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Subject[PATCH v4 1/2] SCSI: Asynchronous event notification infrastructure
Date
Originally based on a patch by Kristen Carlson Accardi @ Intel.
Copious input from James Bottomley.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
---
drivers/scsi/scsi_lib.c | 66 ++++++++++++++++++++++++++++++++++++++++++++
drivers/scsi/scsi_scan.c | 2 +
drivers/scsi/scsi_sysfs.c | 20 +++++++++++++
include/scsi/scsi_device.h | 12 ++++++++
4 files changed, 100 insertions(+), 0 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 61fdaf0..f55ec80 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -18,6 +18,7 @@
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <linux/scatterlist.h>
+#include <linux/bitmap.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
@@ -2115,6 +2116,71 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
EXPORT_SYMBOL(scsi_device_set_state);

/**
+ * sdev_evt_thread - send a uevent for each scsi event
+ * @work: work struct for scsi_device
+ *
+ * Emit all queued media events as environment variables
+ * sent during a uevent.
+ */
+void scsi_evt_thread(struct work_struct *work)
+{
+ struct scsi_device *sdev;
+ char *envp[SDEV_EVT_LAST + 2];
+ DECLARE_BITMAP(mask, SDEV_EVT_MAXBITS);
+ unsigned long flags;
+ int evt, idx;
+
+ sdev = container_of(work, struct scsi_device, event_work);
+
+ spin_lock_irqsave(&sdev->list_lock, flags);
+ bitmap_copy(mask, sdev->event_mask, SDEV_EVT_MAXBITS);
+ bitmap_zero(sdev->event_mask, SDEV_EVT_MAXBITS);
+ spin_unlock_irqrestore(&sdev->list_lock, flags);
+
+ idx = 0;
+ for (evt = 0; evt < SDEV_EVT_LAST; evt++) {
+ if (!test_bit(evt, mask))
+ continue;
+
+ switch (evt) {
+ case SDEV_EVT_MEDIA_CHANGE:
+ envp[idx++] = "SDEV_MEDIA_CHANGE=1";
+ break;
+ }
+ }
+ envp[idx++] = NULL;
+
+ kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
+}
+
+/**
+ * sdev_evt_notify - send asserted events to uevent thread
+ * @sdev: scsi_device event occurred on
+ * @map: the bitmapped list of asserted events (SDEV_EVT_xxx)
+ *
+ *
+ */
+void sdev_evt_notify(struct scsi_device *sdev, const unsigned long *map)
+{
+ DECLARE_BITMAP(tmp_map, SDEV_EVT_MAXBITS);
+ unsigned long flags;
+
+ spin_lock_irqsave(&sdev->list_lock, flags);
+
+ bitmap_and(tmp_map, sdev->supported_events, map, SDEV_EVT_MAXBITS);
+
+ if (!bitmap_empty(tmp_map, SDEV_EVT_MAXBITS)) {
+ bitmap_or(sdev->event_mask, sdev->event_mask, tmp_map,
+ SDEV_EVT_MAXBITS);
+
+ schedule_work(&sdev->event_work);
+ }
+
+ spin_unlock_irqrestore(&sdev->list_lock, flags);
+}
+EXPORT_SYMBOL_GPL(sdev_evt_notify);
+
+/**
* scsi_device_quiesce - Block user issued commands.
* @sdev: scsi device to quiesce.
*
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index b53c5f6..3632b62 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -236,6 +236,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
struct scsi_device *sdev;
int display_failure_msg = 1, ret;
struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ extern void scsi_evt_thread(struct work_struct *work);

sdev = kzalloc(sizeof(*sdev) + shost->transportt->device_size,
GFP_ATOMIC);
@@ -255,6 +256,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
INIT_LIST_HEAD(&sdev->cmd_list);
INIT_LIST_HEAD(&sdev->starved_entry);
spin_lock_init(&sdev->list_lock);
+ INIT_WORK(&sdev->event_work, scsi_evt_thread);

sdev->sdev_gendev.parent = get_device(&starget->dev);
sdev->sdev_target = starget;
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index d531cee..9a1b0c5 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -282,6 +282,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
list_del(&sdev->starved_entry);
spin_unlock_irqrestore(sdev->host->host_lock, flags);

+ cancel_work_sync(&sdev->event_work);
+
if (sdev->request_queue) {
sdev->request_queue->queuedata = NULL;
/* user context needed to free queue */
@@ -614,6 +616,23 @@ sdev_show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
}
static DEVICE_ATTR(modalias, S_IRUGO, sdev_show_modalias, NULL);

+#define DECLARE_EVT_SHOW(name, Cap_name) \
+static ssize_t \
+sdev_show_##name(struct device *dev, struct device_attribute *attr, \
+ char *buf) \
+{ \
+ struct scsi_device *sdev = to_scsi_device(dev); \
+ int val = test_bit(SDEV_EVT_##Cap_name, sdev->supported_events);\
+ return snprintf(buf, 20, "%d\n", val); \
+}
+
+#define DECLARE_EVT(name, Cap_name) \
+ DECLARE_EVT_SHOW(name, Cap_name) \
+ static DEVICE_ATTR(evt_##name, S_IRUGO, sdev_show_##name, NULL);
+#define REF_EVT(name) &dev_attr_evt_##name.attr
+
+DECLARE_EVT(media_change, MEDIA_CHANGE)
+
/* Default template for device attributes. May NOT be modified */
static struct attribute *scsi_sdev_attrs[] = {
&dev_attr_device_blocked.attr,
@@ -631,6 +650,7 @@ static struct attribute *scsi_sdev_attrs[] = {
&dev_attr_iodone_cnt.attr,
&dev_attr_ioerr_cnt.attr,
&dev_attr_modalias.attr,
+ REF_EVT(media_change),
NULL
};

diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index d5057bc..063827a 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -46,6 +46,13 @@ enum scsi_device_state {
* to the scsi lld. */
};

+enum scsi_device_event {
+ SDEV_EVT_MEDIA_CHANGE = 1, /* media has changed */
+
+ SDEV_EVT_LAST = SDEV_EVT_MEDIA_CHANGE,
+ SDEV_EVT_MAXBITS = SDEV_EVT_LAST + 1
+};
+
struct scsi_device {
struct Scsi_Host *host;
struct request_queue *request_queue;
@@ -127,6 +134,10 @@ struct scsi_device {
unsigned guess_capacity:1; /* READ_CAPACITY might be too high by 1 */
unsigned retry_hwerror:1; /* Retry HARDWARE_ERROR */

+ DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
+ DECLARE_BITMAP(event_mask, SDEV_EVT_MAXBITS); /* asserted events */
+ struct work_struct event_work;
+
unsigned int device_blocked; /* Device returned QUEUE_FULL. */

unsigned int max_device_blocked; /* what device_blocked counts down from */
@@ -275,6 +286,7 @@ extern int scsi_test_unit_ready(struct scsi_device *sdev, int timeout,
int retries);
extern int scsi_device_set_state(struct scsi_device *sdev,
enum scsi_device_state state);
+extern void sdev_evt_notify(struct scsi_device *sdev, const unsigned long *map);
extern int scsi_device_quiesce(struct scsi_device *sdev);
extern void scsi_device_resume(struct scsi_device *sdev);
extern void scsi_target_quiesce(struct scsi_target *);
--
1.5.2.4
-
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