From: David Schleef <ds@schleef.org>
Date: Thu, 16 May 2002 22:10:53 +0000 (+0000)
Subject: Change pseudo-locking to spin locks.
X-Git-Tag: r0_7_65~39
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=7b252dc2d2356d3f93bb5358f65357755ecf6e15;p=comedi.git

Change pseudo-locking to spin locks.
---

diff --git a/comedi/comedi_fops.c b/comedi/comedi_fops.c
index 0cc81a90..9c8ed70b 100644
--- a/comedi/comedi_fops.c
+++ b/comedi/comedi_fops.c
@@ -54,6 +54,7 @@ MODULE_LICENSE("GPL");
 #endif
 
 comedi_device *comedi_devices;
+spinlock_t big_comedi_lock = SPIN_LOCK_UNLOCKED;
 
 static int do_devconfig_ioctl(comedi_device *dev,comedi_devconfig *arg,kdev_t minor);
 static int do_bufconfig_ioctl(comedi_device *dev,void *arg);
@@ -1010,26 +1011,12 @@ cleanup:
 	writes:
 		none
 
-	non-RT linux always controls rtcomedi_lock_semaphore.  If an
-	RT-linux process wants the lock, it first checks rtcomedi_lock_semaphore.
-	If it is 1, it knows it is pre-empting this function, and fails.
-	Obviously, if RT-linux fails to get a lock, it *must* allow
-	linux to run, since that is the only way to free the lock.
-
-	This function is not SMP compatible.
-
-	necessary locking:
-	- ioctl/rt lock  (this type)
-	- lock while subdevice busy
-	- lock while subdevice being programmed
-
 */
 
-volatile int rtcomedi_lock_semaphore=0;
-
 static int do_lock_ioctl(comedi_device *dev,unsigned int arg,void * file)
 {
 	int ret=0;
+	unsigned long flags;
 	comedi_subdevice *s;
 
 	if(arg>=dev->n_subdevices)
@@ -1039,7 +1026,7 @@ static int do_lock_ioctl(comedi_device *dev,unsigned int arg,void * file)
 	if(s->busy)
 		return -EBUSY;
 
-	rtcomedi_lock_semaphore=1;
+	comedi_spin_lock_irqsave(&big_comedi_lock, flags);
 
 	if(s->lock && s->lock!=file){
 		ret=-EACCES;
@@ -1047,7 +1034,7 @@ static int do_lock_ioctl(comedi_device *dev,unsigned int arg,void * file)
 		s->lock=file;
 	}
 
-	rtcomedi_lock_semaphore=0;
+	comedi_spin_unlock_irqrestore(&big_comedi_lock, flags);
 
 	if(ret<0)
 		return ret;
diff --git a/comedi/comedi_ksyms.c b/comedi/comedi_ksyms.c
index 1b269ca1..46681172 100644
--- a/comedi/comedi_ksyms.c
+++ b/comedi/comedi_ksyms.c
@@ -61,7 +61,7 @@ EXPORT_SYMBOL(rt_pend_call);
 
 /* for kcomedilib */
 EXPORT_SYMBOL(comedi_devices);
-EXPORT_SYMBOL(rtcomedi_lock_semaphore);
+EXPORT_SYMBOL(big_comedi_lock);
 EXPORT_SYMBOL(check_chanlist);
 
 #endif
diff --git a/comedi/kcomedilib/kcomedilib_main.c b/comedi/kcomedilib/kcomedilib_main.c
index 7043b032..b4615886 100644
--- a/comedi/kcomedilib/kcomedilib_main.c
+++ b/comedi/kcomedilib/kcomedilib_main.c
@@ -46,8 +46,6 @@ MODULE_DESCRIPTION("Comedi kernel library");
 MODULE_LICENSE("GPL");
 
 
-static spinlock_t lock_spinlock;
-
 
 comedi_t *comedi_open(const char *filename)
 {
@@ -238,7 +236,7 @@ int comedi_do_insn(comedi_t *d,comedi_insn *insn)
 			ret = -EBUSY;
 			goto error;
 		}
-		s->busy = (void *)&rtcomedi_lock_semaphore;
+		s->busy = d;
 
 		switch(insn->insn){
 			case INSN_READ:
@@ -297,7 +295,7 @@ int comedi_lock(comedi_t *d,unsigned int subdevice)
 	unsigned long flags;
 	int ret=0;
 
-	comedi_spin_lock_irqsave(&lock_spinlock,flags);
+	comedi_spin_lock_irqsave(&big_comedi_lock,flags);
 	
 	if(s->busy){
 		ret = -EBUSY;
@@ -306,11 +304,11 @@ int comedi_lock(comedi_t *d,unsigned int subdevice)
 			ret = -EACCES;
 		}else{
 			__MOD_INC_USE_COUNT(dev->driver->module);
-			s->lock=(void *)&rtcomedi_lock_semaphore;
+			s->lock = d;
 		}
 	}
 
-	comedi_spin_unlock_irqrestore(&lock_spinlock,flags);
+	comedi_spin_unlock_irqrestore(&big_comedi_lock,flags);
 	
 	return ret;
 }
@@ -339,15 +337,15 @@ int comedi_unlock(comedi_t *d,unsigned int subdevice)
 
 	async = s->async;
 
-	comedi_spin_lock_irqsave(&lock_spinlock,flags);
+	comedi_spin_lock_irqsave(&big_comedi_lock,flags);
 
 	if(s->busy){
-		comedi_spin_unlock_irqrestore(&lock_spinlock,flags);
+		comedi_spin_unlock_irqrestore(&big_comedi_lock,flags);
 		return -EBUSY;
 	}
 
 	if(s->lock && s->lock!=(void *)d){
-		comedi_spin_unlock_irqrestore(&lock_spinlock,flags);
+		comedi_spin_unlock_irqrestore(&big_comedi_lock,flags);
 		return -EACCES;
 	}
 
@@ -360,7 +358,7 @@ int comedi_unlock(comedi_t *d,unsigned int subdevice)
 	}
 	__MOD_DEC_USE_COUNT(dev->driver->module);
 
-	comedi_spin_unlock_irqrestore(&lock_spinlock,flags);
+	comedi_spin_unlock_irqrestore(&big_comedi_lock,flags);
 
 	return 0;
 }
diff --git a/include/linux/comedidev.h b/include/linux/comedidev.h
index 715db327..fae7dc43 100644
--- a/include/linux/comedidev.h
+++ b/include/linux/comedidev.h
@@ -214,6 +214,7 @@ struct comedi_device_struct{
 
 
 extern comedi_device *comedi_devices;
+extern spinlock_t big_comedi_lock;
 
 /*
  * function prototypes
@@ -270,8 +271,6 @@ static inline void comedi_proc_cleanup(void) {}
 int do_rangeinfo_ioctl(comedi_device *dev,comedi_rangeinfo *arg);
 int check_chanlist(comedi_subdevice *s,int n,unsigned int *chanlist);
 
-extern volatile int rtcomedi_lock_semaphore;
-
 /* range stuff */