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Date: Mon, 5 Oct 2015 16:01:11 -0700
From: Lee Duncan <lduncan@...e.com>
To: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Lee Duncan <lduncan@...e.com>,
James Bottomley <James.Bottomley@...senPartnership.com>,
Tejun Heo <tj@...nel.org>, Hannes Reinecke <hare@...e.com>,
Johannes Thumshirn <jthumshirn@...e.de>,
Christoph Hellwig <hch@...radead.org>
Subject: [PATCHv2 1/1] SCSI: update hosts module to use idr index management
Update the SCSI hosts module to use idr to manage
its host_no index instead of an ATOMIC integer. This
also allows using idr_find() to look up the SCSI
host structure given the host number.
This means that the SCSI host number will now
be reclaimable.
Signed-off-by: Lee Duncan <lduncan@...e.com>
---
drivers/scsi/hosts.c | 60 +++++++++++++++++++++++++---------------------------
1 file changed, 29 insertions(+), 31 deletions(-)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 8bb173e01084..9dc8ff971f5a 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>
@@ -41,8 +41,8 @@
#include "scsi_priv.h"
#include "scsi_logging.h"
-
-static atomic_t scsi_host_next_hn = ATOMIC_INIT(0); /* host_no for next new host */
+static DEFINE_IDR(host_index_idr);
+static DEFINE_SPINLOCK(host_index_lock);
static void scsi_host_cls_release(struct device *dev)
@@ -337,6 +337,10 @@ static void scsi_host_dev_release(struct device *dev)
kfree(shost->shost_data);
+ spin_lock(&host_index_lock);
+ idr_remove(&host_index_idr, shost->host_no);
+ spin_unlock(&host_index_lock);
+
if (parent)
put_device(parent);
kfree(shost);
@@ -370,6 +374,7 @@ 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;
if (sht->unchecked_isa_dma && privsize)
gfp_mask |= __GFP_DMA;
@@ -388,11 +393,15 @@ 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;
+ idr_preload(GFP_KERNEL);
+ spin_lock(&host_index_lock);
+ index = idr_alloc(&host_index_idr, shost, 0, 0, GFP_NOWAIT);
+ spin_unlock(&host_index_lock);
+ idr_preload_end();
+ if (index < 0)
+ goto fail_kfree;
+ shost->host_no = index;
+
shost->dma_channel = 0xff;
/* These three are default values which can be overridden */
@@ -477,7 +486,7 @@ 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_idr_remove;
}
shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
@@ -493,6 +502,10 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
fail_kthread:
kthread_stop(shost->ehandler);
+ fail_idr_remove:
+ spin_lock(&host_index_lock);
+ idr_remove(&host_index_idr, shost->host_no);
+ spin_unlock(&host_index_lock);
fail_kfree:
kfree(shost);
return NULL;
@@ -522,37 +535,21 @@ void scsi_unregister(struct Scsi_Host *shost)
}
EXPORT_SYMBOL(scsi_unregister);
-static int __scsi_host_match(struct device *dev, const void *data)
-{
- struct Scsi_Host *p;
- const unsigned short *hostnum = data;
-
- p = class_to_shost(dev);
- return p->host_no == *hostnum;
-}
-
/**
* scsi_host_lookup - get a reference to a Scsi_Host by host no
* @hostnum: host number to locate
*
* Return value:
* A pointer to located Scsi_Host or NULL.
- *
- * The caller must do a scsi_host_put() to drop the reference
- * that scsi_host_get() took. The put_device() below dropped
- * the reference from class_find_device().
**/
struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
{
- struct device *cdev;
- struct Scsi_Host *shost = NULL;
-
- cdev = class_find_device(&shost_class, NULL, &hostnum,
- __scsi_host_match);
- if (cdev) {
- shost = scsi_host_get(class_to_shost(cdev));
- put_device(cdev);
- }
+ struct Scsi_Host *shost;
+
+ spin_lock(&host_index_lock);
+ shost = idr_find(&host_index_idr, hostnum);
+ spin_unlock(&host_index_lock);
+
return shost;
}
EXPORT_SYMBOL(scsi_host_lookup);
@@ -588,6 +585,7 @@ int scsi_init_hosts(void)
void scsi_exit_hosts(void)
{
class_unregister(&shost_class);
+ idr_destroy(&host_index_idr);
}
int scsi_is_host_device(const struct device *dev)
--
2.1.4
--
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