[PATCH 1/1] target: Use RCU helpers for INQUIRY t10_alua_tg_pt_gp use

[PATCH 1/1] target: Use RCU helpers for INQUIRY t10_alua_tg_pt_gp use

[Mike Christie]

This fixes the sparse warnings about t10_alua_tg_pt_gp accesses in
target_core_spc.c from:

commit 7324f47d4293 ("scsi: target: Replace lun_tg_pt_gp_lock with rcu in
I/O path")

That patch replaced the lun_tg_pt_gp_lock use in the IO path, but didn't
update the INQUIRY code.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/target/target_core_spc.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 22703a0dbd07..4c76498d3fb0 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -40,11 +40,11 @@ static void spc_fill_alua_data(struct se_lun *lun, unsigned char *buf)
 	 *
 	 * See spc4r17 section 6.4.2 Table 135
 	 */
-	spin_lock(&lun->lun_tg_pt_gp_lock);
-	tg_pt_gp = lun->lun_tg_pt_gp;
+	rcu_read_lock();
+	tg_pt_gp = rcu_dereference(lun->lun_tg_pt_gp);
 	if (tg_pt_gp)
 		buf[5] |= tg_pt_gp->tg_pt_gp_alua_access_type;
-	spin_unlock(&lun->lun_tg_pt_gp_lock);
+	rcu_read_unlock();
 }
 
 static u16
@@ -325,14 +325,14 @@ spc_emulate_evpd_83(struct se_cmd *cmd, unsigned char *buf)
 		 * Get the PROTOCOL IDENTIFIER as defined by spc4r17
 		 * section 7.5.1 Table 362
 		 */
-		spin_lock(&lun->lun_tg_pt_gp_lock);
-		tg_pt_gp = lun->lun_tg_pt_gp;
+		rcu_read_lock();
+		tg_pt_gp = rcu_dereference(lun->lun_tg_pt_gp);
 		if (!tg_pt_gp) {
-			spin_unlock(&lun->lun_tg_pt_gp_lock);
+			rcu_read_unlock();
 			goto check_lu_gp;
 		}
 		tg_pt_gp_id = tg_pt_gp->tg_pt_gp_id;
-		spin_unlock(&lun->lun_tg_pt_gp_lock);
+		rcu_read_unlock();
 
 		buf[off] = tpg->proto_id << 4;
 		buf[off++] |= 0x1; /* CODE SET == Binary */
-- 
2.25.1

Re: [PATCH 1/1] target: Use RCU helpers for INQUIRY t10_alua_tg_pt_gp use

[Maurizio Lombardi]

On Wed, Nov 17, 2021 at 03:39:28PM -0600, Mike Christie wrote:
> This fixes the sparse warnings about t10_alua_tg_pt_gp accesses in
> target_core_spc.c from:
> 
> commit 7324f47d4293 ("scsi: target: Replace lun_tg_pt_gp_lock with rcu in
> I/O path")
> 
> That patch replaced the lun_tg_pt_gp_lock use in the IO path, but didn't
> update the INQUIRY code.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Mike Christie <michael.christie@oracle.com>
> ---
>  drivers/target/target_core_spc.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
> index 22703a0dbd07..4c76498d3fb0 100644
> --- a/drivers/target/target_core_spc.c
> +++ b/drivers/target/target_core_spc.c
> @@ -40,11 +40,11 @@ static void spc_fill_alua_data(struct se_lun *lun, unsigned char *buf)
>  	 *
>  	 * See spc4r17 section 6.4.2 Table 135
>  	 */
> -	spin_lock(&lun->lun_tg_pt_gp_lock);
> -	tg_pt_gp = lun->lun_tg_pt_gp;
> +	rcu_read_lock();
> +	tg_pt_gp = rcu_dereference(lun->lun_tg_pt_gp);
>  	if (tg_pt_gp)
>  		buf[5] |= tg_pt_gp->tg_pt_gp_alua_access_type;
> -	spin_unlock(&lun->lun_tg_pt_gp_lock);
> +	rcu_read_unlock();
>  }
>  
>  static u16
> @@ -325,14 +325,14 @@ spc_emulate_evpd_83(struct se_cmd *cmd, unsigned char *buf)
>  		 * Get the PROTOCOL IDENTIFIER as defined by spc4r17
>  		 * section 7.5.1 Table 362
>  		 */
> -		spin_lock(&lun->lun_tg_pt_gp_lock);
> -		tg_pt_gp = lun->lun_tg_pt_gp;
> +		rcu_read_lock();
> +		tg_pt_gp = rcu_dereference(lun->lun_tg_pt_gp);
>  		if (!tg_pt_gp) {
> -			spin_unlock(&lun->lun_tg_pt_gp_lock);
> +			rcu_read_unlock();
>  			goto check_lu_gp;
>  		}
>  		tg_pt_gp_id = tg_pt_gp->tg_pt_gp_id;
> -		spin_unlock(&lun->lun_tg_pt_gp_lock);
> +		rcu_read_unlock();
>  
>  		buf[off] = tpg->proto_id << 4;
>  		buf[off++] |= 0x1; /* CODE SET == Binary */
> -- 
> 2.25.1
>

Looks ok,

Reviewed-by: Maurizio Lombardi <mlombard@redhat.com>

Re: [PATCH 1/1] target: Use RCU helpers for INQUIRY t10_alua_tg_pt_gp use

[Martin K. Petersen]

On Wed, 17 Nov 2021 15:39:28 -0600, Mike Christie wrote:

> This fixes the sparse warnings about t10_alua_tg_pt_gp accesses in
> target_core_spc.c from:
> 
> commit 7324f47d4293 ("scsi: target: Replace lun_tg_pt_gp_lock with rcu in
> I/O path")
> 
> That patch replaced the lun_tg_pt_gp_lock use in the IO path, but didn't
> update the INQUIRY code.
> 
> [...]

Applied to 5.16/scsi-fixes, thanks!

[1/1] target: Use RCU helpers for INQUIRY t10_alua_tg_pt_gp use
      https://git.kernel.org/mkp/scsi/c/e2a49a95b571

-- 
Martin K. Petersen	Oracle Linux Engineering