Commit ffedb452 authored by James Bottomley's avatar James Bottomley Committed by James Bottomley

[SCSI] fix scsi process problems and clean up the target reap issues

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.
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent 1fa44eca
......@@ -2257,61 +2257,3 @@ scsi_target_unblock(struct device *dev)
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);
......@@ -349,6 +349,8 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
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 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
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 @@ static void scsi_target_reap_usercontext(void *data)
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 @@ static void scsi_target_reap_usercontext(void *data)
*/
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;
}
/**
......
......@@ -256,7 +256,9 @@ static void scsi_device_dev_release_usercontext(void *data)
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 = {
......
......@@ -433,6 +433,4 @@ struct scsi_lun {
/* 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 */
......@@ -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 scsi_device {
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 @@ struct scsi_device {
#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,
......@@ -172,6 +180,8 @@ struct scsi_target {
/* means no lun present */
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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