leeman.duncan@xxxxxxxxx writes:
> From: Lee Duncan <lduncan@xxxxxxxx>
>
> Each Scsi_host instance gets a host number starting
> at 0, but this is implemented with an atomic integer,
> and rollover doesn't seem to have been considered.
> Another side-effect of this design is that scsi host
> numbers used by iscsi are never reused, thereby making
> rollover more likely. This patch converts Scsi_host
> instances to use ida to manage their instance
> numbers.
>
> This also means that host instance numbers will be
> reused, when available.
>
> Signed-off-by: Lee Duncan <lduncan@xxxxxxxx>
> ---
> drivers/scsi/hosts.c | 43 +++++++++++++++++++++++++++++++++++--------
> 1 file changed, 35 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index 8bb173e01084..dade75478541 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -33,7 +33,7 @@
> #include <linux/transport_class.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> -
> +#include <linux/idr.h>
> #include <scsi/scsi_device.h>
> #include <scsi/scsi_host.h>
> #include <scsi/scsi_transport.h>
> @@ -42,7 +42,8 @@
> #include "scsi_logging.h"
>
>
> -static atomic_t scsi_host_next_hn = ATOMIC_INIT(0); /* host_no for next new host */
> +static DEFINE_SPINLOCK(host_index_lock);
> +static DEFINE_IDA(host_index_ida);
>
>
> static void scsi_host_cls_release(struct device *dev)
> @@ -337,6 +338,10 @@ static void scsi_host_dev_release(struct device *dev)
>
> kfree(shost->shost_data);
>
> + spin_lock(&host_index_lock);
> + ida_remove(&host_index_ida, shost->host_no);
> + spin_unlock(&host_index_lock);
> +
> if (parent)
> put_device(parent);
> kfree(shost);
> @@ -353,6 +358,22 @@ static struct device_type scsi_host_type = {
> .release = scsi_host_dev_release,
> };
>
> +static int host_get_index(int *index)
> +{
> + int error = -ENOMEM;
> +
> + do {
> + if (!ida_pre_get(&host_index_ida, GFP_KERNEL))
> + break;
> + spin_lock(&host_index_lock);
> + error = ida_get_new(&host_index_ida, index);
> + spin_unlock(&host_index_lock);
> + } while (error == -EAGAIN);
> +
> + return error;
> +}
> +
> +
> /**
> * scsi_host_alloc - register a scsi host adapter instance.
> * @sht: pointer to scsi host template
> @@ -370,6 +391,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
> {
> struct Scsi_Host *shost;
> gfp_t gfp_mask = GFP_KERNEL;
> + int index;
> + int error;
>
> if (sht->unchecked_isa_dma && privsize)
> gfp_mask |= __GFP_DMA;
> @@ -388,11 +411,11 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
> init_waitqueue_head(&shost->host_wait);
> mutex_init(&shost->scan_mutex);
>
> - /*
> - * subtract one because we increment first then return, but we need to
> - * know what the next host number was before increment
> - */
> - shost->host_no = atomic_inc_return(&scsi_host_next_hn) - 1;
> + error = host_get_index(&index);
> + if (error < 0)
> + goto fail_kfree;
> + shost->host_no = index;
> +
> shost->dma_channel = 0xff;
>
> /* These three are default values which can be overridden */
> @@ -477,7 +500,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
> shost_printk(KERN_WARNING, shost,
> "error handler thread failed to spawn, error = %ld\n",
> PTR_ERR(shost->ehandler));
> - goto fail_kfree;
> + goto fail_free_index;
> }
>
> shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
> @@ -493,6 +516,10 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
>
> fail_kthread:
> kthread_stop(shost->ehandler);
> + fail_free_index:
> + spin_lock(&host_index_lock);
> + ida_remove(&host_index_ida, index);
> + spin_unlock(&host_index_lock);
> fail_kfree:
> kfree(shost);
> return NULL;
Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
--
Johannes Thumshirn Storage
jthumshirn@xxxxxxx +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850
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