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Date: Tue, 18 Oct 2016 14:34:41 -0400
From: "Emilio G. Cota" <cota@braap.org>
Message-ID: <20161018183441.GB9586@flamenco>
References: <20161018145620.20658-1-bobby.prani@gmail.com>
	<20161018145620.20658-2-bobby.prani@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 2/2] translate-all: Use proper type
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To: Pranith Kumar <bobby.prani@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Richard Henderson <rth@twiddle.net>, "open list:Overall" <qemu-devel@nongnu.org>

On Tue, Oct 18, 2016 at 10:56:20 -0400, Pranith Kumar wrote:
> gcc does not warn about the wrong type since it is a void pointer
> which can be cast to any type.
> 
> Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
> ---
>  translate-all.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/translate-all.c b/translate-all.c
> index 8ca393c..c77470a 100644
> --- a/translate-all.c
> +++ b/translate-all.c
> @@ -412,7 +412,7 @@ static PageDesc *page_find_alloc(tb_page_addr_t index, int alloc)
>  
>      /* Level 2..N-1.  */
>      for (i = V_L1_SHIFT / V_L2_BITS - 1; i > 0; i--) {
> -        void **p = atomic_rcu_read(lp);
> +        void *p = atomic_rcu_read(lp);
>  
>          if (p == NULL) {
>              if (!alloc) {

Let me redo your patch with more context (for patches like this using
format-patch -U<n> is useful):

$ git diff -U11 translate-all.c
diff --git a/translate-all.c b/translate-all.c
index 4200869..6928ace 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -405,23 +405,23 @@ static void page_init(void)
 static PageDesc *page_find_alloc(tb_page_addr_t index, int alloc)
 {
     PageDesc *pd;
     void **lp;
     int i;

     /* Level 1.  Always allocated.  */
     lp = l1_map + ((index >> V_L1_SHIFT) & (V_L1_SIZE - 1));

     /* Level 2..N-1.  */
     for (i = V_L1_SHIFT / V_L2_BITS - 1; i > 0; i--) {
-        void **p = atomic_rcu_read(lp);
+        void *p = atomic_rcu_read(lp);

         if (p == NULL) {
             if (!alloc) {
                 return NULL;
             }
             p = g_new0(void *, V_L2_SIZE);
             atomic_rcu_set(lp, p);
         }

         lp = p + ((index >> (i * V_L2_BITS)) & (V_L2_SIZE - 1));
     }

I prefer void **p since that matches lp's and l1_map's type.

It's true that since we're dealing with void * the compiler won't
complain either way.

		Emilio