[RFC][PATCH -mm] Add genetlink utilities for payload length calculation

[RFC][PATCH -mm] Add genetlink utilities for payload length calculation

[Balbir Singh]

Add two utility helper functions genlmsg_msg_size() and genlmsg_total_size().
These functions are derived from their netlink counterparts.

Signed-off-by: Balbir Singh <balbir@in.ibm.com>
---

 include/net/genetlink.h |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+)

diff -puN include/net/genetlink.h~genetlink-payload-size-helpers include/net/genetlink.h
--- linux-2.6.18-rc6/include/net/genetlink.h~genetlink-payload-size-helpers	2006-09-11 10:34:56.000000000 +0530
+++ linux-2.6.18-rc6-balbir/include/net/genetlink.h	2006-09-11 11:42:37.000000000 +0530
@@ -171,4 +171,22 @@ static inline int genlmsg_len(const stru
 	return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN);
 }
 
+/**
+ * genlmsg_msg_size - length of genetlink message not including padding
+ * @payload: length of message payload
+ */
+static inline int genlmsg_msg_size(int payload)
+{
+	return GENL_HDRLEN + payload;
+}
+
+/**
+ * genlmsg_total_size - length of genetlink message including padding
+ * @payload: length of message payload
+ */
+static inline int genlmsg_total_size(int payload)
+{
+	return NLMSG_ALIGN(genlmsg_msg_size(payload));
+}
+
 #endif	/* __NET_GENERIC_NETLINK_H */
_

-- 

	Balbir Singh,
	Linux Technology Center,
	IBM Software Labs

[RFC][PATCH -mm] Fix taskstats size calculation (use the new genetlink utility functions)

[Balbir Singh]

The addition of the CSA patch pushed the size of struct taskstats to 256
bytes. This exposed a problem with prepare_reply(), we were not allocating
space for the netlink and genetlink header. It worked earlier because
alloc_skb() would align the skb to SMP_CACHE_BYTES, which added some additonal
bytes.

Signed-off-by: Balbir Singh <balbir@in.ibm.com>
---

 kernel/taskstats.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -puN kernel/taskstats.c~taskstats-fix-msg-size kernel/taskstats.c
--- linux-2.6.18-rc6/kernel/taskstats.c~taskstats-fix-msg-size	2006-09-11 11:42:40.000000000 +0530
+++ linux-2.6.18-rc6-balbir/kernel/taskstats.c	2006-09-11 11:42:55.000000000 +0530
@@ -77,7 +77,7 @@ static int prepare_reply(struct genl_inf
 	/*
 	 * If new attributes are added, please revisit this allocation
 	 */
-	skb = nlmsg_new(size, GFP_KERNEL);
+	skb = nlmsg_new(genlmsg_total_size(size), GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
_

-- 

	Balbir Singh,
	Linux Technology Center,
	IBM Software Labs

[RFC][PATCH -mm] Fix getdelays.c - cpumask length and error reporting.

[Balbir Singh]

Fix the length passed while (un)registering cpumask. We were passing
sizeof the array, make it strlen().

Error value printed in fatal errors should be derived from the message.
The message contains an nlmsgerr embedded with an error value. We must
report that value to the user.

Signed-off-by: Balbir Singh <balbir@in.ibm.com>
---

 Documentation/accounting/getdelays.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff -puN Documentation/accounting/getdelays.c~taskstats-fix-delayacct-utility Documentation/accounting/getdelays.c
--- linux-2.6.18-rc6/Documentation/accounting/getdelays.c~taskstats-fix-delayacct-utility	2006-09-11 12:43:50.000000000 +0530
+++ linux-2.6.18-rc6-balbir/Documentation/accounting/getdelays.c	2006-09-11 12:46:57.000000000 +0530
@@ -285,7 +285,7 @@ int main(int argc, char *argv[])
 	if (maskset) {
 		rc = send_cmd(nl_sd, id, mypid, TASKSTATS_CMD_GET,
 			      TASKSTATS_CMD_ATTR_REGISTER_CPUMASK,
-			      &cpumask, sizeof(cpumask));
+			      &cpumask, strlen(cpumask) + 1);
 		PRINTF("Sent register cpumask, retval %d\n", rc);
 		if (rc < 0) {
 			printf("error sending register cpumask\n");
@@ -315,7 +315,8 @@ int main(int argc, char *argv[])
 		}
 		if (msg.n.nlmsg_type == NLMSG_ERROR ||
 		    !NLMSG_OK((&msg.n), rep_len)) {
-			printf("fatal reply error,  errno %d\n", errno);
+			struct nlmsgerr *err = NLMSG_DATA(&msg);
+			printf("fatal reply error,  errno %d\n", err->error);
 			goto done;
 		}
 
@@ -383,7 +384,7 @@ done:
 	if (maskset) {
 		rc = send_cmd(nl_sd, id, mypid, TASKSTATS_CMD_GET,
 			      TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK,
-			      &cpumask, sizeof(cpumask));
+			      &cpumask, strlen(cpumask) + 1);
 		printf("Sent deregister mask, retval %d\n", rc);
 		if (rc < 0)
 			err(rc, "error sending deregister cpumask\n");
_

-- 

	Balbir Singh,
	Linux Technology Center,
	IBM Software Labs