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netlink: invert error code in netlink_set_err() 

The callers of netlink_set_err() currently pass a negative value
as parameter for the error code. However, sk->sk_err wants a
positive error value. Without this patch, skb_recv_datagram() called
by netlink_recvmsg() may return a positive value to report an error.

Another choice to fix this is to change callers to pass a positive
error value, but this seems a bit inconsistent and error prone
to me. Indeed, the callers of netlink_set_err() assumed that the
(usual) negative value for error codes was fine before this patch :).

This patch also includes some documentation in docbook format
for netlink_set_err() to avoid this sort of confusion.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pablo Neira Ayuso 2009-03-03 23:37:30 -08:00 committed by David S. Miller
parent 17edde5209
commit 4843b93c96
1 changed files with 9 additions and 1 deletions
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10
net/netlink/af_netlink.c
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@ -1084,6 +1084,13 @@ out:
return 0;
}
/**
* netlink_set_err - report error to broadcast listeners
* @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
* @pid: the PID of a process that we want to skip (if any)
* @groups: the broadcast group that will notice the error
* @code: error code, must be negative (as usual in kernelspace)
*/
void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
{
struct netlink_set_err_data info;
@ -1093,7 +1100,8 @@ void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
info.exclude_sk = ssk;
info.pid = pid;
info.group = group;
info.code = code;
/* sk->sk_err wants a positive error value */
info.code = -code;
read_lock(&nl_table_lock);