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.
Changes from v2:
* Use host_put_index() throughout
* Put host index code together
Changes from v1:
* Added inline host_put_index() and its use
Signed-off-by: Lee Duncan <lduncan@xxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
---
drivers/scsi/hosts.c | 47 ++++++++++++++++++++++++++++++++++++++---------
1 file changed, 38 insertions(+), 9 deletions(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 8bb173e01084..a47944867e65 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>
@@ -42,8 +42,6 @@
#include "scsi_logging.h"
-static atomic_t scsi_host_next_hn = ATOMIC_INIT(0); /* host_no for next new host */
-
static void scsi_host_cls_release(struct device *dev)
{
@@ -304,6 +302,31 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
}
EXPORT_SYMBOL(scsi_add_host_with_dma);
+static DEFINE_SPINLOCK(host_index_lock);
+static DEFINE_IDA(host_index_ida);
+
+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;
+}
+
+static inline void host_put_index(int index)
+{
+ spin_lock(&host_index_lock);
+ ida_remove(&host_index_ida, index);
+ spin_unlock(&host_index_lock);
+}
+
static void scsi_host_dev_release(struct device *dev)
{
struct Scsi_Host *shost = dev_to_shost(dev);
@@ -337,6 +360,8 @@ static void scsi_host_dev_release(struct device *dev)
kfree(shost->shost_data);
+ host_put_index(shost->host_no);
+
if (parent)
put_device(parent);
kfree(shost);
@@ -370,6 +395,8 @@ 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 +415,11 @@ 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 +504,7 @@ 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 +520,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
fail_kthread:
kthread_stop(shost->ehandler);
+ fail_free_index:
+ host_put_index(index);
fail_kfree:
kfree(shost);
return NULL;
--
2.1.4
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