[KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[irwan.djajadi]

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drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
wait_event_interruptible()

Signed-off-by: Irwan Djajadi <irwan.djajadi@iname.com>

diff -pruNX 2.6.14-rc5/Documentation/dontdiff 2.6.14-rc5/drivers/block/acsi_slm.c mod/drivers/block/acsi_slm.c
--- 2.6.14-rc5/drivers/block/acsi_slm.c	2005-10-22 00:06:17.000000000 -0500
+++ mod/drivers/block/acsi_slm.c	2005-10-22 15:10:39.000000000 -0500
@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
 
 	while( SLMState == PRINTING ||
 		   (SLMState == FILLING && SLMBufOwner != device) ) {
-		interruptible_sleep_on( &slm_wait );
+		wait_event_interruptible( slm_wait, SLMState==IDLE );
 		if (signal_pending(current))
 			return( -ERESTARTSYS );
 	}
 



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[KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/swim3.c: replace

[irwan.djajadi]

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drivers/block/swim3.c: replace interruptible_sleep_on() with
wait_event_interruptible()

Signed-off-by: Irwan Djajadi <irwan.djajadi@iname.com>

diff -pruNX 2.6.14-rc5/Documentation/dontdiff 2.6.14-rc5/drivers/block/swim3.c mod/drivers/block/swim3.c
--- 2.6.14-rc5/drivers/block/swim3.c	2005-10-22 00:06:17.000000000 -0500
+++ mod/drivers/block/swim3.c	2005-10-22 15:31:52.000000000 -0500
@@ -800,7 +800,7 @@ static int grab_drive(struct floppy_stat
 				restore_flags(flags);
 				return -EINTR;
 			}
-			interruptible_sleep_on(&fs->wait);
+			wait_event_interruptible(fs->wait, fs->state == available);
 		}
 		--fs->wanted;
 	}
 



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[KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/swim_iop.c: replace

[irwan.djajadi]

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drivers/block/swim_iop.c: replace interruptible_sleep_on() with
wait_event_interruptible()

Signed-off-by: Irwan Djajadi <irwan.djajadi@iname.com>

diff -pruNX 2.6.14-rc5/Documentation/dontdiff 2.6.14-rc5/drivers/block/swim_iop.c mod/drivers/block/swim_iop.c
--- 2.6.14-rc5/drivers/block/swim_iop.c	2005-10-22 00:06:17.000000000 -0500
+++ mod/drivers/block/swim_iop.c	2005-10-22 15:33:26.000000000 -0500
@@ -436,7 +436,7 @@ static int grab_drive(struct floppy_stat
 				local_irq_restore(flags);
 				return -EINTR;
 			}
-			interruptible_sleep_on(&fs->wait);
+			wait_event_interruptible(fs->wait, fs->state == available);
 		}
 		--fs->wanted;
 	}
 



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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Alexey Dobriyan]

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On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com wrote:
> drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
> wait_event_interruptible()

> --- 2.6.14-rc5/drivers/block/acsi_slm.c
> +++ mod/drivers/block/acsi_slm.c
> @@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
>  
>  	while( SLMState == PRINTING ||
>  		   (SLMState == FILLING && SLMBufOwner != device) ) {
> -		interruptible_sleep_on( &slm_wait );
> +		wait_event_interruptible( slm_wait, SLMState==IDLE );
>  		if (signal_pending(current))
>  			return( -ERESTARTSYS );
>  	}

acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
from -kj looks more correct.

From: Nishanth Aravamudan

Use wait_event_interruptible() instead of the deprecated
interruptible_sleep_on(). The sleep_on() call later in the same
function is replaced with inline wait-queue code which achieves the
same. This required adding a local wait-queue, though.

--- a/drivers/block/acsi_slm.c
+++ b/drivers/block/acsi_slm.c
@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
 	int		device = iminor(node);
 	int		n, filled, w, h;
 
-	while( SLMState == PRINTING ||
-		   (SLMState == FILLING && SLMBufOwner != device) ) {
-		interruptible_sleep_on( &slm_wait );
-		if (signal_pending(current))
-			return( -ERESTARTSYS );
-	}
+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
+				(SLMState != FILLING || SLMBufOwner == device)));
+	if (signal_pending(current))
+		return -ERESTARTSYS;
 	if (SLMState == IDLE) {
 		/* first data of page: get current page size  */
 		if (slm_get_pagesize( device, &w, &h ))


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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/swim3.c: replace

[Alexey Dobriyan]

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On Sat, Oct 22, 2005 at 09:55:25PM -0500, irwan.djajadi@iname.com wrote:
> --- 2.6.14-rc5/drivers/block/swim3.c
> +++ mod/drivers/block/swim3.c
> @@ -800,7 +800,7 @@ static int grab_drive(struct floppy_stat

        save_flags(flags);
	cli();
	if (fs->state != idle) {
		++fs->wanted;
		while (fs->state != available) {
			if (interruptible && signal_pending(current)) {
>  				restore_flags(flags);
>  				return -EINTR;
>  			}
> -			interruptible_sleep_on(&fs->wait);
> +			wait_event_interruptible(fs->wait, fs->state == available);

Correct me if I'm wrong, but level of bugginess remains the same:
scheduling with interrupts disabled.

>  		}
>  		--fs->wanted;
>  	}


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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/swim_iop.c: replace

[Alexey Dobriyan]

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On Sat, Oct 22, 2005 at 09:56:31PM -0500, irwan.djajadi@iname.com wrote:
> --- 2.6.14-rc5/drivers/block/swim_iop.c
> +++ mod/drivers/block/swim_iop.c
> @@ -436,7 +436,7 @@ static int grab_drive(struct floppy_stat
>  				local_irq_restore(flags);
>  				return -EINTR;
>  			}
> -			interruptible_sleep_on(&fs->wait);
> +			wait_event_interruptible(fs->wait, fs->state == available);
>  		}
>  		--fs->wanted;
>  	}

Ditto. local_irq_save().


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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Irwan Djajadi]

Alexey Dobriyan wrote:

>On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com wrote:
>  
>
>>drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
>>wait_event_interruptible()
>>    
>>
>
>  
>
>>--- 2.6.14-rc5/drivers/block/acsi_slm.c
>>+++ mod/drivers/block/acsi_slm.c
>>@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
>> 
>> 	while( SLMState = PRINTING ||
>> 		   (SLMState = FILLING && SLMBufOwner != device) ) {
>>-		interruptible_sleep_on( &slm_wait );
>>+		wait_event_interruptible( slm_wait, SLMState=IDLE );
>> 		if (signal_pending(current))
>> 			return( -ERESTARTSYS );
>> 	}
>>    
>>
>
>acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
>from -kj looks more correct.
>
>From: Nishanth Aravamudan
>
>Use wait_event_interruptible() instead of the deprecated
>interruptible_sleep_on(). The sleep_on() call later in the same
>function is replaced with inline wait-queue code which achieves the
>same. This required adding a local wait-queue, though.
>
>--- a/drivers/block/acsi_slm.c
>+++ b/drivers/block/acsi_slm.c
>@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
> 	int		device = iminor(node);
> 	int		n, filled, w, h;
> 
>-	while( SLMState = PRINTING ||
>-		   (SLMState = FILLING && SLMBufOwner != device) ) {
>-		interruptible_sleep_on( &slm_wait );
>-		if (signal_pending(current))
>-			return( -ERESTARTSYS );
>-	}
>+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
>+				(SLMState != FILLING || SLMBufOwner = device)));
>+	if (signal_pending(current))
>+		return -ERESTARTSYS;
> 	if (SLMState = IDLE) {
> 		/* first data of page: get current page size  */
> 		if (slm_get_pagesize( device, &w, &h ))
>
>  
>
That does look more correct. Please ignore my patch.
Thanks!
--
Irwan
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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/swim3.c: replace

[irwan.djajadi]

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On Tue, Oct 25, 2005 at 01:23:20AM +0400, Alexey Dobriyan wrote:
> On Sat, Oct 22, 2005 at 09:55:25PM -0500, irwan.djajadi@iname.com wrote:
> > --- 2.6.14-rc5/drivers/block/swim3.c
> > +++ mod/drivers/block/swim3.c
> > @@ -800,7 +800,7 @@ static int grab_drive(struct floppy_stat
> 
>         save_flags(flags);
> 	cli();
> 	if (fs->state != idle) {
> 		++fs->wanted;
> 		while (fs->state != available) {
> 			if (interruptible && signal_pending(current)) {
> >  				restore_flags(flags);
> >  				return -EINTR;
> >  			}
> > -			interruptible_sleep_on(&fs->wait);
> > +			wait_event_interruptible(fs->wait, fs->state == available);
> 
> Correct me if I'm wrong, but level of bugginess remains the same:
> scheduling with interrupts disabled.
> 
> >  		}
> >  		--fs->wanted;
> >  	}
> 

Nope, you're right.. Thanks for catching that.. I didn't think you can sleep
while interrupt is disabled.. Wouldn't the kernel BUG_ON() that ?

Anyway, here's my next try. A word of warning though, I don't have PPC machine
here, so I can't even compile this change. Please let me know if there's
anymore problem with this.

Thanks
--
Irwan


Fix interruptible_sleep_on() with wait_event_interruptible() or wait_event(),
and fix waiting while interrupt is disabled.

Signed-off-by: Irwan Djajadi <irwan.djajadi@iname.com>

diff -pruNX 2.6.14-rc5/Documentation/dontdiff 2.6.14-rc5/drivers/block/swim3.c mod/drivers/block/swim3.c
--- 2.6.14-rc5/drivers/block/swim3.c	2005-10-22 00:06:17.000000000 -0500
+++ mod/drivers/block/swim3.c	2005-10-24 21:32:44.000000000 -0500
@@ -789,24 +789,29 @@ static int grab_drive(struct floppy_stat
 		      int interruptible)
 {
 	unsigned long flags;
+	int err = 0;
 
 	save_flags(flags);
 	cli();
-	if (fs->state != idle) {
+	while ((fs->state != idle) && !err) {
 		++fs->wanted;
-		while (fs->state != available) {
-			if (interruptible && signal_pending(current)) {
-				--fs->wanted;
-				restore_flags(flags);
-				return -EINTR;
-			}
-			interruptible_sleep_on(&fs->wait);
+		restore_flags(flags);
+		if (interruptible) {
+			err = wait_event_interruptible(fs->wait,
+				fs->state == available);
+			if (err)
+				err = -EINTR;
+		} else {
+			wait_event(fs->wait, fs->state == available);
 		}
+		save_flags(flags);
+		cli();
 		--fs->wanted;
 	}
-	fs->state = state;
+	if (!err)
+		fs->state = state;
 	restore_flags(flags);
-	return 0;
+	return err;
 }
 
 static void release_drive(struct floppy_state *fs)

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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/swim_iop.c: replace

[irwan.djajadi]

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On Tue, Oct 25, 2005 at 01:25:21AM +0400, Alexey Dobriyan wrote:
> On Sat, Oct 22, 2005 at 09:56:31PM -0500, irwan.djajadi@iname.com wrote:
> > --- 2.6.14-rc5/drivers/block/swim_iop.c
> > +++ mod/drivers/block/swim_iop.c
> > @@ -436,7 +436,7 @@ static int grab_drive(struct floppy_stat
> >  				local_irq_restore(flags);
> >  				return -EINTR;
> >  			}
> > -			interruptible_sleep_on(&fs->wait);
> > +			wait_event_interruptible(fs->wait, fs->state == available);
> >  		}
> >  		--fs->wanted;
> >  	}
> 
> Ditto. local_irq_save().
> 

Yup, ditto as well.. :-)

Here's my next try. Thanks man
--
Irwan



Fix interruptible_sleep_on() with wait_event_interruptible() or wait_event(),
and fix waiting while interrupt is disabled.

Signed-off-by: Irwan Djajadi <irwan.djajadi@iname.com>

diff -pruNX 2.6.14-rc5/Documentation/dontdiff 2.6.14-rc5/drivers/block/swim_iop.c mod/drivers/block/swim_iop.c
--- 2.6.14-rc5/drivers/block/swim_iop.c	2005-10-22 00:06:17.000000000 -0500
+++ mod/drivers/block/swim_iop.c	2005-10-24 22:01:34.000000000 -0500
@@ -426,23 +426,27 @@ static int grab_drive(struct floppy_stat
 		      int interruptible)
 {
 	unsigned long flags;
+	int err = 0;
 
 	local_irq_save(flags);
-	if (fs->state != idle) {
+	while ((fs->state != idle) && !err) {
 		++fs->wanted;
-		while (fs->state != available) {
-			if (interruptible && signal_pending(current)) {
-				--fs->wanted;
-				local_irq_restore(flags);
-				return -EINTR;
-			}
-			interruptible_sleep_on(&fs->wait);
+		local_irq_restore(flags);
+		if (interruptible) {
+			err = wait_event_interruptible(fs->wait,
+				fs->state == available);
+			if (err)
+				err = -EINTR;
+		} else {
+			wait_event(fs->wait, fs->state == available);
 		}
+		local_irq_save(flags);
 		--fs->wanted;
 	}
-	fs->state = state;
+	if (!err)
+		fs->state = state;
 	local_irq_restore(flags);
-	return 0;
+	return err;
 }
 
 static void release_drive(struct floppy_state *fs)

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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Nishanth Aravamudan]

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On 24.10.2005 [18:46:01 -0500], Irwan Djajadi wrote:
> Alexey Dobriyan wrote:
> 
> >On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com wrote:
> > 
> >
> >>drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
> >>wait_event_interruptible()
> >>   
> >>
> >
> > 
> >
> >>--- 2.6.14-rc5/drivers/block/acsi_slm.c
> >>+++ mod/drivers/block/acsi_slm.c
> >>@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
> >>
> >>	while( SLMState == PRINTING ||
> >>		   (SLMState == FILLING && SLMBufOwner != device) ) {
> >>-		interruptible_sleep_on( &slm_wait );
> >>+		wait_event_interruptible( slm_wait, SLMState==IDLE );
> >>		if (signal_pending(current))
> >>			return( -ERESTARTSYS );
> >>	}
> >>   
> >>
> >
> >acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
> >from -kj looks more correct.
> >
> >From: Nishanth Aravamudan
> >
> >Use wait_event_interruptible() instead of the deprecated
> >interruptible_sleep_on(). The sleep_on() call later in the same
> >function is replaced with inline wait-queue code which achieves the
> >same. This required adding a local wait-queue, though.
> >
> >--- a/drivers/block/acsi_slm.c
> >+++ b/drivers/block/acsi_slm.c
> >@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
> >	int		device = iminor(node);
> >	int		n, filled, w, h;
> >
> >-	while( SLMState == PRINTING ||
> >-		   (SLMState == FILLING && SLMBufOwner != device) ) {
> >-		interruptible_sleep_on( &slm_wait );
> >-		if (signal_pending(current))
> >-			return( -ERESTARTSYS );
> >-	}
> >+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
> >+				(SLMState != FILLING || SLMBufOwner == 
> >device)));
> >+	if (signal_pending(current))
> >+		return -ERESTARTSYS;
> >	if (SLMState == IDLE) {
> >		/* first data of page: get current page size  */
> >		if (slm_get_pagesize( device, &w, &h ))
> >
> > 
> >
> That does look more correct. Please ignore my patch.
> Thanks!

@Irwan:

Have you tested any of the patches you are sending? I stopped replacing
the *sleep_on*() family of functions once I was outside of the domain of
trivial substitution.

You can't simply s/interruptible_sleep_on/wait_event_interruptible/ as
in many places the sleep_on() caller is not a loop, but one-time sleep!
I have noticed at least one case of this in the patches you are sending
out, but will try to make a more complete analysis soon.

@Alexey:

Be very careful pulling in these patches. I don't think any of the
remaining *sleep_on*() replacements are easy or trivial (at least the
ones w/o patches already in -KJ). I'll try to take a look more in depth
soon.

Thanks,
Nish

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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Irwan Djajadi]

Nishanth Aravamudan wrote:
> On 24.10.2005 [18:46:01 -0500], Irwan Djajadi wrote:
> 
>>Alexey Dobriyan wrote:
>>
>>
>>>On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com wrote:
>>>
>>>
>>>
>>>>drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
>>>>wait_event_interruptible()
>>>>  
>>>>
>>>
>>>
>>>
>>>>--- 2.6.14-rc5/drivers/block/acsi_slm.c
>>>>+++ mod/drivers/block/acsi_slm.c
>>>>@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
>>>>
>>>>	while( SLMState = PRINTING ||
>>>>		   (SLMState = FILLING && SLMBufOwner != device) ) {
>>>>-		interruptible_sleep_on( &slm_wait );
>>>>+		wait_event_interruptible( slm_wait, SLMState=IDLE );
>>>>		if (signal_pending(current))
>>>>			return( -ERESTARTSYS );
>>>>	}
>>>>  
>>>>
>>>
>>>acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
>>
>>>from -kj looks more correct.
>>
>>>From: Nishanth Aravamudan
>>>
>>>Use wait_event_interruptible() instead of the deprecated
>>>interruptible_sleep_on(). The sleep_on() call later in the same
>>>function is replaced with inline wait-queue code which achieves the
>>>same. This required adding a local wait-queue, though.
>>>
>>>--- a/drivers/block/acsi_slm.c
>>>+++ b/drivers/block/acsi_slm.c
>>>@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
>>>	int		device = iminor(node);
>>>	int		n, filled, w, h;
>>>
>>>-	while( SLMState = PRINTING ||
>>>-		   (SLMState = FILLING && SLMBufOwner != device) ) {
>>>-		interruptible_sleep_on( &slm_wait );
>>>-		if (signal_pending(current))
>>>-			return( -ERESTARTSYS );
>>>-	}
>>>+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
>>>+				(SLMState != FILLING || SLMBufOwner = 
>>>device)));
>>>+	if (signal_pending(current))
>>>+		return -ERESTARTSYS;
>>>	if (SLMState = IDLE) {
>>>		/* first data of page: get current page size  */
>>>		if (slm_get_pagesize( device, &w, &h ))
>>>
>>>
>>>
>>
>>That does look more correct. Please ignore my patch.
>>Thanks!
> 
> 
> @Irwan:
> 
> Have you tested any of the patches you are sending? I stopped replacing
> the *sleep_on*() family of functions once I was outside of the domain of
> trivial substitution.
> 
> You can't simply s/interruptible_sleep_on/wait_event_interruptible/ as
> in many places the sleep_on() caller is not a loop, but one-time sleep!
> I have noticed at least one case of this in the patches you are sending
> out, but will try to make a more complete analysis soon.
> 
> @Alexey:
> 
> Be very careful pulling in these patches. I don't think any of the
> remaining *sleep_on*() replacements are easy or trivial (at least the
> ones w/o patches already in -KJ). I'll try to take a look more in depth
> soon.
> 
> Thanks,
> Nish
> 

Hi Nish,

I only compile-test most of my patch over the weekend.. There are some 
that I didn't even do compile test on because it's for a different 
platform (I'm on x86). But yes, I am aware that some of *sleep_on*() 
family function fixes are not trivial. I only changed ones that I 
thought trivial. When the end-wait-condition is not clear to me, I left 
it alone, and I went to the next.

Maybe I'm missing something here, but I don't really see why 
interruptible_sleep_on() or wait_event_interruptible() is not a straight 
substitution when the caller is not in a loop..

interruptible_sleep_on() does not have a loop inside, and it's a single 
incantation of wait. When it wakes up, it could be because of a signal 
or end-condition.

I see that wait_event_interruptible() has a check outside and a loop 
inside to ensure that when it returns it's because of a signal or 
end-condition. (So it's a more correct version of interruptible_sleep_on())

The semantic looks the same to me, so why can't it be a straight 
substitution when the end-wait-condition is straightforward?

I don't intend to inject bugs, so I appreciate y'all's review of my 
patches, and let me know/smack me when I do dumb things.

Thanks!
--
Irwan
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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Nishanth Aravamudan]

[-- Attachment #1: Type: text/plain, Size: 5339 bytes --]

On 25.10.2005 [21:44:09 -0500], Irwan Djajadi wrote:
> Nishanth Aravamudan wrote:
> >On 24.10.2005 [18:46:01 -0500], Irwan Djajadi wrote:
> >
> >>Alexey Dobriyan wrote:
> >>
> >>
> >>>On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com wrote:
> >>>
> >>>
> >>>
> >>>>drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
> >>>>wait_event_interruptible()
> >>>> 
> >>>>
> >>>
> >>>
> >>>
> >>>>--- 2.6.14-rc5/drivers/block/acsi_slm.c
> >>>>+++ mod/drivers/block/acsi_slm.c
> >>>>@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
> >>>>
> >>>>	while( SLMState == PRINTING ||
> >>>>		   (SLMState == FILLING && SLMBufOwner != device) ) {
> >>>>-		interruptible_sleep_on( &slm_wait );
> >>>>+		wait_event_interruptible( slm_wait, SLMState==IDLE );
> >>>>		if (signal_pending(current))
> >>>>			return( -ERESTARTSYS );
> >>>>	}
> >>>> 
> >>>>
> >>>
> >>>acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
> >>
> >>>from -kj looks more correct.
> >>
> >>>From: Nishanth Aravamudan
> >>>
> >>>Use wait_event_interruptible() instead of the deprecated
> >>>interruptible_sleep_on(). The sleep_on() call later in the same
> >>>function is replaced with inline wait-queue code which achieves the
> >>>same. This required adding a local wait-queue, though.
> >>>
> >>>--- a/drivers/block/acsi_slm.c
> >>>+++ b/drivers/block/acsi_slm.c
> >>>@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
> >>>	int		device = iminor(node);
> >>>	int		n, filled, w, h;
> >>>
> >>>-	while( SLMState == PRINTING ||
> >>>-		   (SLMState == FILLING && SLMBufOwner != device) ) {
> >>>-		interruptible_sleep_on( &slm_wait );
> >>>-		if (signal_pending(current))
> >>>-			return( -ERESTARTSYS );
> >>>-	}
> >>>+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
> >>>+				(SLMState != FILLING || SLMBufOwner == 
> >>>device)));
> >>>+	if (signal_pending(current))
> >>>+		return -ERESTARTSYS;
> >>>	if (SLMState == IDLE) {
> >>>		/* first data of page: get current page size  */
> >>>		if (slm_get_pagesize( device, &w, &h ))
> >>>
> >>>
> >>>
> >>
> >>That does look more correct. Please ignore my patch.
> >>Thanks!
> >
> >
> >@Irwan:
> >
> >Have you tested any of the patches you are sending? I stopped replacing
> >the *sleep_on*() family of functions once I was outside of the domain of
> >trivial substitution.
> >
> >You can't simply s/interruptible_sleep_on/wait_event_interruptible/ as
> >in many places the sleep_on() caller is not a loop, but one-time sleep!
> >I have noticed at least one case of this in the patches you are sending
> >out, but will try to make a more complete analysis soon.
> >
> >@Alexey:
> >
> >Be very careful pulling in these patches. I don't think any of the
> >remaining *sleep_on*() replacements are easy or trivial (at least the
> >ones w/o patches already in -KJ). I'll try to take a look more in depth
> >soon.
> >
> >Thanks,
> >Nish
> >
> 
> Hi Nish,
> 
> I only compile-test most of my patch over the weekend.. There are some 
> that I didn't even do compile test on because it's for a different 
> platform (I'm on x86). But yes, I am aware that some of *sleep_on*() 
> family function fixes are not trivial. I only changed ones that I 
> thought trivial. When the end-wait-condition is not clear to me, I left 
> it alone, and I went to the next.

It's not just the wait-condition, it's also the surrounding code
(including how the wait-queue gets woken).

[ On a sidenote: it took me a while to drive this through my own thick
skull, but the *most* important thing to do with KJ patches is
compile-test. If you don't have the arch at hand, get a cross-compiler,
I know there are guides for setting one up around. ]

> Maybe I'm missing something here, but I don't really see why 
> interruptible_sleep_on() or wait_event_interruptible() is not a straight 
> substitution when the caller is not in a loop..

First of all, there's the straightforward semantic difference between
sleeping on a wait queue and waiting for an event! Second, because the
caller is not in a loop, you are introducing a *new* loop by using
wait_event*(). That may not be desired. Depends on the condition you
put in, as well.

> interruptible_sleep_on() does not have a loop inside, and it's a single 
> incantation of wait. When it wakes up, it could be because of a signal 
> or end-condition.

Or someone manually waking up the wait-queue. There is no "end
condition" with sleep_on().

> I see that wait_event_interruptible() has a check outside and a loop 
> inside to ensure that when it returns it's because of a signal or 
> end-condition. (So it's a more correct version of interruptible_sleep_on())

Right, so whereas with sleep_on, waking-up the wait-queue is sufficient
to terminate the sleep, it is *not* for wait_event() -- either the event
*must* be satisfied or a signal *must* have arrived for wait_event() to
return.

> The semantic looks the same to me, so why can't it be a straight 
> substitution when the end-wait-condition is straightforward?
> 
> I don't intend to inject bugs, so I appreciate y'all's review of my 
> patches, and let me know/smack me when I do dumb things.

I appreciate the effort. Getting rid of sleep_on() & co. would be a nice
benefit IMO (or getting it closer to the point where we can mark them
deprecated).

Thanks,
Nish

[-- Attachment #2: Type: text/plain, Size: 168 bytes --]

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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Irwan Djajadi]

Nishanth Aravamudan wrote:
> On 25.10.2005 [21:44:09 -0500], Irwan Djajadi wrote:
> 
>>Nishanth Aravamudan wrote:
>>
>>>On 24.10.2005 [18:46:01 -0500], Irwan Djajadi wrote:
>>>
>>>
>>>>Alexey Dobriyan wrote:
>>>>
>>>>
>>>>
>>>>>On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
>>>>>>wait_event_interruptible()
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>--- 2.6.14-rc5/drivers/block/acsi_slm.c
>>>>>>+++ mod/drivers/block/acsi_slm.c
>>>>>>@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
>>>>>>
>>>>>>	while( SLMState = PRINTING ||
>>>>>>		   (SLMState = FILLING && SLMBufOwner != device) ) {
>>>>>>-		interruptible_sleep_on( &slm_wait );
>>>>>>+		wait_event_interruptible( slm_wait, SLMState=IDLE );
>>>>>>		if (signal_pending(current))
>>>>>>			return( -ERESTARTSYS );
>>>>>>	}
>>>>>>
>>>>>>
>>>>>
>>>>>acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
>>>>
>>>>>from -kj looks more correct.
>>>>
>>>>
>>>>>From: Nishanth Aravamudan
>>>>>
>>>>>Use wait_event_interruptible() instead of the deprecated
>>>>>interruptible_sleep_on(). The sleep_on() call later in the same
>>>>>function is replaced with inline wait-queue code which achieves the
>>>>>same. This required adding a local wait-queue, though.
>>>>>
>>>>>--- a/drivers/block/acsi_slm.c
>>>>>+++ b/drivers/block/acsi_slm.c
>>>>>@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
>>>>>	int		device = iminor(node);
>>>>>	int		n, filled, w, h;
>>>>>
>>>>>-	while( SLMState = PRINTING ||
>>>>>-		   (SLMState = FILLING && SLMBufOwner != device) ) {
>>>>>-		interruptible_sleep_on( &slm_wait );
>>>>>-		if (signal_pending(current))
>>>>>-			return( -ERESTARTSYS );
>>>>>-	}
>>>>>+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
>>>>>+				(SLMState != FILLING || SLMBufOwner = 
>>>>>device)));
>>>>>+	if (signal_pending(current))
>>>>>+		return -ERESTARTSYS;
>>>>>	if (SLMState = IDLE) {
>>>>>		/* first data of page: get current page size  */
>>>>>		if (slm_get_pagesize( device, &w, &h ))
>>>>>
>>>>>
>>>>>
>>>>
>>>>That does look more correct. Please ignore my patch.
>>>>Thanks!
>>>
>>>
>>>@Irwan:
>>>
>>>Have you tested any of the patches you are sending? I stopped replacing
>>>the *sleep_on*() family of functions once I was outside of the domain of
>>>trivial substitution.
>>>
>>>You can't simply s/interruptible_sleep_on/wait_event_interruptible/ as
>>>in many places the sleep_on() caller is not a loop, but one-time sleep!
>>>I have noticed at least one case of this in the patches you are sending
>>>out, but will try to make a more complete analysis soon.
>>>
>>>@Alexey:
>>>
>>>Be very careful pulling in these patches. I don't think any of the
>>>remaining *sleep_on*() replacements are easy or trivial (at least the
>>>ones w/o patches already in -KJ). I'll try to take a look more in depth
>>>soon.
>>>
>>>Thanks,
>>>Nish
>>>
>>
>>Hi Nish,
>>
>>I only compile-test most of my patch over the weekend.. There are some 
>>that I didn't even do compile test on because it's for a different 
>>platform (I'm on x86). But yes, I am aware that some of *sleep_on*() 
>>family function fixes are not trivial. I only changed ones that I 
>>thought trivial. When the end-wait-condition is not clear to me, I left 
>>it alone, and I went to the next.
> 
> 
> It's not just the wait-condition, it's also the surrounding code
> (including how the wait-queue gets woken).
> 
> [ On a sidenote: it took me a while to drive this through my own thick
> skull, but the *most* important thing to do with KJ patches is
> compile-test. If you don't have the arch at hand, get a cross-compiler,
> I know there are guides for setting one up around. ]
> 
> 
>>Maybe I'm missing something here, but I don't really see why 
>>interruptible_sleep_on() or wait_event_interruptible() is not a straight 
>>substitution when the caller is not in a loop..
> 
> 
> First of all, there's the straightforward semantic difference between
> sleeping on a wait queue and waiting for an event! Second, because the
> caller is not in a loop, you are introducing a *new* loop by using
> wait_event*(). That may not be desired. Depends on the condition you
> put in, as well.
> 
> 
>>interruptible_sleep_on() does not have a loop inside, and it's a single 
>>incantation of wait. When it wakes up, it could be because of a signal 
>>or end-condition.
> 
> 
> Or someone manually waking up the wait-queue. There is no "end
> condition" with sleep_on().
> 
> 
>>I see that wait_event_interruptible() has a check outside and a loop 
>>inside to ensure that when it returns it's because of a signal or 
>>end-condition. (So it's a more correct version of interruptible_sleep_on())
> 
> 
> Right, so whereas with sleep_on, waking-up the wait-queue is sufficient
> to terminate the sleep, it is *not* for wait_event() -- either the event
> *must* be satisfied or a signal *must* have arrived for wait_event() to
> return.
> 
> 
>>The semantic looks the same to me, so why can't it be a straight 
>>substitution when the end-wait-condition is straightforward?
>>
>>I don't intend to inject bugs, so I appreciate y'all's review of my 
>>patches, and let me know/smack me when I do dumb things.
> 
> 
> I appreciate the effort. Getting rid of sleep_on() & co. would be a nice
> benefit IMO (or getting it closer to the point where we can mark them
> deprecated).
> 
> Thanks,
> Nish
> 

OK, you're right, the semantic is different..

I've gone back and reviewed my changes, and I think the code before was 
buggy because it should've used the end-condition loop surrounding the 
interruptible_sleep_on, so I think my changes are OK.. IMHO..

Anyway, I think there is a bigger problem even with 
wait_event_interruptible.. When it returns, there is only a guarantee 
that the end-condition happened at the time, but there may not be a 
guarantee that the end-condition is still happening on the current time. 
  I noticed that some drivers uses this synchronization construct to do 
resource management, and I think this is dangerous..

For example: mcdx.c uses it to do locking, swim3.c and swim_iop.c also 
use it for doing "locking" (it waits till fs->state = available, but by 
the time we wake up, fs->state might not be available anymore)..
The rest of the changes mostly have something to do with ASYNC_CLOSING 
stuff with serial port, and using wait_event_interruptible() is probably 
OK here, since hopefully we can only close the serial port once.. or 
something.. :-)

OK, well, lemme know what you think, or maybe I'm just smoking crack
Thanks guys,
--
Irwan
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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Nishanth Aravamudan]

[-- Attachment #1: Type: text/plain, Size: 7486 bytes --]

On 26.10.2005 [23:22:31 -0500], Irwan Djajadi wrote:
> Nishanth Aravamudan wrote:
> >On 25.10.2005 [21:44:09 -0500], Irwan Djajadi wrote:
> >
> >>Nishanth Aravamudan wrote:
> >>
> >>>On 24.10.2005 [18:46:01 -0500], Irwan Djajadi wrote:
> >>>
> >>>
> >>>>Alexey Dobriyan wrote:
> >>>>
> >>>>
> >>>>
> >>>>>On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com 
> >>>>>wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>>drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
> >>>>>>wait_event_interruptible()
> >>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>>--- 2.6.14-rc5/drivers/block/acsi_slm.c
> >>>>>>+++ mod/drivers/block/acsi_slm.c
> >>>>>>@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
> >>>>>>
> >>>>>>	while( SLMState == PRINTING ||
> >>>>>>		   (SLMState == FILLING && SLMBufOwner != device) ) {
> >>>>>>-		interruptible_sleep_on( &slm_wait );
> >>>>>>+		wait_event_interruptible( slm_wait, SLMState==IDLE );
> >>>>>>		if (signal_pending(current))
> >>>>>>			return( -ERESTARTSYS );
> >>>>>>	}
> >>>>>>
> >>>>>>
> >>>>>
> >>>>>acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
> >>>>
> >>>>>from -kj looks more correct.
> >>>>
> >>>>
> >>>>>From: Nishanth Aravamudan
> >>>>>
> >>>>>Use wait_event_interruptible() instead of the deprecated
> >>>>>interruptible_sleep_on(). The sleep_on() call later in the same
> >>>>>function is replaced with inline wait-queue code which achieves the
> >>>>>same. This required adding a local wait-queue, though.
> >>>>>
> >>>>>--- a/drivers/block/acsi_slm.c
> >>>>>+++ b/drivers/block/acsi_slm.c
> >>>>>@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
> >>>>>	int		device = iminor(node);
> >>>>>	int		n, filled, w, h;
> >>>>>
> >>>>>-	while( SLMState == PRINTING ||
> >>>>>-		   (SLMState == FILLING && SLMBufOwner != device) ) {
> >>>>>-		interruptible_sleep_on( &slm_wait );
> >>>>>-		if (signal_pending(current))
> >>>>>-			return( -ERESTARTSYS );
> >>>>>-	}
> >>>>>+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
> >>>>>+				(SLMState != FILLING || SLMBufOwner == 
> >>>>>device)));
> >>>>>+	if (signal_pending(current))
> >>>>>+		return -ERESTARTSYS;
> >>>>>	if (SLMState == IDLE) {
> >>>>>		/* first data of page: get current page size  */
> >>>>>		if (slm_get_pagesize( device, &w, &h ))
> >>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>That does look more correct. Please ignore my patch.
> >>>>Thanks!
> >>>
> >>>
> >>>@Irwan:
> >>>
> >>>Have you tested any of the patches you are sending? I stopped replacing
> >>>the *sleep_on*() family of functions once I was outside of the domain of
> >>>trivial substitution.
> >>>
> >>>You can't simply s/interruptible_sleep_on/wait_event_interruptible/ as
> >>>in many places the sleep_on() caller is not a loop, but one-time sleep!
> >>>I have noticed at least one case of this in the patches you are sending
> >>>out, but will try to make a more complete analysis soon.
> >>>
> >>>@Alexey:
> >>>
> >>>Be very careful pulling in these patches. I don't think any of the
> >>>remaining *sleep_on*() replacements are easy or trivial (at least the
> >>>ones w/o patches already in -KJ). I'll try to take a look more in depth
> >>>soon.
> >>>
> >>>Thanks,
> >>>Nish
> >>>
> >>
> >>Hi Nish,
> >>
> >>I only compile-test most of my patch over the weekend.. There are some 
> >>that I didn't even do compile test on because it's for a different 
> >>platform (I'm on x86). But yes, I am aware that some of *sleep_on*() 
> >>family function fixes are not trivial. I only changed ones that I 
> >>thought trivial. When the end-wait-condition is not clear to me, I left 
> >>it alone, and I went to the next.
> >
> >
> >It's not just the wait-condition, it's also the surrounding code
> >(including how the wait-queue gets woken).
> >
> >[ On a sidenote: it took me a while to drive this through my own thick
> >skull, but the *most* important thing to do with KJ patches is
> >compile-test. If you don't have the arch at hand, get a cross-compiler,
> >I know there are guides for setting one up around. ]
> >
> >
> >>Maybe I'm missing something here, but I don't really see why 
> >>interruptible_sleep_on() or wait_event_interruptible() is not a straight 
> >>substitution when the caller is not in a loop..
> >
> >
> >First of all, there's the straightforward semantic difference between
> >sleeping on a wait queue and waiting for an event! Second, because the
> >caller is not in a loop, you are introducing a *new* loop by using
> >wait_event*(). That may not be desired. Depends on the condition you
> >put in, as well.
> >
> >
> >>interruptible_sleep_on() does not have a loop inside, and it's a single 
> >>incantation of wait. When it wakes up, it could be because of a signal 
> >>or end-condition.
> >
> >
> >Or someone manually waking up the wait-queue. There is no "end
> >condition" with sleep_on().
> >
> >
> >>I see that wait_event_interruptible() has a check outside and a loop 
> >>inside to ensure that when it returns it's because of a signal or 
> >>end-condition. (So it's a more correct version of 
> >>interruptible_sleep_on())
> >
> >
> >Right, so whereas with sleep_on, waking-up the wait-queue is sufficient
> >to terminate the sleep, it is *not* for wait_event() -- either the event
> >*must* be satisfied or a signal *must* have arrived for wait_event() to
> >return.
> >
> >
> >>The semantic looks the same to me, so why can't it be a straight 
> >>substitution when the end-wait-condition is straightforward?
> >>
> >>I don't intend to inject bugs, so I appreciate y'all's review of my 
> >>patches, and let me know/smack me when I do dumb things.
> >
> >
> >I appreciate the effort. Getting rid of sleep_on() & co. would be a nice
> >benefit IMO (or getting it closer to the point where we can mark them
> >deprecated).
> >
> >Thanks,
> >Nish
> >
> 
> OK, you're right, the semantic is different..
> 
> I've gone back and reviewed my changes, and I think the code before was 
> buggy because it should've used the end-condition loop surrounding the 
> interruptible_sleep_on, so I think my changes are OK.. IMHO..
> 
> Anyway, I think there is a bigger problem even with 
> wait_event_interruptible.. When it returns, there is only a guarantee 
> that the end-condition happened at the time, but there may not be a 
> guarantee that the end-condition is still happening on the current time. 
>  I noticed that some drivers uses this synchronization construct to do 
> resource management, and I think this is dangerous..

That would be buggy code, not broken wait_event(). wait_event() waits
for an event and returns when the event is true (or a timeout or a
signal occurs, depending on the actual call). There is never any
gurantee said even is still true.

> For example: mcdx.c uses it to do locking, swim3.c and swim_iop.c also 
> use it for doing "locking" (it waits till fs->state == available, but by 
> the time we wake up, fs->state might not be available anymore)..
> The rest of the changes mostly have something to do with ASYNC_CLOSING 
> stuff with serial port, and using wait_event_interruptible() is probably 
> OK here, since hopefully we can only close the serial port once.. or 
> something.. :-)

It also depends on the codes design. Maybe there is a guarantee, e.g.
that fs->state being made available means that it won't change until our
sleeping task is done. I don't know without looking at the code more
in-depth (which I unfortunately have the time for.

Thanks,
Nish

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Re: [KJ] [PATCH 2.6.14-rc5 1/1] drivers/block/acsi_slm.c: replace

[Irwan Djajadi]

Nishanth Aravamudan wrote:
> On 26.10.2005 [23:22:31 -0500], Irwan Djajadi wrote:
> 
>>Nishanth Aravamudan wrote:
>>
>>>On 25.10.2005 [21:44:09 -0500], Irwan Djajadi wrote:
>>>
>>>
>>>>Nishanth Aravamudan wrote:
>>>>
>>>>
>>>>>On 24.10.2005 [18:46:01 -0500], Irwan Djajadi wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Alexey Dobriyan wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>On Sat, Oct 22, 2005 at 09:53:51PM -0500, irwan.djajadi@iname.com 
>>>>>>>wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>drivers/block/acsi_slm.c: replace interruptible_sleep_on() with
>>>>>>>>wait_event_interruptible()
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>--- 2.6.14-rc5/drivers/block/acsi_slm.c
>>>>>>>>+++ mod/drivers/block/acsi_slm.c
>>>>>>>>@@ -627,7 +627,7 @@ static ssize_t slm_write( struct file *f
>>>>>>>>
>>>>>>>>	while( SLMState = PRINTING ||
>>>>>>>>		   (SLMState = FILLING && SLMBufOwner != device) ) {
>>>>>>>>-		interruptible_sleep_on( &slm_wait );
>>>>>>>>+		wait_event_interruptible( slm_wait, SLMState=IDLE );
>>>>>>>>		if (signal_pending(current))
>>>>>>>>			return( -ERESTARTSYS );
>>>>>>>>	}
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>acsi_slm_replace_interruptible_sleep_on_with_wait_event_interruptible.patch
>>>>>>
>>>>>>>from -kj looks more correct.
>>>>>>
>>>>>>
>>>>>>
>>>>>>>From: Nishanth Aravamudan
>>>>>>>
>>>>>>>Use wait_event_interruptible() instead of the deprecated
>>>>>>>interruptible_sleep_on(). The sleep_on() call later in the same
>>>>>>>function is replaced with inline wait-queue code which achieves the
>>>>>>>same. This required adding a local wait-queue, though.
>>>>>>>
>>>>>>>--- a/drivers/block/acsi_slm.c
>>>>>>>+++ b/drivers/block/acsi_slm.c
>>>>>>>@@ -625,12 +626,10 @@ static ssize_t slm_write( struct file *f
>>>>>>>	int		device = iminor(node);
>>>>>>>	int		n, filled, w, h;
>>>>>>>
>>>>>>>-	while( SLMState = PRINTING ||
>>>>>>>-		   (SLMState = FILLING && SLMBufOwner != device) ) {
>>>>>>>-		interruptible_sleep_on( &slm_wait );
>>>>>>>-		if (signal_pending(current))
>>>>>>>-			return( -ERESTARTSYS );
>>>>>>>-	}
>>>>>>>+	wait_event_interruptible(slm_wait, (SLMState != PRINTING &&
>>>>>>>+				(SLMState != FILLING || SLMBufOwner = 
>>>>>>>device)));
>>>>>>>+	if (signal_pending(current))
>>>>>>>+		return -ERESTARTSYS;
>>>>>>>	if (SLMState = IDLE) {
>>>>>>>		/* first data of page: get current page size  */
>>>>>>>		if (slm_get_pagesize( device, &w, &h ))
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>That does look more correct. Please ignore my patch.
>>>>>>Thanks!
>>>>>
>>>>>
>>>>>@Irwan:
>>>>>
>>>>>Have you tested any of the patches you are sending? I stopped replacing
>>>>>the *sleep_on*() family of functions once I was outside of the domain of
>>>>>trivial substitution.
>>>>>
>>>>>You can't simply s/interruptible_sleep_on/wait_event_interruptible/ as
>>>>>in many places the sleep_on() caller is not a loop, but one-time sleep!
>>>>>I have noticed at least one case of this in the patches you are sending
>>>>>out, but will try to make a more complete analysis soon.
>>>>>
>>>>>@Alexey:
>>>>>
>>>>>Be very careful pulling in these patches. I don't think any of the
>>>>>remaining *sleep_on*() replacements are easy or trivial (at least the
>>>>>ones w/o patches already in -KJ). I'll try to take a look more in depth
>>>>>soon.
>>>>>
>>>>>Thanks,
>>>>>Nish
>>>>>
>>>>
>>>>Hi Nish,
>>>>
>>>>I only compile-test most of my patch over the weekend.. There are some 
>>>>that I didn't even do compile test on because it's for a different 
>>>>platform (I'm on x86). But yes, I am aware that some of *sleep_on*() 
>>>>family function fixes are not trivial. I only changed ones that I 
>>>>thought trivial. When the end-wait-condition is not clear to me, I left 
>>>>it alone, and I went to the next.
>>>
>>>
>>>It's not just the wait-condition, it's also the surrounding code
>>>(including how the wait-queue gets woken).
>>>
>>>[ On a sidenote: it took me a while to drive this through my own thick
>>>skull, but the *most* important thing to do with KJ patches is
>>>compile-test. If you don't have the arch at hand, get a cross-compiler,
>>>I know there are guides for setting one up around. ]
>>>
>>>
>>>
>>>>Maybe I'm missing something here, but I don't really see why 
>>>>interruptible_sleep_on() or wait_event_interruptible() is not a straight 
>>>>substitution when the caller is not in a loop..
>>>
>>>
>>>First of all, there's the straightforward semantic difference between
>>>sleeping on a wait queue and waiting for an event! Second, because the
>>>caller is not in a loop, you are introducing a *new* loop by using
>>>wait_event*(). That may not be desired. Depends on the condition you
>>>put in, as well.
>>>
>>>
>>>
>>>>interruptible_sleep_on() does not have a loop inside, and it's a single 
>>>>incantation of wait. When it wakes up, it could be because of a signal 
>>>>or end-condition.
>>>
>>>
>>>Or someone manually waking up the wait-queue. There is no "end
>>>condition" with sleep_on().
>>>
>>>
>>>
>>>>I see that wait_event_interruptible() has a check outside and a loop 
>>>>inside to ensure that when it returns it's because of a signal or 
>>>>end-condition. (So it's a more correct version of 
>>>>interruptible_sleep_on())
>>>
>>>
>>>Right, so whereas with sleep_on, waking-up the wait-queue is sufficient
>>>to terminate the sleep, it is *not* for wait_event() -- either the event
>>>*must* be satisfied or a signal *must* have arrived for wait_event() to
>>>return.
>>>
>>>
>>>
>>>>The semantic looks the same to me, so why can't it be a straight 
>>>>substitution when the end-wait-condition is straightforward?
>>>>
>>>>I don't intend to inject bugs, so I appreciate y'all's review of my 
>>>>patches, and let me know/smack me when I do dumb things.
>>>
>>>
>>>I appreciate the effort. Getting rid of sleep_on() & co. would be a nice
>>>benefit IMO (or getting it closer to the point where we can mark them
>>>deprecated).
>>>
>>>Thanks,
>>>Nish
>>>
>>
>>OK, you're right, the semantic is different..
>>
>>I've gone back and reviewed my changes, and I think the code before was 
>>buggy because it should've used the end-condition loop surrounding the 
>>interruptible_sleep_on, so I think my changes are OK.. IMHO..
>>
>>Anyway, I think there is a bigger problem even with 
>>wait_event_interruptible.. When it returns, there is only a guarantee 
>>that the end-condition happened at the time, but there may not be a 
>>guarantee that the end-condition is still happening on the current time. 
>> I noticed that some drivers uses this synchronization construct to do 
>>resource management, and I think this is dangerous..
> 
> 
> That would be buggy code, not broken wait_event(). wait_event() waits
> for an event and returns when the event is true (or a timeout or a
> signal occurs, depending on the actual call). There is never any
> gurantee said even is still true.
> 
> 
>>For example: mcdx.c uses it to do locking, swim3.c and swim_iop.c also 
>>use it for doing "locking" (it waits till fs->state = available, but by 
>>the time we wake up, fs->state might not be available anymore)..
>>The rest of the changes mostly have something to do with ASYNC_CLOSING 
>>stuff with serial port, and using wait_event_interruptible() is probably 
>>OK here, since hopefully we can only close the serial port once.. or 
>>something.. :-)
> 
> 
> It also depends on the codes design. Maybe there is a guarantee, e.g.
> that fs->state being made available means that it won't change until our
> sleeping task is done. I don't know without looking at the code more
> in-depth (which I unfortunately have the time for.
> 
> Thanks,
> Nish
> 

Yes, I agree.. That was what I was trying to say, that those drivers 
maybe using the wrong synchronization construct.. and not really 
wait_event*() problem.

:-) Yeah, I chose to just replace sleep_on() functions with the blessed 
ones, and not trying to fix the buggy drivers. At least with my patch, 
they're "better" in terms of using the non-deprecated funcs, but 
bugginess-wise, they'll be about the same... oh well..

Thanks man
--
Irwan
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