Re: [patch 2/9] Store max number of objects in the page struct.

Re: [patch 2/9] Store max number of objects in the page struct.

[Zhang, Yanmin]

On Wed, 2008-03-19 at 10:49 -0700, Christoph Lameter wrote:
> On Wed, 19 Mar 2008, Zhang, Yanmin wrote:
> 
> > > +	if ((PAGE_SIZE << min_order) / size > 65535)
> > > +		return get_order(size * 65535) - 1;
> > Is it better to define something like USHORT_MAX to replace 65535?
> 
> Yes. Do we have something like that?

I couldn't find such definition in include/linux/kernel.h.


But glibc defines USHRT_MAX file include/limits.h:

/* Minimum and maximum values a `signed short int' can hold.  */
#  define SHRT_MIN      (-32768)
#  define SHRT_MAX      32767

/* Maximum value an `unsigned short int' can hold.  (Minimum is 0.)  */
#  define USHRT_MAX     65535


How about below patch against 2.6.25-rc6?

---

Add definitions of USHRT_MAX and others into kernel. ipc uses it and
slub implementation might also use it.

The patch is against 2.6.25-rc6.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>

---

--- linux-2.6.25-rc6/include/linux/kernel.h	2008-03-20 04:25:46.000000000 +0800
+++ linux-2.6.25-rc6_work/include/linux/kernel.h	2008-03-20 04:17:45.000000000 +0800
@@ -20,6 +20,9 @@
 extern const char linux_banner[];
 extern const char linux_proc_banner[];
 
+#define USHRT_MAX	((u16)(~0U))
+#define SHRT_MAX	((s16)(USHRT_MAX>>1))
+#define SHRT_MIN	(-SHRT_MAX - 1)
 #define INT_MAX		((int)(~0U>>1))
 #define INT_MIN		(-INT_MAX - 1)
 #define UINT_MAX	(~0U)
--- linux-2.6.25-rc6/ipc/util.h	2008-03-20 04:25:46.000000000 +0800
+++ linux-2.6.25-rc6_work/ipc/util.h	2008-03-20 04:22:07.000000000 +0800
@@ -12,7 +12,6 @@
 
 #include <linux/err.h>
 
-#define USHRT_MAX 0xffff
 #define SEQ_MULTIPLIER	(IPCMNI)
 
 void sem_init (void);

Re: [patch 2/9] Store max number of objects in the page struct.

[Christoph Lameter]

Reviewed-by: Christoph Lameter <clameter@sgi.com>

On Thu, 20 Mar 2008, Zhang, Yanmin wrote:

> On Wed, 2008-03-19 at 10:49 -0700, Christoph Lameter wrote:
> > On Wed, 19 Mar 2008, Zhang, Yanmin wrote:
> > 
> > > > +	if ((PAGE_SIZE << min_order) / size > 65535)
> > > > +		return get_order(size * 65535) - 1;
> > > Is it better to define something like USHORT_MAX to replace 65535?
> > 
> > Yes. Do we have something like that?
> 
> I couldn't find such definition in include/linux/kernel.h.
> 
> 
> But glibc defines USHRT_MAX file include/limits.h:
> 
> /* Minimum and maximum values a `signed short int' can hold.  */
> #  define SHRT_MIN      (-32768)
> #  define SHRT_MAX      32767
> 
> /* Maximum value an `unsigned short int' can hold.  (Minimum is 0.)  */
> #  define USHRT_MAX     65535
> 
> 
> How about below patch against 2.6.25-rc6?
> 
> ---
> 
> Add definitions of USHRT_MAX and others into kernel. ipc uses it and
> slub implementation might also use it.
> 
> The patch is against 2.6.25-rc6.
> 
> Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
> 
> ---
> 
> --- linux-2.6.25-rc6/include/linux/kernel.h	2008-03-20 04:25:46.000000000 +0800
> +++ linux-2.6.25-rc6_work/include/linux/kernel.h	2008-03-20 04:17:45.000000000 +0800
> @@ -20,6 +20,9 @@
>  extern const char linux_banner[];
>  extern const char linux_proc_banner[];
>  
> +#define USHRT_MAX	((u16)(~0U))
> +#define SHRT_MAX	((s16)(USHRT_MAX>>1))
> +#define SHRT_MIN	(-SHRT_MAX - 1)
>  #define INT_MAX		((int)(~0U>>1))
>  #define INT_MIN		(-INT_MAX - 1)
>  #define UINT_MAX	(~0U)
> --- linux-2.6.25-rc6/ipc/util.h	2008-03-20 04:25:46.000000000 +0800
> +++ linux-2.6.25-rc6_work/ipc/util.h	2008-03-20 04:22:07.000000000 +0800
> @@ -12,7 +12,6 @@
>  
>  #include <linux/err.h>
>  
> -#define USHRT_MAX 0xffff
>  #define SEQ_MULTIPLIER	(IPCMNI)
>  
>  void sem_init (void);
> 
> 
> 
> 
> 
> 
> 

Re: [patch 2/9] Store max number of objects in the page struct.

[Andrew Morton]

On Thu, 20 Mar 2008 11:32:17 +0800
"Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:

> Add definitions of USHRT_MAX and others into kernel. ipc uses it and
> slub implementation might also use it.
> 
> The patch is against 2.6.25-rc6.
> 
> Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
> 
> ---
> 
> --- linux-2.6.25-rc6/include/linux/kernel.h	2008-03-20 04:25:46.000000000 +0800
> +++ linux-2.6.25-rc6_work/include/linux/kernel.h	2008-03-20 04:17:45.000000000 +0800
> @@ -20,6 +20,9 @@
>  extern const char linux_banner[];
>  extern const char linux_proc_banner[];
>  
> +#define USHRT_MAX	((u16)(~0U))
> +#define SHRT_MAX	((s16)(USHRT_MAX>>1))
> +#define SHRT_MIN	(-SHRT_MAX - 1)

We have UINT_MAX and ULONG_MAX and ULLONG_MAX.  If these were actually
UNT_MAX, ULNG_MAX and ULLNG_MAX then USHRT_MAX would make sense.

But they aren't, so it doesn't ;)

Please, let's call them USHORT_MAX, SHORT_MAX and SHORT_MIN.

> --- linux-2.6.25-rc6/ipc/util.h	2008-03-20 04:25:46.000000000 +0800
> +++ linux-2.6.25-rc6_work/ipc/util.h	2008-03-20 04:22:07.000000000 +0800
> @@ -12,7 +12,6 @@
>  
>  #include <linux/err.h>
>  
> -#define USHRT_MAX 0xffff
>  #define SEQ_MULTIPLIER	(IPCMNI)
>  
>  void sem_init (void);

And then convert IPC to use them?

Re: [patch 2/9] Store max number of objects in the page struct.

[Ben Pfaff]

Andrew Morton <akpm@linux-foundation.org> writes:

>> +#define USHRT_MAX	((u16)(~0U))
>> +#define SHRT_MAX	((s16)(USHRT_MAX>>1))
>> +#define SHRT_MIN	(-SHRT_MAX - 1)
>
> We have UINT_MAX and ULONG_MAX and ULLONG_MAX.  If these were actually
> UNT_MAX, ULNG_MAX and ULLNG_MAX then USHRT_MAX would make sense.
>
> But they aren't, so it doesn't ;)
>
> Please, let's call them USHORT_MAX, SHORT_MAX and SHORT_MIN.

SHRT_MIN, SHRT_MAX, and USHRT_MAX are the spellings used by
<limits.h> required in ISO-conforming C implementations.  That
doesn't mean that the kernel has to use those spellings, but it
does mean that those names are widely understood by C
programmers.
-- 
Ben Pfaff 
http://benpfaff.org

[PATCH] Add definitions of USHORT_MAX and others

[Zhang, Yanmin]

Below is the new patch. Thanks for the comments.

---

Add definitions of USHORT_MAX and others into kernel. ipc uses it and
slub implementation might also use it.

The patch is against 2.6.25-rc6.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
Reviewed-by: Christoph Lameter <clameter@sgi.com>

---

diff -Nraup linux-2.6.25-rc6/include/linux/kernel.h linux-2.6.25-rc6_maxshort/include/linux/kernel.h
--- linux-2.6.25-rc6/include/linux/kernel.h	2008-03-24 02:05:25.000000000 +0800
+++ linux-2.6.25-rc6_maxshort/include/linux/kernel.h	2008-03-24 02:07:27.000000000 +0800
@@ -20,6 +20,9 @@
 extern const char linux_banner[];
 extern const char linux_proc_banner[];
 
+#define USHORT_MAX	((u16)(~0U))
+#define SHORT_MAX	((s16)(USHORT_MAX>>1))
+#define SHORT_MIN	(-SHORT_MAX - 1)
 #define INT_MAX		((int)(~0U>>1))
 #define INT_MIN		(-INT_MAX - 1)
 #define UINT_MAX	(~0U)
diff -Nraup linux-2.6.25-rc6/ipc/msg.c linux-2.6.25-rc6_maxshort/ipc/msg.c
--- linux-2.6.25-rc6/ipc/msg.c	2008-03-24 02:05:25.000000000 +0800
+++ linux-2.6.25-rc6_maxshort/ipc/msg.c	2008-03-24 02:07:27.000000000 +0800
@@ -324,19 +324,19 @@ copy_msqid_to_user(void __user *buf, str
 		out.msg_rtime		= in->msg_rtime;
 		out.msg_ctime		= in->msg_ctime;
 
-		if (in->msg_cbytes > USHRT_MAX)
-			out.msg_cbytes	= USHRT_MAX;
+		if (in->msg_cbytes > USHORT_MAX)
+			out.msg_cbytes	= USHORT_MAX;
 		else
 			out.msg_cbytes	= in->msg_cbytes;
 		out.msg_lcbytes		= in->msg_cbytes;
 
-		if (in->msg_qnum > USHRT_MAX)
-			out.msg_qnum	= USHRT_MAX;
+		if (in->msg_qnum > USHORT_MAX)
+			out.msg_qnum	= USHORT_MAX;
 		else
 			out.msg_qnum	= in->msg_qnum;
 
-		if (in->msg_qbytes > USHRT_MAX)
-			out.msg_qbytes	= USHRT_MAX;
+		if (in->msg_qbytes > USHORT_MAX)
+			out.msg_qbytes	= USHORT_MAX;
 		else
 			out.msg_qbytes	= in->msg_qbytes;
 		out.msg_lqbytes		= in->msg_qbytes;
diff -Nraup linux-2.6.25-rc6/ipc/util.c linux-2.6.25-rc6_maxshort/ipc/util.c
--- linux-2.6.25-rc6/ipc/util.c	2008-03-24 02:05:25.000000000 +0800
+++ linux-2.6.25-rc6_maxshort/ipc/util.c	2008-03-24 02:07:27.000000000 +0800
@@ -84,8 +84,8 @@ void ipc_init_ids(struct ipc_ids *ids)
 	ids->seq = 0;
 	{
 		int seq_limit = INT_MAX/SEQ_MULTIPLIER;
-		if(seq_limit > USHRT_MAX)
-			ids->seq_max = USHRT_MAX;
+		if(seq_limit > USHORT_MAX)
+			ids->seq_max = USHORT_MAX;
 		 else
 		 	ids->seq_max = seq_limit;
 	}
diff -Nraup linux-2.6.25-rc6/ipc/util.h linux-2.6.25-rc6_maxshort/ipc/util.h
--- linux-2.6.25-rc6/ipc/util.h	2008-03-24 02:05:25.000000000 +0800
+++ linux-2.6.25-rc6_maxshort/ipc/util.h	2008-03-24 02:07:27.000000000 +0800
@@ -12,7 +12,6 @@
 
 #include <linux/err.h>
 
-#define USHRT_MAX 0xffff
 #define SEQ_MULTIPLIER	(IPCMNI)
 
 void sem_init (void);