Re: CVS commit: src/sys/sys

[Marc Balmer]

Am 17.07.2014 um 16:55 schrieb Taylor R Campbell riastr...@netbsd.org:

 Module Name:  src
 Committed By: riastradh
 Date: Thu Jul 17 14:55:32 UTC 2014
 
 Modified Files:
   src/sys/sys: systm.h
 
 Log Message:
 Expand null macros to `do {} while (0)', not to nothing.
 
 

Not that I object, but out of curiosity, what is this good for, or, why is this 
need/a good thing?

 Index: src/sys/sys/systm.h
 diff -u src/sys/sys/systm.h:1.263 src/sys/sys/systm.h:1.264
 --- src/sys/sys/systm.h:1.263 Thu Apr  3 15:22:57 2014
 +++ src/sys/sys/systm.h   Thu Jul 17 14:55:32 2014
 @@ -1,4 +1,4 @@
 -/*   $NetBSD: systm.h,v 1.263 2014/04/03 15:22:57 christos Exp $ */
 +/*   $NetBSD: systm.h,v 1.264 2014/07/17 14:55:32 riastradh Exp $*/
 
 /*-
  * Copyright (c) 1982, 1988, 1991, 1993
 @@ -527,7 +527,7 @@ void assert_sleepable(void);
 #if defined(DEBUG)
 #define   ASSERT_SLEEPABLE()  assert_sleepable()
 #else /* defined(DEBUG) */
 -#define  ASSERT_SLEEPABLE()  /* nothing */
 +#define  ASSERT_SLEEPABLE()  do {} while (0)
 #endif /* defined(DEBUG) */
 
 vaddr_t calc_cache_size(vsize_t , int, int);
 

Re: CVS commit: src/sys/sys

[Lourival Vieira Neto]

On Thu, Jul 17, 2014 at 3:14 PM, Marc Balmer m...@msys.ch wrote:

 Am 17.07.2014 um 16:55 schrieb Taylor R Campbell riastr...@netbsd.org:

 Module Name:  src
 Committed By: riastradh
 Date: Thu Jul 17 14:55:32 UTC 2014

 Modified Files:
   src/sys/sys: systm.h

 Log Message:
 Expand null macros to `do {} while (0)', not to nothing.



 Not that I object, but out of curiosity, what is this good for, or, why is 
 this need/a good thing?

 Index: src/sys/sys/systm.h
 diff -u src/sys/sys/systm.h:1.263 src/sys/sys/systm.h:1.264
 --- src/sys/sys/systm.h:1.263 Thu Apr  3 15:22:57 2014
 +++ src/sys/sys/systm.h   Thu Jul 17 14:55:32 2014
 @@ -1,4 +1,4 @@
 -/*   $NetBSD: systm.h,v 1.263 2014/04/03 15:22:57 christos Exp $ */
 +/*   $NetBSD: systm.h,v 1.264 2014/07/17 14:55:32 riastradh Exp $*/

 /*-
  * Copyright (c) 1982, 1988, 1991, 1993
 @@ -527,7 +527,7 @@ void assert_sleepable(void);
 #if defined(DEBUG)
 #define   ASSERT_SLEEPABLE()  assert_sleepable()
 #else /* defined(DEBUG) */
 -#define  ASSERT_SLEEPABLE()  /* nothing */
 +#define  ASSERT_SLEEPABLE()  do {} while (0)
 #endif /* defined(DEBUG) */

 vaddr_t calc_cache_size(vsize_t , int, int);


Wouldn't be '((void)0)' better?
Regards,
-- 
Lourival Vieira Neto

re: CVS commit: src/sys/dev/usb

[matthew green]

Taylor R Campbell writes:
 Module Name:  src
 Committed By: riastradh
 Date: Thu Jul 17 18:42:38 UTC 2014
 
 Modified Files:
   src/sys/dev/usb: usb.c usbdi.h
 
 Log Message:
 Fix usb task queue locking.

why does this take the lock and then use atomic operations?

such strange usage should have a comment..

thanks.


.mrg.

Re: CVS commit: src/sys/dev/usb

[Taylor R Campbell]

   Date: Fri, 18 Jul 2014 11:58:33 +1000
   from: matthew green m...@eterna.com.au

   Taylor R Campbell writes:
Fix usb task queue locking.

   why does this take the lock and then use atomic operations?

Reading task-queue is not covered by a lock: until you know what it
is you don't know what lock to hold.  usb_task_rem needs to read it
and use it without holding any queue's lock, and by the time
usb_task_rem takes a lock, the value it read may be out of date.

   such strange usage should have a comment..

Better yet, we should have a better task queue system.  More on that
soon, perhaps...