Re: [BK PATCH] SCSI host num allocation improvement

[Ben Collins <bcollins@debian.org>]

Here's one that actually compiles.

===== drivers/scsi/hosts.c 1.96 vs edited =====
--- 1.96/drivers/scsi/hosts.c	Mon Dec 29 16:38:10 2003
+++ edited/drivers/scsi/hosts.c	Thu Feb 26 22:00:33 2004
@@ -30,6 +30,7 @@
 #include <linux/list.h>
 #include <linux/completion.h>
 #include <linux/unistd.h>
+#include <linux/idr.h>
 
 #include <scsi/scsi_host.h>
 #include "scsi.h"
@@ -37,12 +38,15 @@
 #include "scsi_priv.h"
 #include "scsi_logging.h"
 
-
-static int scsi_host_next_hn;		/* host_no for next new host */
+static DECLARE_MUTEX(host_num_lock);
+static struct idr allocated_hosts;
 
 
 static void scsi_host_cls_release(struct class_device *class_dev)
 {
+	down(&host_num_lock);
+	idr_remove(&allocated_hosts, class_to_shost(class_dev)->host_no);
+	up(&host_num_lock);
 	put_device(&class_to_shost(class_dev)->shost_gendev);
 }
 
@@ -166,6 +170,7 @@
 	kfree(shost);
 }
 
+
 /**
  * scsi_host_alloc - register a scsi host adapter instance.
  * @sht:	pointer to scsi host template
@@ -214,7 +219,6 @@
 
 	init_MUTEX(&shost->scan_mutex);
 
-	shost->host_no = scsi_host_next_hn++; /* XXX(hch): still racy */
 	shost->dma_channel = 0xff;
 
 	/* These three are default values which can be overridden */
@@ -263,6 +267,11 @@
 	if (rval)
 		goto fail_kfree;
 
+	down(&host_num_lock);
+	idr_pre_get(&allocated_hosts, GFP_KERNEL);
+	shost->host_no = idr_get_new(&allocated_hosts, NULL);
+	up(&host_num_lock);
+
 	device_initialize(&shost->shost_gendev);
 	snprintf(shost->shost_gendev.bus_id, BUS_ID_SIZE, "host%d",
 		shost->host_no);
@@ -307,6 +316,9 @@
 
 void scsi_unregister(struct Scsi_Host *shost)
 {
+	down(&host_num_lock);
+	idr_remove(&allocated_hosts, shost->host_no);
+	up(&host_num_lock);
 	list_del(&shost->sht_legacy_list);
 	scsi_host_put(shost);
 }
@@ -361,6 +373,7 @@
 
 int scsi_init_hosts(void)
 {
+	idr_init(&allocated_hosts);
 	return class_register(&shost_class);
 }
 
-- 
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