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* [PATCH] add execute_in_process_context() API
@ 2006-02-07 20:00 James Bottomley
  2006-02-07 20:08 ` [SCSI] fix wrong context bugs in SCSI James Bottomley
                   ` (2 more replies)
  0 siblings, 3 replies; 12+ messages in thread
From: James Bottomley @ 2006-02-07 20:00 UTC (permalink / raw)
  To: linux-kernel, linux-scsi, Andrew Morton

SCSI needs this for our scheme to avoid executing generic device release
calls from interrupt context (SCSI patch using this to follow).

If no-one objects, I'd like to slide this into the scsi-rc-fixes-2.6
tree for 2.6.16.

James

--

[PATCH] add execute_in_process_context() API

We have several points in the SCSI stack (primarily for our device
functions) where we need to guarantee process context, but (given the
place where the last reference was released) we cannot guarantee this.

This API gets around the issue by executing the function directly if
the caller has process context, but scheduling a workqueue to execute
in process context if the caller doesn't have it.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

Index: BUILD-2.6/include/linux/workqueue.h
===================================================================
--- BUILD-2.6.orig/include/linux/workqueue.h	2006-02-07 09:22:30.000000000 -0600
+++ BUILD-2.6/include/linux/workqueue.h	2006-02-07 10:22:29.000000000 -0600
@@ -74,6 +74,7 @@
 void cancel_rearming_delayed_work(struct work_struct *work);
 void cancel_rearming_delayed_workqueue(struct workqueue_struct *,
 				       struct work_struct *);
+int execute_in_process_context(void (*fn)(void *), void *);
 
 /*
  * Kill off a pending schedule_delayed_work().  Note that the work callback
Index: BUILD-2.6/kernel/workqueue.c
===================================================================
--- BUILD-2.6.orig/kernel/workqueue.c	2006-02-07 09:22:30.000000000 -0600
+++ BUILD-2.6/kernel/workqueue.c	2006-02-07 11:07:47.000000000 -0600
@@ -27,6 +27,7 @@
 #include <linux/cpu.h>
 #include <linux/notifier.h>
 #include <linux/kthread.h>
+#include <linux/hardirq.h>
 
 /*
  * The per-CPU workqueue (if single thread, we always use the first
@@ -476,6 +477,63 @@
 }
 EXPORT_SYMBOL(cancel_rearming_delayed_work);
 
+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);
+}
+
+/**
+ * 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 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(execute_in_process_context);
+
 int keventd_up(void)
 {
 	return keventd_wq != NULL;

^ permalink raw reply	[flat|nested] 12+ messages in thread
end of thread, other threads:[~2006-02-14 16:48 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-02-07 20:00 [PATCH] add execute_in_process_context() API James Bottomley
2006-02-07 20:08 ` [SCSI] fix wrong context bugs in SCSI James Bottomley
2006-02-07 22:05   ` Brian King
2006-02-07 23:26     ` James Bottomley
2006-02-08  8:56   ` Jens Axboe
2006-02-08 15:31     ` James Bottomley
2006-02-08 15:52       ` Jens Axboe
2006-02-14 16:42         ` James Bottomley
2006-02-14 16:48           ` James Bottomley
2006-02-07 20:26 ` [PATCH] add execute_in_process_context() API Dave Jones
2006-02-07 20:34   ` Andrew Morton
2006-02-08 12:51 ` Stefan Richter

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