fastboot: make scsi probes asynchronous

This patch makes part of the scsi probe (which is mostly device spin up and the
partition scan) asynchronous. Only the part that runs after getting the device
number allocated is asynchronous, ensuring that device numbering remains stable.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

drivers/scsi/scsi_scan.c

@@ -32,6 +32,7 @@
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/spinlock.h>
+#include <linux/async.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
@@ -179,6 +180,8 @@ int scsi_complete_async_scans(void)
 	spin_unlock(&async_scan_lock);
 
 	kfree(data);
+	/* Synchronize async operations globally */
+	async_synchronize_full();
 	return 0;
 }
 

drivers/scsi/sd.c

@@ -48,6 +48,7 @@
 #include <linux/delay.h>
 #include <linux/mutex.h>
 #include <linux/string_helpers.h>
+#include <linux/async.h>
 #include <asm/uaccess.h>
 
 #include <scsi/scsi.h>
@@ -1802,6 +1803,71 @@ static int sd_format_disk_name(char *prefix, int index, char *buf, int buflen)
 	return 0;
 }
 
+/*
+ * The asynchronous part of sd_probe
+ */
+static void sd_probe_async(void *data, async_cookie_t cookie)
+{
+	struct scsi_disk *sdkp = data;
+	struct scsi_device *sdp;
+	struct gendisk *gd;
+	u32 index;
+	struct device *dev;
+
+	sdp = sdkp->device;
+	gd = sdkp->disk;
+	index = sdkp->index;
+	dev = &sdp->sdev_gendev;
+
+	if (!sdp->request_queue->rq_timeout) {
+		if (sdp->type != TYPE_MOD)
+			blk_queue_rq_timeout(sdp->request_queue, SD_TIMEOUT);
+		else
+			blk_queue_rq_timeout(sdp->request_queue,
+					     SD_MOD_TIMEOUT);
+	}
+
+	device_initialize(&sdkp->dev);
+	sdkp->dev.parent = &sdp->sdev_gendev;
+	sdkp->dev.class = &sd_disk_class;
+	strncpy(sdkp->dev.bus_id, sdp->sdev_gendev.bus_id, BUS_ID_SIZE);
+
+	if (device_add(&sdkp->dev))
+		goto out_free_index;
+
+	get_device(&sdp->sdev_gendev);
+
+	if (index < SD_MAX_DISKS) {
+		gd->major = sd_major((index & 0xf0) >> 4);
+		gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
+		gd->minors = SD_MINORS;
+	}
+	gd->fops = &sd_fops;
+	gd->private_data = &sdkp->driver;
+	gd->queue = sdkp->device->request_queue;
+
+	sd_revalidate_disk(gd);
+
+	blk_queue_prep_rq(sdp->request_queue, sd_prep_fn);
+
+	gd->driverfs_dev = &sdp->sdev_gendev;
+	gd->flags = GENHD_FL_EXT_DEVT | GENHD_FL_DRIVERFS;
+	if (sdp->removable)
+		gd->flags |= GENHD_FL_REMOVABLE;
+
+	dev_set_drvdata(dev, sdkp);
+	add_disk(gd);
+	sd_dif_config_host(sdkp);
+
+	sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
+		  sdp->removable ? "removable " : "");
+
+	return;
+
+ out_free_index:
+	ida_remove(&sd_index_ida, index);
+}
+
 /**
  *	sd_probe - called during driver initialization and whenever a
  *	new scsi device is attached to the system. It is called once
@@ -1865,48 +1931,7 @@ static int sd_probe(struct device *dev)
 	sdkp->openers = 0;
 	sdkp->previous_state = 1;
 
-	if (!sdp->request_queue->rq_timeout) {
-		if (sdp->type != TYPE_MOD)
-			blk_queue_rq_timeout(sdp->request_queue, SD_TIMEOUT);
-		else
-			blk_queue_rq_timeout(sdp->request_queue,
-					     SD_MOD_TIMEOUT);
-	}
-
-	device_initialize(&sdkp->dev);
-	sdkp->dev.parent = &sdp->sdev_gendev;
-	sdkp->dev.class = &sd_disk_class;
-	strncpy(sdkp->dev.bus_id, sdp->sdev_gendev.bus_id, BUS_ID_SIZE);
-
-	if (device_add(&sdkp->dev))
-		goto out_free_index;
-
-	get_device(&sdp->sdev_gendev);
-
-	if (index < SD_MAX_DISKS) {
-		gd->major = sd_major((index & 0xf0) >> 4);
-		gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
-		gd->minors = SD_MINORS;
-	}
-	gd->fops = &sd_fops;
-	gd->private_data = &sdkp->driver;
-	gd->queue = sdkp->device->request_queue;
-
-	sd_revalidate_disk(gd);
-
-	blk_queue_prep_rq(sdp->request_queue, sd_prep_fn);
-
-	gd->driverfs_dev = &sdp->sdev_gendev;
-	gd->flags = GENHD_FL_EXT_DEVT | GENHD_FL_DRIVERFS;
-	if (sdp->removable)
-		gd->flags |= GENHD_FL_REMOVABLE;
-
-	dev_set_drvdata(dev, sdkp);
-	add_disk(gd);
-	sd_dif_config_host(sdkp);
-
-	sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
-		  sdp->removable ? "removable " : "");
+	async_schedule(sd_probe_async, sdkp);
 
 	return 0;