If the unmap thread has passed the find_free_blocks call
but has not yet hit the prepare_to_wait we will miss
any tcmu_irqcontrol wake_up calls. This patch replaces
the our kthread use with a work_struct which will handle
this for us and allow use to remove the race checks for
the time out and queueing wake up calls.
Signed-off-by: Mike Christie <mchristi@xxxxxxxxxx>
---
drivers/target/target_core_user.c | 72 +++++++--------------------------------
1 file changed, 12 insertions(+), 60 deletions(-)
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 6f9646e..fc82df6 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -32,7 +32,7 @@
#include <linux/highmem.h>
#include <linux/configfs.h>
#include <linux/mutex.h>
-#include <linux/kthread.h>
+#include <linux/workqueue.h>
#include <net/genetlink.h>
#include <scsi/scsi_common.h>
#include <scsi/scsi_proto.h>
@@ -179,9 +179,6 @@ struct tcmu_cmd {
unsigned long flags;
};
-static struct task_struct *unmap_thread;
-static wait_queue_head_t unmap_wait;
-
static DEFINE_SPINLOCK(timed_out_udevs_lock);
static LIST_HEAD(timed_out_udevs);
@@ -203,6 +200,7 @@ static DEFINE_SPINLOCK(root_udev_waiter_lock);
static LIST_HEAD(root_udev_waiter);
static atomic_t global_db_count = ATOMIC_INIT(0);
+struct work_struct tcmu_unmap_work;
static struct kmem_cache *tcmu_cmd_cache;
@@ -822,7 +820,7 @@ static int add_to_cmdr_queue(struct tcmu_cmd *tcmu_cmd)
pr_debug("adding %s to block waiter list\n", udev->name);
list_add_tail(&udev->waiter, &root_udev_waiter);
- wake_up(&unmap_wait);
+ schedule_work(&tcmu_unmap_work);
}
spin_unlock(&root_udev_waiter_lock);
return 0;
@@ -1165,7 +1163,7 @@ static void tcmu_device_timedout(unsigned long data)
list_add_tail(&udev->timedout_entry, &timed_out_udevs);
spin_unlock(&timed_out_udevs_lock);
- wake_up(&unmap_wait);
+ schedule_work(&tcmu_unmap_work);
}
static int tcmu_attach_hba(struct se_hba *hba, u32 host_id)
@@ -1284,7 +1282,7 @@ static int tcmu_irqcontrol(struct uio_info *info, s32 irq_on)
* of it.
*/
if (!list_empty(&tcmu_dev->waiter)) {
- wake_up(&unmap_wait);
+ schedule_work(&tcmu_unmap_work);
} else {
tcmu_handle_completions(tcmu_dev);
run_cmdr_queue(tcmu_dev);
@@ -2296,50 +2294,11 @@ static void check_timedout_devices(void)
spin_unlock_bh(&timed_out_udevs_lock);
}
-static int unmap_thread_fn(void *data)
+static void tcmu_unmap_work_fn(struct work_struct *work)
{
- bool drained = true;
- bool has_block_waiters;
- bool has_timed_out_devs;
-
- while (!kthread_should_stop()) {
- DEFINE_WAIT(__wait);
-
- prepare_to_wait(&unmap_wait, &__wait, TASK_INTERRUPTIBLE);
- /*
- * If we had space left, check if devs were added/readded
- * while the lock was dropped.
- */
- spin_lock(&root_udev_waiter_lock);
- has_block_waiters = true;
- if (list_empty(&root_udev_waiter))
- has_block_waiters = false;
- spin_unlock(&root_udev_waiter_lock);
-
- spin_lock_bh(&timed_out_udevs_lock);
- has_timed_out_devs = true;
- if (list_empty(&timed_out_udevs))
- has_timed_out_devs = false;
- spin_unlock_bh(&timed_out_udevs_lock);
-
- /*
- * Handle race where new waiters were added and we still
- * had space (were at least able to drain the queue on
- * the previous run).
- */
- if ((!drained || !has_block_waiters) && !has_timed_out_devs)
- schedule();
-
- finish_wait(&unmap_wait, &__wait);
-
- check_timedout_devices();
-
- find_free_blocks();
-
- drained = run_cmdr_queues();
- }
-
- return 0;
+ check_timedout_devices();
+ find_free_blocks();
+ run_cmdr_queues();
}
static int __init tcmu_module_init(void)
@@ -2348,6 +2307,8 @@ static int __init tcmu_module_init(void)
BUILD_BUG_ON((sizeof(struct tcmu_cmd_entry) % TCMU_OP_ALIGN_SIZE) != 0);
+ INIT_WORK(&tcmu_unmap_work, tcmu_unmap_work_fn);
+
tcmu_cmd_cache = kmem_cache_create("tcmu_cmd_cache",
sizeof(struct tcmu_cmd),
__alignof__(struct tcmu_cmd),
@@ -2393,17 +2354,8 @@ static int __init tcmu_module_init(void)
if (ret)
goto out_attrs;
- init_waitqueue_head(&unmap_wait);
- unmap_thread = kthread_run(unmap_thread_fn, NULL, "tcmu_unmap");
- if (IS_ERR(unmap_thread)) {
- ret = PTR_ERR(unmap_thread);
- goto out_unreg_transport;
- }
-
return 0;
-out_unreg_transport:
- target_backend_unregister(&tcmu_ops);
out_attrs:
kfree(tcmu_attrs);
out_unreg_genl:
@@ -2418,7 +2370,7 @@ static int __init tcmu_module_init(void)
static void __exit tcmu_module_exit(void)
{
- kthread_stop(unmap_thread);
+ cancel_work_sync(&tcmu_unmap_work);
target_backend_unregister(&tcmu_ops);
kfree(tcmu_attrs);
genl_unregister_family(&tcmu_genl_family);
--
2.7.2
--
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