[patch] IPV4 spinlock_casting

[patch] IPV4 spinlock_casting

[Sven-Thorsten Dietrich]

Fix a compile error in net/ipv4/route.c when RT patch is applied:

LD      .tmp_vmlinux1
net/built-in.o(.text+0x19058): In function `rt_check_expire':
net/ipv4/route.c:628: undefined reference to `__bad_spinlock_type'
net/built-in.o(.text+0x1907a):net/ipv4/route.c:661: undefined reference to `__bad_spinlock_type'
net/built-in.o(.text+0x1918b): In function `rt_run_flush':
net/ipv4/route.c:684: undefined reference to `__bad_spinlock_type'
net/built-in.o(.text+0x191a3):net/ipv4/route.c:688: undefined reference to `__bad_spinlock_type'
net/built-in.o(.text+0x193b9): In function `rt_garbage_collect':
net/ipv4/route.c:821: undefined reference to `__bad_spinlock_type'
net/built-in.o(.text+0x193e7):net/ipv4/route.c:853: more undefined references to `__bad_spinlock_type' follow
make: *** [.tmp_vmlinux1] Error 1

Problem is related to the RT PICK_OP function.

Adds explicit casting to spinlock_t (whatever that happens to be for the
given .config)

Signed-off-by: Sven-Thorsten Dietrich <sdietrich@mvista.com>

Index: linux-2.6.13-rc4-RT-V0.7.52-14/net/ipv4/route.c
===================================================================
--- linux-2.6.13-rc4-RT-V0.7.52-14.orig/net/ipv4/route.c
+++ linux-2.6.13-rc4-RT-V0.7.52-14/net/ipv4/route.c
@@ -228,7 +228,7 @@
 		rt_hash_locks = kmalloc(sizeof(spinlock_t) * RT_HASH_LOCK_SZ, GFP_KERNEL); \
 		if (!rt_hash_locks) panic("IP: failed to allocate rt_hash_locks\n"); \
 		for (i = 0; i < RT_HASH_LOCK_SZ; i++) \
-			spin_lock_init(&rt_hash_locks[i]); \
+			spin_lock_init((spinlock_t *) &rt_hash_locks[i]); \
 		}
 #else
 # define rt_hash_lock_addr(slot) NULL
@@ -625,7 +625,7 @@
 
 		if (*rthp == 0)
 			continue;
-		spin_lock(rt_hash_lock_addr(i));
+		spin_lock((spinlock_t *) rt_hash_lock_addr(i));
 		while ((rth = *rthp) != NULL) {
 			if (rth->u.dst.expires) {
 				/* Entry is expired even if it is in use */
@@ -658,7 +658,7 @@
  			rt_free(rth);
 #endif /* CONFIG_IP_ROUTE_MULTIPATH_CACHED */
 		}
-		spin_unlock(rt_hash_lock_addr(i));
+		spin_unlock((spinlock_t *) rt_hash_lock_addr(i));
 
 		/* Fallback loop breaker. */
 		if (time_after(jiffies, now))
@@ -681,11 +681,11 @@
 	get_random_bytes(&rt_hash_rnd, 4);
 
 	for (i = rt_hash_mask; i >= 0; i--) {
-		spin_lock_bh(rt_hash_lock_addr(i));
+		spin_lock_bh((spinlock_t *) rt_hash_lock_addr(i));
 		rth = rt_hash_table[i].chain;
 		if (rth)
 			rt_hash_table[i].chain = NULL;
-		spin_unlock_bh(rt_hash_lock_addr(i));
+		spin_unlock_bh((spinlock_t *) rt_hash_lock_addr(i));
 
 		for (; rth; rth = next) {
 			next = rth->u.rt_next;
@@ -818,7 +818,7 @@
 
 			k = (k + 1) & rt_hash_mask;
 			rthp = &rt_hash_table[k].chain;
-			spin_lock_bh(rt_hash_lock_addr(k));
+			spin_lock_bh((spinlock_t *) rt_hash_lock_addr(k));
 			while ((rth = *rthp) != NULL) {
 				if (!rt_may_expire(rth, tmo, expire)) {
 					tmo >>= 1;
@@ -850,7 +850,7 @@
 				goal--;
 #endif /* CONFIG_IP_ROUTE_MULTIPATH_CACHED */
 			}
-			spin_unlock_bh(rt_hash_lock_addr(k));
+			spin_unlock_bh((spinlock_t *)rt_hash_lock_addr(k));
 			if (goal <= 0)
 				break;
 		}
@@ -920,7 +920,7 @@
 
 	rthp = &rt_hash_table[hash].chain;
 
-	spin_lock_bh(rt_hash_lock_addr(hash));
+	spin_lock_bh((spinlock_t *) rt_hash_lock_addr(hash));
 	while ((rth = *rthp) != NULL) {
 #ifdef CONFIG_IP_ROUTE_MULTIPATH_CACHED
 		if (!(rth->u.dst.flags & DST_BALANCED) &&
@@ -946,7 +946,7 @@
 			rth->u.dst.__use++;
 			dst_hold(&rth->u.dst);
 			rth->u.dst.lastuse = now;
-			spin_unlock_bh(rt_hash_lock_addr(hash));
+			spin_unlock_bh((spinlock_t *)rt_hash_lock_addr(hash));
 
 			rt_drop(rt);
 			*rp = rth;
@@ -987,7 +987,7 @@
 	if (rt->rt_type == RTN_UNICAST || rt->fl.iif == 0) {
 		int err = arp_bind_neighbour(&rt->u.dst);
 		if (err) {
-			spin_unlock_bh(rt_hash_lock_addr(hash));
+			spin_unlock_bh((spinlock_t *)rt_hash_lock_addr(hash));
 
 			if (err != -ENOBUFS) {
 				rt_drop(rt);
@@ -1028,7 +1028,7 @@
 	}
 #endif
 	rt_hash_table[hash].chain = rt;
-	spin_unlock_bh(rt_hash_lock_addr(hash));
+	spin_unlock_bh((spinlock_t *)rt_hash_lock_addr(hash));
 	*rp = rt;
 	return 0;
 }
@@ -1096,7 +1096,7 @@
 {
 	struct rtable **rthp;
 
-	spin_lock_bh(rt_hash_lock_addr(hash));
+	spin_lock_bh((spinlock_t *) rt_hash_lock_addr(hash));
 	ip_rt_put(rt);
 	for (rthp = &rt_hash_table[hash].chain; *rthp;
 	     rthp = &(*rthp)->u.rt_next)
@@ -1105,7 +1105,7 @@
 			rt_free(rt);
 			break;
 		}
-	spin_unlock_bh(rt_hash_lock_addr(hash));
+	spin_unlock_bh((spinlock_t *) rt_hash_lock_addr(hash));
 }
 
 void ip_rt_redirect(u32 old_gw, u32 daddr, u32 new_gw,

Re: [patch] IPV4 spinlock_casting

[Ingo Molnar]

* Sven-Thorsten Dietrich <sdietrich@mvista.com> wrote:

> Fix a compile error in net/ipv4/route.c when RT patch is applied:

> Index: linux-2.6.13-rc4-RT-V0.7.52-14/net/ipv4/route.c

are you sure you are seeing this with the -52-14 patch? If yes then 
please send me your .config.

the build error showed a more fundamental bug, which had to be solved 
differently. The problem was the code in route.c, the problem was this:

 # define rt_hash_lock_addr(slot) NULL
 # define rt_hash_lock_init()

where NULL has no type. The solution for the build problem would have 
been to cast the NULL to spinlock_t *, but we need this spinlock so the 
correct solution was to add a || defined(PREEMPT_RT) to the #if 
defined(CONFIG_SMP) line above. Solving the build problem alone only 
fixes the symptom, not the bug.

	Ingo

Re: [patch] IPV4 spinlock_casting

[Ingo Molnar]

* Ingo Molnar <mingo@elte.hu> wrote:

> > Fix a compile error in net/ipv4/route.c when RT patch is applied:
> 
> > Index: linux-2.6.13-rc4-RT-V0.7.52-14/net/ipv4/route.c
> 
> are you sure you are seeing this with the -52-14 patch? If yes then 
> please send me your .config.
> 
> the build error showed a more fundamental bug, which had to be solved 
> differently. The problem was the code in route.c, the problem was this:
> 
>  # define rt_hash_lock_addr(slot) NULL
>  # define rt_hash_lock_init()
> 
> where NULL has no type. The solution for the build problem would have 
> been to cast the NULL to spinlock_t *, but we need this spinlock so 
> the correct solution was to add a || defined(PREEMPT_RT) to the #if 
> defined(CONFIG_SMP) line above. Solving the build problem alone only 
> fixes the symptom, not the bug.

it just occured to me that !PREEMPT_RT builds would be affected by the
#else branch, so i committed the build fix below into -52-15.

	Ingo

Index: linux/net/ipv4/route.c
===================================================================
--- linux.orig/net/ipv4/route.c
+++ linux/net/ipv4/route.c
@@ -231,7 +231,7 @@ static spinlock_t	*rt_hash_locks;
 			spin_lock_init(&rt_hash_locks[i]); \
 		}
 #else
-# define rt_hash_lock_addr(slot) NULL
+# define rt_hash_lock_addr(slot) ((spinlock_t *)NULL)
 # define rt_hash_lock_init()
 #endif
 

Re: [patch] IPV4 spinlock_casting

[Sven-Thorsten Dietrich]

On Mon, 2005-08-08 at 11:06 +0200, Ingo Molnar wrote:
> 
> it just occured to me that !PREEMPT_RT builds would be affected by the
> #else branch, so i committed the build fix below into -52-15.
> 
>         Ingo
> 

That fixes it. Thanks

Sven

> Index: linux/net/ipv4/route.c
> ===================================================================
> --- linux.orig/net/ipv4/route.c
> +++ linux/net/ipv4/route.c
> @@ -231,7 +231,7 @@ static spinlock_t   *rt_hash_locks;
>                         spin_lock_init(&rt_hash_locks[i]); \
>                 }
>  #else
> -# define rt_hash_lock_addr(slot) NULL
> +# define rt_hash_lock_addr(slot) ((spinlock_t *)NULL)
>  # define rt_hash_lock_init()
>  #endif
>  
>