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Date: Thu, 26 Apr 2012 10:58:55 +0900 From: Minchan Kim <minchan@...nel.org> To: Nitin Gupta <ngupta@...are.org> CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Seth Jennings <sjenning@...ux.vnet.ibm.com>, Dan Magenheimer <dan.magenheimer@...cle.com>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: Re: [PATCH 5/6] zsmalloc: remove unnecessary type casting On 04/25/2012 10:35 PM, Nitin Gupta wrote: > On 04/25/2012 02:23 AM, Minchan Kim wrote: > >> Let's remove unnecessary type casting of (void *). >> >> Signed-off-by: Minchan Kim <minchan@...nel.org> >> --- >> drivers/staging/zsmalloc/zsmalloc-main.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c >> index b7d31cc..ff089f8 100644 >> --- a/drivers/staging/zsmalloc/zsmalloc-main.c >> +++ b/drivers/staging/zsmalloc/zsmalloc-main.c >> @@ -644,8 +644,7 @@ void zs_free(struct zs_pool *pool, void *obj) >> spin_lock(&class->lock); >> >> /* Insert this object in containing zspage's freelist */ >> - link = (struct link_free *)((unsigned char *)kmap_atomic(f_page) >> - + f_offset); >> + link = (struct link_free *)(kmap_atomic(f_page) + f_offset); >> link->next = first_page->freelist; >> kunmap_atomic(link); >> first_page->freelist = obj; > > > > Incrementing a void pointer looks weired and should not be allowed by C > compilers though gcc and clang seem to allow this without any warnings. > (fortunately C++ forbids incrementing void pointers) It's a gcc extension and we have been already used lots of place so I think it's no problem although it's non-standard. If we compile kernel with -Wpointer-arith, we would find a ton of warning in here and there. > > So, we should keep this cast to unsigned char pointer to avoid relying > on a non-standard, compiler specific behavior. Okay. It's a just trivial and I have no justification to do it at the cost of breaking standard. > > Thanks, > Nitin > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@...ck.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a> > -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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