In order to use the new execute_in_process_context() API, you have to
provide it with the work storage, which I do in SCSI in scsi_device and
scsi_target, but which also means that we can no longer queue up the
target reaps, so instead I moved the target to a state model which
allows target_alloc to detect if we've received a dying target and wait
for it to be gone. Hopefully, this should also solve the target
namespace race.
James
---
Index: BUILD-2.6/drivers/scsi/scsi_lib.c
===================================================================
--- BUILD-2.6.orig/drivers/scsi/scsi_lib.c 2006-02-20 08:57:40.000000000 -0600
+++ BUILD-2.6/drivers/scsi/scsi_lib.c 2006-02-23 12:37:21.000000000 -0600
@@ -2248,61 +2248,3 @@
device_for_each_child(dev, NULL, target_unblock);
}
EXPORT_SYMBOL_GPL(scsi_target_unblock);
-
-
-struct work_queue_work {
- struct work_struct work;
- void (*fn)(void *);
- void *data;
-};
-
-static void execute_in_process_context_work(void *data)
-{
- void (*fn)(void *data);
- struct work_queue_work *wqw = data;
-
- fn = wqw->fn;
- data = wqw->data;
-
- kfree(wqw);
-
- fn(data);
-}
-
-/**
- * scsi_execute_in_process_context - reliably execute the routine with user context
- * @fn: the function to execute
- * @data: data to pass to the function
- *
- * Executes the function immediately if process context is available,
- * otherwise schedules the function for delayed execution.
- *
- * Returns: 0 - function was executed
- * 1 - function was scheduled for execution
- * <0 - error
- */
-int scsi_execute_in_process_context(void (*fn)(void *data), void *data)
-{
- struct work_queue_work *wqw;
-
- if (!in_interrupt()) {
- fn(data);
- return 0;
- }
-
- wqw = kmalloc(sizeof(struct work_queue_work), GFP_ATOMIC);
-
- if (unlikely(!wqw)) {
- printk(KERN_ERR "Failed to allocate memory\n");
- WARN_ON(1);
- return -ENOMEM;
- }
-
- INIT_WORK(&wqw->work, execute_in_process_context_work, wqw);
- wqw->fn = fn;
- wqw->data = data;
- schedule_work(&wqw->work);
-
- return 1;
-}
-EXPORT_SYMBOL_GPL(scsi_execute_in_process_context);
Index: BUILD-2.6/drivers/scsi/scsi_scan.c
===================================================================
--- BUILD-2.6.orig/drivers/scsi/scsi_scan.c 2006-02-20 08:57:40.000000000 -0600
+++ BUILD-2.6/drivers/scsi/scsi_scan.c 2006-02-23 14:18:20.000000000 -0600
@@ -349,6 +349,8 @@
starget->channel = channel;
INIT_LIST_HEAD(&starget->siblings);
INIT_LIST_HEAD(&starget->devices);
+ starget->state = STARGET_RUNNING;
+ retry:
spin_lock_irqsave(shost->host_lock, flags);
found_target = __scsi_find_target(parent, channel, id);
@@ -381,8 +383,15 @@
found_target->reap_ref++;
spin_unlock_irqrestore(shost->host_lock, flags);
put_device(parent);
- kfree(starget);
- return found_target;
+ if (found_target->state != STARGET_DEL) {
+ kfree(starget);
+ return found_target;
+ }
+ /* Unfortunately, we found a dying target; need to
+ * wait until it's dead before we can get a new one */
+ put_device(&found_target->dev);
+ flush_scheduled_work();
+ goto retry;
}
static void scsi_target_reap_usercontext(void *data)
@@ -391,21 +400,13 @@
struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
unsigned long flags;
+ transport_remove_device(&starget->dev);
+ device_del(&starget->dev);
+ transport_destroy_device(&starget->dev);
spin_lock_irqsave(shost->host_lock, flags);
-
- if (--starget->reap_ref == 0 && list_empty(&starget->devices)) {
- list_del_init(&starget->siblings);
- spin_unlock_irqrestore(shost->host_lock, flags);
- transport_remove_device(&starget->dev);
- device_del(&starget->dev);
- transport_destroy_device(&starget->dev);
- put_device(&starget->dev);
- return;
-
- }
+ list_del_init(&starget->siblings);
spin_unlock_irqrestore(shost->host_lock, flags);
-
- return;
+ put_device(&starget->dev);
}
/**
@@ -419,7 +420,23 @@
*/
void scsi_target_reap(struct scsi_target *starget)
{
- scsi_execute_in_process_context(scsi_target_reap_usercontext, starget);
+ struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
+ unsigned long flags;
+
+ spin_lock_irqsave(shost->host_lock, flags);
+
+ if (--starget->reap_ref == 0 && list_empty(&starget->devices)) {
+ BUG_ON(starget->state == STARGET_DEL);
+ starget->state = STARGET_DEL;
+ spin_unlock_irqrestore(shost->host_lock, flags);
+ execute_in_process_context(scsi_target_reap_usercontext,
+ starget, &starget->ew);
+ return;
+
+ }
+ spin_unlock_irqrestore(shost->host_lock, flags);
+
+ return;
}
/**
Index: BUILD-2.6/drivers/scsi/scsi_sysfs.c
===================================================================
--- BUILD-2.6.orig/drivers/scsi/scsi_sysfs.c 2006-02-20 08:57:40.000000000 -0600
+++ BUILD-2.6/drivers/scsi/scsi_sysfs.c 2006-02-20 10:02:58.000000000 -0600
@@ -256,7 +256,9 @@
static void scsi_device_dev_release(struct device *dev)
{
- scsi_execute_in_process_context(scsi_device_dev_release_usercontext, dev);
+ struct scsi_device *sdp = to_scsi_device(dev);
+ execute_in_process_context(scsi_device_dev_release_usercontext, dev,
+ &sdp->ew);
}
static struct class sdev_class = {
Index: BUILD-2.6/include/scsi/scsi.h
===================================================================
--- BUILD-2.6.orig/include/scsi/scsi.h 2006-02-20 08:57:40.000000000 -0600
+++ BUILD-2.6/include/scsi/scsi.h 2006-02-20 10:02:58.000000000 -0600
@@ -433,6 +433,4 @@
/* Used to obtain the PCI location of a device */
#define SCSI_IOCTL_GET_PCI 0x5387
-int scsi_execute_in_process_context(void (*fn)(void *data), void *data);
-
#endif /* _SCSI_SCSI_H */
Index: BUILD-2.6/include/scsi/scsi_device.h
===================================================================
--- BUILD-2.6.orig/include/scsi/scsi_device.h 2006-02-20 08:57:40.000000000 -0600
+++ BUILD-2.6/include/scsi/scsi_device.h 2006-02-20 10:02:58.000000000 -0600
@@ -4,6 +4,7 @@
#include <linux/device.h>
#include <linux/list.h>
#include <linux/spinlock.h>
+#include <linux/workqueue.h>
#include <asm/atomic.h>
struct request_queue;
@@ -137,6 +138,8 @@
struct device sdev_gendev;
struct class_device sdev_classdev;
+ struct execute_work ew; /* used to get process context on put */
+
enum scsi_device_state sdev_state;
unsigned long sdev_data[0];
} __attribute__((aligned(sizeof(unsigned long))));
@@ -153,6 +156,11 @@
#define scmd_printk(prefix, scmd, fmt, a...) \
dev_printk(prefix, &(scmd)->device->sdev_gendev, fmt, ##a)
+enum scsi_target_state {
+ STARGET_RUNNING = 1,
+ STARGET_DEL,
+};
+
/*
* scsi_target: representation of a scsi target, for now, this is only
* used for single_lun devices. If no one has active IO to the target,
@@ -169,6 +177,8 @@
* scsi_device.id eventually */
unsigned long create:1; /* signal that it needs to be added */
char scsi_level;
+ struct execute_work ew;
+ enum scsi_target_state state;
void *hostdata; /* available to low-level driver */
unsigned long starget_data[0]; /* for the transport */
/* starget_data must be the last element!!!! */
-
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