regression triggered by
> scsi_host_busy()") because all scsi_host_busy() calls now happen after
> the corresponding SCSI host has been added.
> 
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>

thanks

Reviewed-by: John Garry <john.g.garry@oracle.com>


> ---
>   drivers/scsi/hosts.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index 196479cbfe6e..4d17f242d191 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -626,9 +626,8 @@ int scsi_host_busy(struct Scsi_Host *shost)
>   {
>   	int cnt = 0;
>   
> -	if (shost->tag_set.ops)
> -		blk_mq_tagset_busy_iter(&shost->tag_set,
> -					scsi_host_check_in_flight, &cnt);
> +	blk_mq_tagset_busy_iter(&shost->tag_set,
> +				scsi_host_check_in_flight, &cnt);
>   	return cnt;
>   }
>   EXPORT_SYMBOL(scsi_host_busy);
> 

Re: [PATCH v2 0/2] Call scsi_host_busy() after the SCSI host has been added

[Martin K. Petersen]

Bart,

> The UFS driver is the only SCSI driver I know of that may call
> scsi_host_busy() before the SCSI host has been added. This patch
> series modifies the UFS driver such that scsi_host_busy() is only
> called after the SCSI host has been added. Additionally, commit
> a0b7780602b1 ("scsi: core: Fix a regression triggered by
> scsi_host_busy()") is reverted because all scsi_host_busy() calls now
> happen after the corresponding SCSI host has been added.

Applied to 6.20/scsi-staging, thanks!

-- 
Martin K. Petersen

Re: [PATCH v2 1/2] ufs: core: Only call scsi_host_busy() after the SCSI host has been added

[Peter Wang (王信友)]

On Fri, 2026-01-09 at 12:51 -0800, Bart Van Assche wrote:
> scsi_host_busy() iterates over the host tag set. The host tag set is
> initialized by scsi_mq_setup_tags(). The latter function is called by
> scsi_add_host(). Hence only call scsi_host_busy() after the SCSI host
> has been added. This patch prepares for reverting commit a0b7780602b1
> ("scsi: core: Fix a regression triggered by scsi_host_busy()").
> 
> Reviewed-by: John Garry <john.g.garry@oracle.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/ufs/core/ufshcd.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 562d8cffc6f6..69630677b23f 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -283,7 +283,8 @@ static bool ufshcd_has_pending_tasks(struct
> ufs_hba *hba)
> 
>  static bool ufshcd_is_ufs_dev_busy(struct ufs_hba *hba)
>  {
> -       return scsi_host_busy(hba->host) ||
> ufshcd_has_pending_tasks(hba);
> +       return (hba->scsi_host_added && scsi_host_busy(hba->host)) ||
> +               ufshcd_has_pending_tasks(hba);
>  }
> 
>  static const struct ufs_dev_quirk ufs_fixups[] = {
> @@ -678,7 +679,8 @@ static void ufshcd_print_host_state(struct
> ufs_hba *hba)
> 
>         dev_err(hba->dev, "UFS Host state=%d\n", hba->ufshcd_state);
>         dev_err(hba->dev, "%d outstanding reqs, tasks=0x%lx\n",
> -               scsi_host_busy(hba->host), hba->outstanding_tasks);
> +               hba->scsi_host_added ? scsi_host_busy(hba->host) : 0,
> +               hba->outstanding_tasks);
>         dev_err(hba->dev, "saved_err=0x%x, saved_uic_err=0x%x\n",
>                 hba->saved_err, hba->saved_uic_err);
>         dev_err(hba->dev, "Device power mode=%d, UIC link
> state=%d\n",

Reviewed-by: Peter Wang <peter.wang@mediatek.com>

Re: [PATCH v2 0/2] Call scsi_host_busy() after the SCSI host has been added

[Martin K. Petersen]

On Fri, 09 Jan 2026 12:51:00 -0800, Bart Van Assche wrote:

> The UFS driver is the only SCSI driver I know of that may call
> scsi_host_busy() before the SCSI host has been added. This patch series
> modifies the UFS driver such that scsi_host_busy() is only called after the
> SCSI host has been added. Additionally, commit a0b7780602b1 ("scsi: core:
> Fix a regression triggered by scsi_host_busy()") is reverted because all
> scsi_host_busy() calls now happen after the corresponding SCSI host has
> been added.
> 
> [...]

Applied to 6.20/scsi-queue, thanks!

[1/2] ufs: core: Only call scsi_host_busy() after the SCSI host has been added
      https://git.kernel.org/mkp/scsi/c/202d5dadd3a0
[2/2] scsi: core: Revert "Fix a regression triggered by scsi_host_busy()"
      https://git.kernel.org/mkp/scsi/c/e60b57972099

-- 
Martin K. Petersen