[PATCH 1/2] scsi: fnic: Replace fnic->lock_flags with local flags

[PATCH 1/2] scsi: fnic: Replace fnic->lock_flags with local flags

[Karan Tilak Kumar]

Replace fnic->lock_flags with local variable for usage with spinlocks
in fdls_schedule_oxid_free_retry_work.

Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: a63e78eb2b0f ("scsi: fnic: Add support for fabric based solicited requests and responses")
Reviewed-by: Sesidhar Baddela <sebaddel@cisco.com>
Reviewed-by: Arulprabhu Ponnusamy <arulponn@cisco.com>
Reviewed-by: Gian Carlo Boffa <gcboffa@cisco.com>
Reviewed-by: Arun Easi <aeasi@cisco.com>
Signed-off-by: Karan Tilak Kumar <kartilak@cisco.com>
---
 drivers/scsi/fnic/fdls_disc.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/fnic/fdls_disc.c b/drivers/scsi/fnic/fdls_disc.c
index 3a41e92d5fd6..8843d9486dbb 100644
--- a/drivers/scsi/fnic/fdls_disc.c
+++ b/drivers/scsi/fnic/fdls_disc.c
@@ -308,23 +308,24 @@ void fdls_schedule_oxid_free_retry_work(struct work_struct *work)
 	struct fnic *fnic = iport->fnic;
 	struct reclaim_entry_s *reclaim_entry;
 	unsigned long delay_j = msecs_to_jiffies(OXID_RECLAIM_TOV(iport));
+	unsigned long flags;
 	int idx;
 
-	spin_lock_irqsave(&fnic->fnic_lock, fnic->lock_flags);
+	spin_lock_irqsave(&fnic->fnic_lock, flags);
 
 	for_each_set_bit(idx, oxid_pool->pending_schedule_free, FNIC_OXID_POOL_SZ) {
 
 		FNIC_FCS_DBG(KERN_INFO, fnic->host, fnic->fnic_num,
 			"Schedule oxid free. oxid idx: %d\n", idx);
 
-		spin_unlock_irqrestore(&fnic->fnic_lock, fnic->lock_flags);
+		spin_unlock_irqrestore(&fnic->fnic_lock, flags);
 		reclaim_entry = kzalloc(sizeof(*reclaim_entry), GFP_KERNEL);
-		spin_lock_irqsave(&fnic->fnic_lock, fnic->lock_flags);
+		spin_lock_irqsave(&fnic->fnic_lock, flags);
 
 		if (!reclaim_entry) {
 			schedule_delayed_work(&oxid_pool->schedule_oxid_free_retry,
 				msecs_to_jiffies(SCHEDULE_OXID_FREE_RETRY_TIME));
-			spin_unlock_irqrestore(&fnic->fnic_lock, fnic->lock_flags);
+			spin_unlock_irqrestore(&fnic->fnic_lock, flags);
 			return;
 		}
 
@@ -339,7 +340,7 @@ void fdls_schedule_oxid_free_retry_work(struct work_struct *work)
 		}
 	}
 
-	spin_unlock_irqrestore(&fnic->fnic_lock, fnic->lock_flags);
+	spin_unlock_irqrestore(&fnic->fnic_lock, flags);
 }
 
 static bool fdls_is_oxid_fabric_req(uint16_t oxid)
-- 
2.47.1

[PATCH 2/2] scsi: fnic: Remove unnecessary spinlock locking and unlocking

[Karan Tilak Kumar]

Remove unnecessary locking and unlocking of spinlock in
fdls_schedule_oxid_free_retry_work.
This will shorten the time in the critical section.

Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: a63e78eb2b0f ("scsi: fnic: Add support for fabric based solicited requests and responses")
Reviewed-by: Sesidhar Baddela <sebaddel@cisco.com>
Reviewed-by: Arulprabhu Ponnusamy <arulponn@cisco.com>
Reviewed-by: Gian Carlo Boffa <gcboffa@cisco.com>
Reviewed-by: Arun Easi <aeasi@cisco.com>
Tested-by: Karan Tilak Kumar <kartilak@cisco.com>
Signed-off-by: Karan Tilak Kumar <kartilak@cisco.com>
---
 drivers/scsi/fnic/fdls_disc.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/fnic/fdls_disc.c b/drivers/scsi/fnic/fdls_disc.c
index 8843d9486dbb..6530298733f0 100644
--- a/drivers/scsi/fnic/fdls_disc.c
+++ b/drivers/scsi/fnic/fdls_disc.c
@@ -311,36 +311,30 @@ void fdls_schedule_oxid_free_retry_work(struct work_struct *work)
 	unsigned long flags;
 	int idx;
 
-	spin_lock_irqsave(&fnic->fnic_lock, flags);
-
 	for_each_set_bit(idx, oxid_pool->pending_schedule_free, FNIC_OXID_POOL_SZ) {
 
 		FNIC_FCS_DBG(KERN_INFO, fnic->host, fnic->fnic_num,
 			"Schedule oxid free. oxid idx: %d\n", idx);
 
-		spin_unlock_irqrestore(&fnic->fnic_lock, flags);
 		reclaim_entry = kzalloc(sizeof(*reclaim_entry), GFP_KERNEL);
-		spin_lock_irqsave(&fnic->fnic_lock, flags);
-
 		if (!reclaim_entry) {
 			schedule_delayed_work(&oxid_pool->schedule_oxid_free_retry,
 				msecs_to_jiffies(SCHEDULE_OXID_FREE_RETRY_TIME));
-			spin_unlock_irqrestore(&fnic->fnic_lock, flags);
 			return;
 		}
 
 		if (test_and_clear_bit(idx, oxid_pool->pending_schedule_free)) {
 			reclaim_entry->oxid_idx = idx;
 			reclaim_entry->expires = round_jiffies(jiffies + delay_j);
+			spin_lock_irqsave(&fnic->fnic_lock, flags);
 			list_add_tail(&reclaim_entry->links, &oxid_pool->oxid_reclaim_list);
+			spin_unlock_irqrestore(&fnic->fnic_lock, flags);
 			schedule_delayed_work(&oxid_pool->oxid_reclaim_work, delay_j);
 		} else {
 			/* unlikely scenario, free the allocated memory and continue */
 			kfree(reclaim_entry);
 		}
 	}
-
-	spin_unlock_irqrestore(&fnic->fnic_lock, flags);
 }
 
 static bool fdls_is_oxid_fabric_req(uint16_t oxid)
-- 
2.47.1

Re: [PATCH 2/2] scsi: fnic: Remove unnecessary spinlock locking and unlocking

[Dan Carpenter]

On Tue, Feb 25, 2025 at 01:51:46PM -0800, Karan Tilak Kumar wrote:
> diff --git a/drivers/scsi/fnic/fdls_disc.c b/drivers/scsi/fnic/fdls_disc.c
> index 8843d9486dbb..6530298733f0 100644
> --- a/drivers/scsi/fnic/fdls_disc.c
> +++ b/drivers/scsi/fnic/fdls_disc.c
> @@ -311,36 +311,30 @@ void fdls_schedule_oxid_free_retry_work(struct work_struct *work)
>  	unsigned long flags;
>  	int idx;
>  
> -	spin_lock_irqsave(&fnic->fnic_lock, flags);
> -
>  	for_each_set_bit(idx, oxid_pool->pending_schedule_free, FNIC_OXID_POOL_SZ) {
>  
>  		FNIC_FCS_DBG(KERN_INFO, fnic->host, fnic->fnic_num,
>  			"Schedule oxid free. oxid idx: %d\n", idx);
>  
> -		spin_unlock_irqrestore(&fnic->fnic_lock, flags);
>  		reclaim_entry = kzalloc(sizeof(*reclaim_entry), GFP_KERNEL);
> -		spin_lock_irqsave(&fnic->fnic_lock, flags);
> -
>  		if (!reclaim_entry) {
>  			schedule_delayed_work(&oxid_pool->schedule_oxid_free_retry,
>  				msecs_to_jiffies(SCHEDULE_OXID_FREE_RETRY_TIME));
> -			spin_unlock_irqrestore(&fnic->fnic_lock, flags);
>  			return;
>  		}
>  
>  		if (test_and_clear_bit(idx, oxid_pool->pending_schedule_free)) {

We discussed this earlier and I really should have brought it up then,
but what is this check about?  We "know" (scare quotes) that it is true
because we're inside a for_each_set_bit() loop.  I had assumed it was to
test for race conditions so that's why I put it under the lock.  If the
locking doesn't matter then we could just do a clear_bit() without doing
a second test.

regards,
dan carpenter

>  			reclaim_entry->oxid_idx = idx;
>  			reclaim_entry->expires = round_jiffies(jiffies + delay_j);
> +			spin_lock_irqsave(&fnic->fnic_lock, flags);
>  			list_add_tail(&reclaim_entry->links, &oxid_pool->oxid_reclaim_list);
> +			spin_unlock_irqrestore(&fnic->fnic_lock, flags);
>  			schedule_delayed_work(&oxid_pool->oxid_reclaim_work, delay_j);
>  		} else {
>  			/* unlikely scenario, free the allocated memory and continue */
>  			kfree(reclaim_entry);
>  		}
>  	}

> -
> -	spin_unlock_irqrestore(&fnic->fnic_lock, flags);
>  }
>  
>  static bool fdls_is_oxid_fabric_req(uint16_t oxid)
> -- 
> 2.47.1

RE: [PATCH 2/2] scsi: fnic: Remove unnecessary spinlock locking and unlocking

[Karan Tilak Kumar (kartilak)]

On Tuesday, February 25, 2025 11:32 PM, Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> On Tue, Feb 25, 2025 at 01:51:46PM -0800, Karan Tilak Kumar wrote:
> > diff --git a/drivers/scsi/fnic/fdls_disc.c b/drivers/scsi/fnic/fdls_disc.c
> > index 8843d9486dbb..6530298733f0 100644
> > --- a/drivers/scsi/fnic/fdls_disc.c
> > +++ b/drivers/scsi/fnic/fdls_disc.c
> > @@ -311,36 +311,30 @@ void fdls_schedule_oxid_free_retry_work(struct work_struct *work)
> >     unsigned long flags;
> >     int idx;
> >
> > -   spin_lock_irqsave(&fnic->fnic_lock, flags);
> > -
> >     for_each_set_bit(idx, oxid_pool->pending_schedule_free, FNIC_OXID_POOL_SZ) {
> >
> >             FNIC_FCS_DBG(KERN_INFO, fnic->host, fnic->fnic_num,
> >                     "Schedule oxid free. oxid idx: %d\n", idx);
> >
> > -           spin_unlock_irqrestore(&fnic->fnic_lock, flags);
> >             reclaim_entry = kzalloc(sizeof(*reclaim_entry), GFP_KERNEL);
> > -           spin_lock_irqsave(&fnic->fnic_lock, flags);
> > -
> >             if (!reclaim_entry) {
> >                     schedule_delayed_work(&oxid_pool->schedule_oxid_free_retry,
> >                             msecs_to_jiffies(SCHEDULE_OXID_FREE_RETRY_TIME));
> > -                   spin_unlock_irqrestore(&fnic->fnic_lock, flags);
> >                     return;
> >             }
> >
> >             if (test_and_clear_bit(idx, oxid_pool->pending_schedule_free)) {
>
> We discussed this earlier and I really should have brought it up then,
> but what is this check about?  We "know" (scare quotes) that it is true
> because we're inside a for_each_set_bit() loop.  I had assumed it was to
> test for race conditions so that's why I put it under the lock.  If the
> locking doesn't matter then we could just do a clear_bit() without doing
> a second test.
>
> regards,
> dan carpenter
>
> >                     reclaim_entry->oxid_idx = idx;
> >                     reclaim_entry->expires = round_jiffies(jiffies + delay_j);
> > +                   spin_lock_irqsave(&fnic->fnic_lock, flags);
> >                     list_add_tail(&reclaim_entry->links, &oxid_pool->oxid_reclaim_list);
> > +                   spin_unlock_irqrestore(&fnic->fnic_lock, flags);
> >                     schedule_delayed_work(&oxid_pool->oxid_reclaim_work, delay_j);
> >             } else {
> >                     /* unlikely scenario, free the allocated memory and continue */
> >                     kfree(reclaim_entry);
> >             }
> >     }
>
> > -
> > -   spin_unlock_irqrestore(&fnic->fnic_lock, flags);
> >  }
> >
> >  static bool fdls_is_oxid_fabric_req(uint16_t oxid)
> > --
> > 2.47.1
>

Thanks for your review and comments, Dan.
You are right; We reviewed it, and locking is only needed to add to the reclaim list.
We can use clear_bit. I'll send out a revised patch for this.

Regards,
Karan (on behalf of the Cisco team)