-------- Forwarded Message --------
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>,
containers@xxxxxxxxxxxxxx, Oleg Nesterov <oleg@xxxxxxxxxx>, Christoph
Hellwig <hch@xxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, Darrick J.
Wong <djwong@xxxxxxxxxx>, James Bottomley <James.Bottomley@xxxxxxxxxxxx>
Subject: Re: [PATCH] sas_scsi_host: Convert to use the kthread API
Date: Sun, 22 Apr 2007 20:38:43 +0100
On Thu, Apr 19, 2007 at 05:37:53PM -0700, Andrew Morton wrote:
> On Thu, 19 Apr 2007 01:58:38 -0600
> "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> wrote:
>
> > From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> >
> > This patch modifies the sas scsi host thread startup
> > to use kthread_run not kernel_thread and deamonize.
> > kthread_run is slightly simpler and more maintainable.
> >
>
> Again, I'll rename this to "partially convert...". This driver should be
> using kthread_should_stop() and kthread_stop() rather than the
> apparently-unnecessary ->queue_thread_kill thing.
>
> This driver was merged two and a half years after the kthread API was
> available. Our coding-vs-reviewing effort is out of balance.
Here's a full conversion.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Index: linux-2.6/drivers/scsi/libsas/sas_scsi_host.c
===================================================================
--- linux-2.6.orig/drivers/scsi/libsas/sas_scsi_host.c 2007-04-22 20:30:39.000000000 +0200
+++ linux-2.6/drivers/scsi/libsas/sas_scsi_host.c 2007-04-22 20:36:51.000000000 +0200
@@ -23,6 +23,8 @@
*
*/
+#include <linux/kthread.h>
+
#include "sas_internal.h"
#include <scsi/scsi_host.h>
@@ -184,7 +186,7 @@ static int sas_queue_up(struct sas_task
list_add_tail(&task->list, &core->task_queue);
core->task_queue_size += 1;
spin_unlock_irqrestore(&core->task_queue_lock, flags);
- up(&core->queue_thread_sema);
+ wake_up_process(core->queue_thread);
return 0;
}
@@ -819,7 +821,7 @@ static void sas_queue(struct sas_ha_stru
struct sas_internal *i = to_sas_internal(core->shost->transportt);
spin_lock_irqsave(&core->task_queue_lock, flags);
- while (!core->queue_thread_kill &&
+ while (!kthread_should_stop() &&
!list_empty(&core->task_queue)) {
can_queue = sas_ha->lldd_queue_size - core->task_queue_size;
@@ -858,8 +860,6 @@ static void sas_queue(struct sas_ha_stru
spin_unlock_irqrestore(&core->task_queue_lock, flags);
}
-static DECLARE_COMPLETION(queue_th_comp);
-
/**
* sas_queue_thread -- The Task Collector thread
* @_sas_ha: pointer to struct sas_ha
@@ -867,40 +867,33 @@ static DECLARE_COMPLETION(queue_th_comp)
static int sas_queue_thread(void *_sas_ha)
{
struct sas_ha_struct *sas_ha = _sas_ha;
- struct scsi_core *core = &sas_ha->core;
- daemonize("sas_queue_%d", core->shost->host_no);
current->flags |= PF_NOFREEZE;
- complete(&queue_th_comp);
-
while (1) {
- down_interruptible(&core->queue_thread_sema);
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule();
sas_queue(sas_ha);
- if (core->queue_thread_kill)
+ if (kthread_should_stop())
break;
}
- complete(&queue_th_comp);
-
return 0;
}
int sas_init_queue(struct sas_ha_struct *sas_ha)
{
- int res;
struct scsi_core *core = &sas_ha->core;
spin_lock_init(&core->task_queue_lock);
core->task_queue_size = 0;
INIT_LIST_HEAD(&core->task_queue);
- init_MUTEX_LOCKED(&core->queue_thread_sema);
- res = kernel_thread(sas_queue_thread, sas_ha, 0);
- if (res >= 0)
- wait_for_completion(&queue_th_comp);
-
- return res < 0 ? res : 0;
+ core->queue_thread = kthread_run(sas_queue_thread, sas_ha,
+ "sas_queue_%d", core->shost->host_no);
+ if (IS_ERR(core->queue_thread))
+ return PTR_ERR(core->queue_thread);
+ return 0;
}
void sas_shutdown_queue(struct sas_ha_struct *sas_ha)
@@ -909,10 +902,7 @@ void sas_shutdown_queue(struct sas_ha_st
struct scsi_core *core = &sas_ha->core;
struct sas_task *task, *n;
- init_completion(&queue_th_comp);
- core->queue_thread_kill = 1;
- up(&core->queue_thread_sema);
- wait_for_completion(&queue_th_comp);
+ kthread_stop(core->queue_thread);
if (!list_empty(&core->task_queue))
SAS_DPRINTK("HA: %llx: scsi core task queue is NOT empty!?\n",
Index: linux-2.6/include/scsi/libsas.h
===================================================================
--- linux-2.6.orig/include/scsi/libsas.h 2007-04-22 20:32:41.000000000 +0200
+++ linux-2.6/include/scsi/libsas.h 2007-04-22 20:32:59.000000000 +0200
@@ -314,8 +314,7 @@ struct scsi_core {
struct list_head task_queue;
int task_queue_size;
- struct semaphore queue_thread_sema;
- int queue_thread_kill;
+ struct task_struct *queue_thread;
};
struct sas_ha_event {
-
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