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authorJohannes Berg <johannes.berg@intel.com>2011-06-20 13:40:46 +0200
committerJohn W. Linville <linville@tuxdriver.com>2011-06-22 16:09:45 -0400
commit670dc2833d144375eac36ad74111495a825a9288 (patch)
tree12d5d3a925da562a6ba0497c47f4b55c71ff545b /include/linux/netlink.h
parentc1c3daee97498f5d74bfd23531cfe23c8e14a619 (diff)
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netlink: advertise incomplete dumps
Consider the following situation: * a dump that would show 8 entries, four in the first round, and four in the second * between the first and second rounds, 6 entries are removed * now the second round will not show any entry, and even if there is a sequence/generation counter the application will not know To solve this problem, add a new flag NLM_F_DUMP_INTR to the netlink header that indicates the dump wasn't consistent, this flag can also be set on the MSG_DONE message that terminates the dump, and as such above situation can be detected. To achieve this, add a sequence counter to the netlink callback struct. Of course, netlink code still needs to use this new functionality. The correct way to do that is to always set cb->seq when a dumpit callback is invoked and call nl_dump_check_consistent() for each new message. The core code will also call this function for the final MSG_DONE message. To make it usable with generic netlink, a new function genlmsg_nlhdr() is needed to obtain the netlink header from the genetlink user header. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'include/linux/netlink.h')
-rw-r--r--include/linux/netlink.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 4c4ac3f3ce5a..8d1bcec5cc06 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -48,6 +48,7 @@ struct nlmsghdr {
#define NLM_F_MULTI 2 /* Multipart message, terminated by NLMSG_DONE */
#define NLM_F_ACK 4 /* Reply with ack, with zero or error code */
#define NLM_F_ECHO 8 /* Echo this request */
+#define NLM_F_DUMP_INTR 16 /* Dump was inconsistent due to sequence change */
/* Modifiers to GET request */
#define NLM_F_ROOT 0x100 /* specify tree root */
@@ -221,6 +222,7 @@ struct netlink_callback {
struct netlink_callback *cb);
int (*done)(struct netlink_callback *cb);
int family;
+ unsigned int prev_seq, seq;
long args[6];
};