> I'm not sure it's possible to avoid such a race without introducing
> a new mutex. How about something like the (untested) SCSI core patch
> below, and invoking scsi_block_eh() and scsi_unblock_eh() around any
> reconnect activity not initiated from the SCSI EH thread ?
>
> [PATCH] Add scsi_block_eh() and scsi_unblock_eh()
>
Hi Bart,
The description doesn't match the code at all, do you mean try to
serialize the reconnect activity with this new block_eh_mutex?
Cheers,
Jack
> ---
> drivers/scsi/hosts.c | 1 +
> drivers/scsi/scsi_error.c | 10 ++++++++++
> include/scsi/scsi_host.h | 1 +
> 3 files changed, 12 insertions(+)
>
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index 17e2ccb..0df3ec8 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -360,6 +360,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
> init_waitqueue_head(&shost->host_wait);
>
> mutex_init(&shost->scan_mutex);
> + mutex_init(&shost->block_eh_mutex);
>
> /*
> * subtract one because we increment first then return, but we need to
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index ab16930..566daaa 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -551,6 +551,10 @@ static int scsi_begin_eh(struct Scsi_Host *host)
> {
> int res;
>
> + res = mutex_lock_interruptible(&host->block_eh_mutex);
> + if (res)
> + goto out;
> +
> spin_lock_irq(host->host_lock);
> switch (host->shost_state) {
> case SHOST_DEL:
> @@ -565,6 +569,10 @@ static int scsi_begin_eh(struct Scsi_Host *host)
> }
> spin_unlock_irq(host->host_lock);
>
> + if (res)
> + mutex_unlock(&host->block_eh_mutex);
> +
> +out:
> return res;
> }
>
> @@ -579,6 +587,8 @@ static void scsi_end_eh(struct Scsi_Host *host)
> if (host->eh_active == 0)
> wake_up(&host->host_wait);
> spin_unlock_irq(host->host_lock);
> +
> + mutex_unlock(&host->block_eh_mutex);
> }
>
> /**
> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
> index 9785e51..d7ce065 100644
> --- a/include/scsi/scsi_host.h
> +++ b/include/scsi/scsi_host.h
> @@ -573,6 +573,7 @@ struct Scsi_Host {
> spinlock_t *host_lock;
>
> struct mutex scan_mutex;/* serialize scanning activity */
> + struct mutex block_eh_mutex; /* block ML LLD EH calls */
>
> struct list_head eh_cmd_q;
> struct task_struct * ehandler; /* Error recovery thread. */
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