Re: [RFC] tcp: setsockopt congestion control autoload
From: John Heffner <hidden>
Date: 2006-10-26 17:29:48
My reservation in doing this would be that as an administrator, I may want to choose exactly what congestion control is available any any given time. The different congestion control algorithms are not necessarily fair to each other. If the modules are autoloaded, I could still enforce this by moving the modules out of /lib/modules, but I think it's cleaner to do it by loading/unloading modules as appropriate. -John Stephen Hemminger wrote:
quoted hunk ↗ jump to hunk
If user asks for a congestion control type with setsockopt() then it may be available as a module not included in the kernel already. It should be autoloaded if needed. This is done already when the default selection is change with sysctl, but not when application requests via sysctl. Only reservation is are there any bad security implications from this? Signed-off-by: Stephen Hemminger <redacted>--- orig/net/ipv4/tcp_cong.c 2006-10-25 13:55:34.000000000 -0700 +++ new/net/ipv4/tcp_cong.c 2006-10-25 13:58:39.000000000 -0700@@ -153,9 +153,19 @@ rcu_read_lock(); ca = tcp_ca_find(name); + /* no change asking for existing value */ if (ca == icsk->icsk_ca_ops) goto out; +#ifdef CONFIG_KMOD + /* not found attempt to autoload module */ + if (!ca) { + rcu_read_unlock(); + request_module("tcp_%s", name); + rcu_read_lock(); + ca = tcp_ca_find(name); + } +#endif if (!ca) err = -ENOENT; -To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html