Hi,
a (very) simple grep in drivers/ showed more than 300 matches of code like
this:
foo = kmalloc(bar, baz);
if (! foo)
return -ENOMEM;
memset(foo, 0, sizeof(foo));
Why not add a small inlined function doing the memset for us
and reducing the code to
foo = kmalloc0(bar, baz);
if (! foo)
return -ENOMEM;
Eike
--- linux-2.6.0-test5-bk1/include/linux/slab.h 2003-09-11 15:19:40.000000000 +0200
+++ linux-2.6.0-test5-bk1-caliban/include/linux/slab.h 2003-09-11 15:22:56.000000000 +0200
@@ -14,6 +14,7 @@
#include <linux/config.h> /* kmalloc_sizes.h needs CONFIG_ options */
#include <linux/gfp.h>
#include <linux/types.h>
+#include <linux/string.h> /* for memset */
#include <asm/page.h> /* kmalloc_sizes.h needs PAGE_SIZE */
#include <asm/cache.h> /* kmalloc_sizes.h needs L1_CACHE_BYTES */
@@ -97,6 +98,16 @@
return __kmalloc(size, flags);
}
+static inline void *kmalloc0(size_t size, int flags)
+{
+ void *res = kmalloc(size, flags);
+
+ if (res != NULL)
+ memset(res, 0, size);
+
+ return res;
+}
+
extern void kfree(const void *);
extern unsigned int ksize(const void *);
On Thu, Sep 11, 2003 at 03:40:58PM +0200, Rolf Eike Beer wrote:
> Hi,
>
> a (very) simple grep in drivers/ showed more than 300 matches of code like
> this:
>
> foo = kmalloc(bar, baz);
> if (! foo)
> return -ENOMEM;
> memset(foo, 0, sizeof(foo));
Erm. It would better *not* be there in such amounts - sizeof(foo) would
be a size of pointer...
> Why not add a small inlined function doing the memset for us
> and reducing the code to
>
> foo = kmalloc0(bar, baz);
> if (! foo)
> return -ENOMEM;
Bad choice of name - too easy to confuse with kmalloc().
Do correct kmalloc+memset in new funcion.
Breno
----- Original Message -----
From: "Rolf Eike Beer" <[email protected]>
To: <[email protected]>
Sent: Thursday, September 11, 2003 10:40 AM
Subject: [RFC][PATCH] kmalloc + memset(foo, 0, bar) = kmalloc0
> Hi,
>
> a (very) simple grep in drivers/ showed more than 300 matches of code like
> this:
>
> foo = kmalloc(bar, baz);
> if (! foo)
> return -ENOMEM;
> memset(foo, 0, sizeof(foo));
>
> Why not add a small inlined function doing the memset for us
> and reducing the code to
>
> foo = kmalloc0(bar, baz);
> if (! foo)
> return -ENOMEM;
>
> Eike
>
> --- linux-2.6.0-test5-bk1/include/linux/slab.h 2003-09-11
15:19:40.000000000 +0200
> +++ linux-2.6.0-test5-bk1-caliban/include/linux/slab.h 2003-09-11
15:22:56.000000000 +0200
> @@ -14,6 +14,7 @@
> #include <linux/config.h> /* kmalloc_sizes.h needs CONFIG_ options */
> #include <linux/gfp.h>
> #include <linux/types.h>
> +#include <linux/string.h> /* for memset */
> #include <asm/page.h> /* kmalloc_sizes.h needs PAGE_SIZE */
> #include <asm/cache.h> /* kmalloc_sizes.h needs L1_CACHE_BYTES */
>
> @@ -97,6 +98,16 @@
> return __kmalloc(size, flags);
> }
>
> +static inline void *kmalloc0(size_t size, int flags)
> +{
> + void *res = kmalloc(size, flags);
> +
> + if (res != NULL)
> + memset(res, 0, size);
> +
> + return res;
> +}
> +
> extern void kfree(const void *);
> extern unsigned int ksize(const void *);
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
Am Donnerstag, 11. September 2003 15:45 schrieben Sie:
> On Thu, Sep 11, 2003 at 03:40:58PM +0200, Rolf Eike Beer wrote:
> > Hi,
> >
> > a (very) simple grep in drivers/ showed more than 300 matches of code
> > like this:
> >
> > foo = kmalloc(bar, baz);
> > if (! foo)
> > return -ENOMEM;
> > memset(foo, 0, sizeof(foo));
> Erm. It would better *not* be there in such amounts - sizeof(foo) would
> be a size of pointer...
Eek, yes. Typo from me.
> > Why not add a small inlined function doing the memset for us
> > and reducing the code to
> >
> > foo = kmalloc0(bar, baz);
> > if (! foo)
> > return -ENOMEM;
>
> Bad choice of name - too easy to confuse with kmalloc().
Yes, maybe. But don't expect more innovations from me today, it's someone
else's turn ;)
Eike
[email protected] wrote:
> Bad choice of name - too easy to confuse with kmalloc().
kmalloc_and_zero() would be much clearer.
It opens the way for a pool of pre-zeroed pages, too. We know that
improves preformance on some architectures.
-- Jamie
On 09.11, Jamie Lokier wrote:
> [email protected] wrote:
> > Bad choice of name - too easy to confuse with kmalloc().
>
> kmalloc_and_zero() would be much clearer.
>
Why not kcalloc() ?
--
J.A. Magallon <[email protected]> \ Software is like sex:
werewolf.able.es \ It's better when it's free
Mandrake Linux release 9.2 (Cooker) for i586
Linux 2.4.23-pre2-jam1m (gcc 3.3.1 (Mandrake Linux 9.2 3.3.1-1mdk))
On Iau, 2003-09-11 at 22:58, J.A. Magallon wrote:
> On 09.11, Jamie Lokier wrote:
> > [email protected] wrote:
> > > Bad choice of name - too easy to confuse with kmalloc().
> >
> > kmalloc_and_zero() would be much clearer.
> >
>
> Why not kcalloc() ?
A kcalloc that also checked for maths overflows would probably
help avoid various errors and checks against ~0/sizeof(n) in
drivers we have now
On 09.12, Alan Cox wrote:
> On Iau, 2003-09-11 at 22:58, J.A. Magallon wrote:
> > On 09.11, Jamie Lokier wrote:
> > > [email protected] wrote:
> > > > Bad choice of name - too easy to confuse with kmalloc().
> > >
> > > kmalloc_and_zero() would be much clearer.
> > >
> >
> > Why not kcalloc() ?
>
> A kcalloc that also checked for maths overflows would probably
> help avoid various errors and checks against ~0/sizeof(n) in
> drivers we have now
>
Some time ago when I tried to do some wrappers, I choosed something
like this (k-prefixed here for kernel...):
void* kalloc(size_t size)
void* kvalloc(size_t size,size_t num)
void* kallocz(size_t size) // or kalloc_z, clearer...
void* kvallocz(size_t size,size_t num) // kvalloc_z
void* kfree(void*)
And if you don't hate too much C++
#define knew(mytype) (mytype*)kalloc(sizeof(mytype))
#define kvnew(mytype,n) (mytype*)kvalloc(sizeof(mytype),n)
and so on...
I can tell for sure they clarify the code very much... and you
don't forget the NULL check anymore ;).
--
J.A. Magallon <[email protected]> \ Software is like sex:
werewolf.able.es \ It's better when it's free
Mandrake Linux release 9.2 (Cooker) for i586
Linux 2.4.23-pre2-jam1m (gcc 3.3.1 (Mandrake Linux 9.2 3.3.1-1mdk))