Re: [PATCH 1/2] libiscsi: Fix locking in __iscsi_conn_send_pdu

[Lee Duncan]

On 10/12/2016 11:38 PM, Jitendra Bhivare wrote:
> The code at free_task label in __iscsi_conn_send_pdu can get executed
> from blk_timeout_work which takes queue_lock using spin_lock_irq.
> back_lock taken with spin_unlock_bh will cause WARN_ON_ONCE.
> The code gets executed either with bottom half or IRQ disabled hence
> using spin_lock/spin_unlock for back_lock is safe.
> 
> Signed-off-by: Jitendra Bhivare 
> ---
>  drivers/scsi/libiscsi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> index c051694..f9b6fba 100644
> --- a/drivers/scsi/libiscsi.c
> +++ b/drivers/scsi/libiscsi.c
> @@ -791,9 +791,9 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct 
> iscsi_hdr *hdr,
>  
>  free_task:
>   /* regular RX path uses back_lock */
> - spin_lock_bh(>back_lock);
> + spin_lock(>back_lock);
>   __iscsi_put_task(task);
> - spin_unlock_bh(>back_lock);
> + spin_unlock(>back_lock);
>   return NULL;
>  }
>  
> 

Reviewed-by: Lee Duncan 
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Re: [PATCH 1/2] libiscsi: Fix locking in __iscsi_conn_send_pdu

[Chris Leech]

On Thu, Oct 13, 2016 at 12:08:48PM +0530, Jitendra Bhivare wrote:
> The code at free_task label in __iscsi_conn_send_pdu can get executed
> from blk_timeout_work which takes queue_lock using spin_lock_irq.
> back_lock taken with spin_unlock_bh will cause WARN_ON_ONCE.
> The code gets executed either with bottom half or IRQ disabled hence
> using spin_lock/spin_unlock for back_lock is safe.
> 
> Signed-off-by: Jitendra Bhivare 
> ---
>  drivers/scsi/libiscsi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> index c051694..f9b6fba 100644
> --- a/drivers/scsi/libiscsi.c
> +++ b/drivers/scsi/libiscsi.c
> @@ -791,9 +791,9 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct 
> iscsi_hdr *hdr,
>  
>  free_task:
>   /* regular RX path uses back_lock */
> - spin_lock_bh(>back_lock);
> + spin_lock(>back_lock);
>   __iscsi_put_task(task);
> - spin_unlock_bh(>back_lock);
> + spin_unlock(>back_lock);
>   return NULL;
>  }
>  

Thanks for going back and verifying that irqsave wasn't needed here, I
was concerned about adding more interrupt disabled sections outside of
the error handling paths.

Reviewed-by: Chris Leech 

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Re: [PATCH 1/2] libiscsi: Fix locking in __iscsi_conn_send_pdu

[Hannes Reinecke]

On 10/13/2016 08:38 AM, Jitendra Bhivare wrote:
> The code at free_task label in __iscsi_conn_send_pdu can get executed
> from blk_timeout_work which takes queue_lock using spin_lock_irq.
> back_lock taken with spin_unlock_bh will cause WARN_ON_ONCE.
> The code gets executed either with bottom half or IRQ disabled hence
> using spin_lock/spin_unlock for back_lock is safe.
> 
> Signed-off-by: Jitendra Bhivare 
> ---
>  drivers/scsi/libiscsi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> index c051694..f9b6fba 100644
> --- a/drivers/scsi/libiscsi.c
> +++ b/drivers/scsi/libiscsi.c
> @@ -791,9 +791,9 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct 
> iscsi_hdr *hdr,
>  
>  free_task:
>   /* regular RX path uses back_lock */
> - spin_lock_bh(>back_lock);
> + spin_lock(>back_lock);
>   __iscsi_put_task(task);
> - spin_unlock_bh(>back_lock);
> + spin_unlock(>back_lock);
>   return NULL;
>  }
>  
> 
Reviewed-by: Hannes Reinecke 

Cheers,

Hannes
-- 
Dr. Hannes ReineckeTeamlead Storage & Networking
h...@suse.de   +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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