Implement SCSI part of hotplug.
This must be done in a separate context as SCSI makes use of EH during
probing. Unfortunately, SCSI probing fails silently if EH is active.
ata_eh_scsi_hotplug() does its best to avoid such conditions but,
theoretically, it may fail to associate SCSI device to newly found ATA
device; however, the chance is very slim and I haven't experienced any
such event during testing.
Device removal synchronization is somewhat complex but I think I've
got it right and haven't seen it malfunction.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
---
drivers/scsi/libata-core.c | 1
drivers/scsi/libata-eh.c | 6 ++
drivers/scsi/libata-scsi.c | 124 ++++++++++++++++++++++++++++++++++++++++++++
drivers/scsi/libata.h | 1
include/linux/libata.h | 2 -
5 files changed, 132 insertions(+), 2 deletions(-)
9b6e334e9835c4941ff6dd39ddebaa56ff29ecdd
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 261fcd4..d9a664c 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -5365,6 +5365,7 @@ static void ata_host_init(struct ata_por
ap->msg_enable = ATA_MSG_DRV;
INIT_WORK(&ap->port_task, NULL, NULL);
+ INIT_WORK(&ap->hotplug_task, ata_scsi_hotplug, ap);
INIT_LIST_HEAD(&ap->eh_done_q);
/* set cable type */
diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index beaba8f..b37575b 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -286,9 +286,13 @@ void ata_scsi_error(struct Scsi_Host *ho
/* clean up */
spin_lock_irqsave(hs_lock, flags);
+ if (ap->flags & ATA_FLAG_SCSI_HOTPLUG)
+ queue_work(ata_scsi_wq, &ap->hotplug_task);
+
if (ap->flags & ATA_FLAG_RECOVERED)
ata_port_printk(ap, KERN_INFO, "EH complete\n");
- ap->flags &= ~ATA_FLAG_RECOVERED;
+
+ ap->flags &= ~(ATA_FLAG_SCSI_HOTPLUG | ATA_FLAG_RECOVERED);
spin_unlock_irqrestore(hs_lock, flags);
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index acfa26c..f5095cb 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -2786,3 +2786,127 @@ int ata_scsi_offline_dev(struct ata_devi
}
return 0;
}
+
+/**
+ * ata_scsi_remove_dev - remove attached SCSI device
+ * @dev: ATA device to remove attached SCSI device for
+ *
+ * This function is called from ata_eh_scsi_hotplug() and
+ * responsible for removing the SCSI device attached to @dev.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep).
+ */
+static void ata_scsi_remove_dev(struct ata_device *dev)
+{
+ struct ata_port *ap = dev->ap;
+ struct scsi_device *sdev;
+ unsigned long flags;
+
+ /* Alas, we need to grab scan_mutex to ensure SCSI device
+ * state doesn't change underneath us and thus
+ * scsi_device_get() always succeeds. The mutex locking can
+ * be removed if there is __scsi_device_get() interface which
+ * increments reference counts regardless of device state.
+ */
+ mutex_lock(&ap->host->scan_mutex);
+ spin_lock_irqsave(&ap->host_set->lock, flags);
+
+ /* clearing dev->sdev is protected by host_set lock */
+ sdev = dev->sdev;
+ dev->sdev = NULL;
+
+ if (sdev) {
+ /* If user initiated unplug races with us, sdev can go
+ * away underneath us after the host_set lock and
+ * scan_mutex are released. Hold onto it.
+ */
+ if (scsi_device_get(sdev) == 0) {
+ /* The following ensures the attached sdev is
+ * offline on return from ata_scsi_offline_dev()
+ * regardless it wins or loses the race
+ * against this function.
+ */
+ scsi_device_set_state(sdev, SDEV_OFFLINE);
+ } else {
+ WARN_ON(1);
+ sdev = NULL;
+ }
+ }
+
+ spin_unlock_irqrestore(&ap->host_set->lock, flags);
+ mutex_unlock(&ap->host->scan_mutex);
+
+ if (sdev) {
+ ata_dev_printk(dev, KERN_INFO, "detaching (SCSI %s)\n",
+ sdev->sdev_gendev.bus_id);
+
+ scsi_remove_device(sdev);
+ scsi_device_put(sdev);
+ }
+}
+
+/**
+ * ata_scsi_hotplug - SCSI part of hotplug
+ * @data: Pointer to ATA port to perform SCSI hotplug on
+ *
+ * Perform SCSI part of hotplug. It's executed from a separate
+ * workqueue after EH completes. This is necessary because SCSI
+ * hot plugging requires working EH and hot unplugging is
+ * synchronized with hot plugging with a mutex.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep).
+ */
+void ata_scsi_hotplug(void *data)
+{
+ struct ata_port *ap = data;
+ unsigned long timeout;
+ int i, requeue = 0;
+
+ DPRINTK("ENTER\n");
+
+ /* SCSI hotplug is requested. EH might still be running and
+ * we wanna scan the bus after EH is complete; otherwise,
+ * scsi_host_scan_allowed() test fails and SCSI scan is
+ * skipped silently. scsi_block_when_processing_errors()
+ * cannot be used because we might not have a sdev to wait on.
+ * Poll for !scsi_host_in_recovery() for 2 secs.
+ */
+ timeout = jiffies + 2 * HZ;
+ do {
+ if (!scsi_host_in_recovery(ap->host))
+ break;
+ msleep(100);
+ } while (time_before(jiffies, timeout));
+
+ if (scsi_host_in_recovery(ap->host))
+ requeue = 1;
+
+ /* unplug detached devices */
+ for (i = 0; i < ATA_MAX_DEVICES; i++) {
+ struct ata_device *dev = &ap->device[i];
+ unsigned long flags;
+
+ if (!(dev->flags & ATA_DFLAG_DETACHED))
+ continue;
+
+ spin_lock_irqsave(&ap->host_set->lock, flags);
+ dev->flags &= ~ATA_DFLAG_DETACHED;
+ spin_unlock_irqrestore(&ap->host_set->lock, flags);
+
+ ata_scsi_remove_dev(dev);
+ }
+
+ /* scan for new ones */
+ ata_scsi_scan_host(ap);
+
+ if (requeue || scsi_host_in_recovery(ap->host)) {
+ /* we might have scanned while EH is active. Repeat
+ * scan after a sec.
+ */
+ queue_delayed_work(ata_scsi_wq, &ap->hotplug_task, HZ);
+ }
+
+ DPRINTK("EXIT\n");
+}
diff --git a/drivers/scsi/libata.h b/drivers/scsi/libata.h
index 15628b8..2d8cc05 100644
--- a/drivers/scsi/libata.h
+++ b/drivers/scsi/libata.h
@@ -76,6 +76,7 @@ extern struct scsi_transport_template at
extern void ata_scsi_scan_host(struct ata_port *ap);
extern int ata_scsi_offline_dev(struct ata_device *dev);
+extern void ata_scsi_hotplug(void *data);
extern unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf,
unsigned int buflen);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index ef070b4..e20831c 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -520,7 +520,7 @@ struct ata_port {
struct ata_host_set *host_set;
struct device *dev;
- struct work_struct port_task;
+ struct work_struct port_task, hotplug_task;
unsigned int hsm_task_state;
--
1.3.2
-
: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
