Message-Id: <f89fe3933ae899dc01f2eddd2a0cefac3383cf3c.1444241058.git.lduncan@suse.com>
In-Reply-To: <cover.1444241058.git.lduncan@suse.com>
References: <cover.1444241058.git.lduncan@suse.com>
From: Lee Duncan <lduncan@suse.com>
Date: Wed, 7 Oct 2015 11:00:41 -0700
Subject: [PATCH] SCSI: hosts: update to use ida_simple for host_no management
Patch-mainline: Submitted Wed, 7 Oct 2015 19:47:43 -0400 - linux-kernel@vger.kernel.org
Reference: bsc#939926

Update the SCSI hosts module to use the ida_simple*() routines
to manage its host_no index instead of an ATOMIC integer. This
means that the SCSI host number will now be reclaimable.

Signed-off-by: Lee Duncan <lduncan@suse.com>
---
 drivers/scsi/hosts.c |   22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

--- 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 +42,7 @@
 #include "scsi_logging.h"
 
 
-static atomic_t scsi_host_next_hn = ATOMIC_INIT(0);	/* host_no for next new host */
+static DEFINE_IDA(host_index_ida);
 
 
 static void scsi_host_cls_release(struct device *dev)
@@ -311,6 +311,8 @@ static void scsi_host_dev_release(struct
 
 	kfree(shost->shost_data);
 
+	ida_simple_remove(&host_index_ida, shost->host_no);
+
 	if (parent)
 		put_device(parent);
 	kfree(shost);
@@ -344,6 +346,7 @@ struct Scsi_Host *scsi_host_alloc(struct
 {
 	struct Scsi_Host *shost;
 	gfp_t gfp_mask = GFP_KERNEL;
+	int index;
 
 	if (sht->unchecked_isa_dma && privsize)
 		gfp_mask |= __GFP_DMA;
@@ -363,11 +366,11 @@ struct Scsi_Host *scsi_host_alloc(struct
 
 	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;
+	index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);
+	if (index < 0)
+		goto fail_kfree;
+	shost->host_no = index;
+
 	shost->dma_channel = 0xff;
 
 	/* These three are default values which can be overridden */
@@ -440,12 +443,14 @@ struct Scsi_Host *scsi_host_alloc(struct
 	if (IS_ERR(shost->ehandler)) {
 		printk(KERN_WARNING "scsi%d: error handler thread failed to spawn, error = %ld\n",
 			shost->host_no, PTR_ERR(shost->ehandler));
-		goto fail_kfree;
+		goto fail_index_remove;
 	}
 
 	scsi_proc_hostdir_add(shost->hostt);
 	return shost;
 
+ fail_index_remove:
+	ida_simple_remove(&host_index_ida, shost->host_no);
  fail_kfree:
 	kfree(shost);
 	return NULL;
@@ -541,6 +546,7 @@ int scsi_init_hosts(void)
 void scsi_exit_hosts(void)
 {
 	class_unregister(&shost_class);
+	ida_destroy(&host_index_ida);
 }
 
 int scsi_is_host_device(const struct device *dev)

