Re: Realtime Preemption, 2.6.12, Beginners Guide?

[Ingo Molnar <mingo@elte.hu>]

> (gdb) ####################################
> (gdb) # c02decd6, stack size:  460 bytes #
> (gdb) ####################################
> (gdb) 0xc02decd6 is in ip_getsockopt (net/ipv4/ip_sockglue.c:877).

----
this patch reduces the stack footprint of ip_getsockopt() from 460 bytes 
to 188 bytes. (note: needs review & testing because i did not excercise 
this multicast codepath.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

Index: linux/net/ipv4/ip_sockglue.c
===================================================================
--- linux.orig/net/ipv4/ip_sockglue.c
+++ linux/net/ipv4/ip_sockglue.c
@@ -1006,20 +1024,28 @@ int ip_getsockopt(struct sock *sk, int l
 		}
 		case MCAST_MSFILTER:
 		{
-			struct group_filter gsf;
+			struct group_filter *gsf;
 			int err;
 
+			gsf = kmalloc(sizeof(*gsf), GFP_KERNEL);
+			if (!gsf) {
+				release_sock(sk);
+				return -ENOMEM;
+			}
 			if (len < GROUP_FILTER_SIZE(0)) {
 				release_sock(sk);
+				kfree(gsf);
 				return -EINVAL;
 			}
-			if (copy_from_user(&gsf, optval, GROUP_FILTER_SIZE(0))) {
+			if (copy_from_user(gsf, optval, GROUP_FILTER_SIZE(0))) {
 				release_sock(sk);
+				kfree(gsf);
 				return -EFAULT;
 			}
-			err = ip_mc_gsfget(sk, &gsf,
+			err = ip_mc_gsfget(sk, gsf,
 				(struct group_filter __user *)optval, optlen);
 			release_sock(sk);
+			kfree(gsf);
 			return err;
 		}
 		case IP_PKTOPTIONS:		
-
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