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Also call destroy_rcu_head() for passthrough requests

Message ID 20190318162926.50236-1-bvanassche@acm.org (mailing list archive)
State Mainlined
Commit db983f6eef57a9d78af79bc32389b7e60eb3c47d
Headers show
Series Also call destroy_rcu_head() for passthrough requests | expand

Commit Message

Bart Van Assche March 18, 2019, 4:29 p.m. UTC
cmd->rcu is initialized by scsi_initialize_rq(). For passthrough
requests, blk_get_request() calls scsi_initialize_rq(). For filesystem
requests, scsi_init_command() calls scsi_initialize_rq(). Make sure
that destroy_rcu_head() is called for passthrough requests.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reported-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_lib.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Comments

Hannes Reinecke March 19, 2019, 6:56 a.m. UTC | #1
On 3/18/19 5:29 PM, Bart Van Assche wrote:
> cmd->rcu is initialized by scsi_initialize_rq(). For passthrough
> requests, blk_get_request() calls scsi_initialize_rq(). For filesystem
> requests, scsi_init_command() calls scsi_initialize_rq(). Make sure
> that destroy_rcu_head() is called for passthrough requests.
> 
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: Ewan D. Milne <emilne@redhat.com>
> Cc: Johannes Thumshirn <jthumshirn@suse.de>
> Reported-by: Ewan D. Milne <emilne@redhat.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>   drivers/scsi/scsi_lib.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 33e1a72d47fa..ed4314f8542e 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -585,9 +585,16 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
>   	if (!blk_rq_is_scsi(req)) {
>   		WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));
>   		cmd->flags &= ~SCMD_INITIALIZED;
> -		destroy_rcu_head(&cmd->rcu);
>   	}
>   
> +	/*
> +	 * Calling rcu_barrier() is not necessary here because the
> +	 * SCSI error handler guarantees that the function called by
> +	 * call_rcu() has been called before scsi_end_request() is
> +	 * called.
> +	 */
> +	destroy_rcu_head(&cmd->rcu);
> +
>   	/*
>   	 * In the MQ case the command gets freed by __blk_mq_end_request,
>   	 * so we have to do all cleanup that depends on it earlier.
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
Martin K. Petersen March 19, 2019, 6:14 p.m. UTC | #2
Bart,

> cmd->rcu is initialized by scsi_initialize_rq(). For passthrough
> requests, blk_get_request() calls scsi_initialize_rq(). For filesystem
> requests, scsi_init_command() calls scsi_initialize_rq(). Make sure
> that destroy_rcu_head() is called for passthrough requests.

Applied to 5.1/scsi-fixes, thanks!
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Patch

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 33e1a72d47fa..ed4314f8542e 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -585,9 +585,16 @@  static bool scsi_end_request(struct request *req, blk_status_t error,
 	if (!blk_rq_is_scsi(req)) {
 		WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));
 		cmd->flags &= ~SCMD_INITIALIZED;
-		destroy_rcu_head(&cmd->rcu);
 	}
 
+	/*
+	 * Calling rcu_barrier() is not necessary here because the
+	 * SCSI error handler guarantees that the function called by
+	 * call_rcu() has been called before scsi_end_request() is
+	 * called.
+	 */
+	destroy_rcu_head(&cmd->rcu);
+
 	/*
 	 * In the MQ case the command gets freed by __blk_mq_end_request,
 	 * so we have to do all cleanup that depends on it earlier.