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authorJeff Mahoney <jeffm@suse.com>2010-10-27 15:34:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-27 18:03:17 -0700
commit85893120699f8bae8caa12a8ee18ab5fceac978e (patch)
tree07fb62d6c8818e8feab72d4bd78b3e4a2bbbb829 /kernel/taskstats.c
parentdb9e5679d6aecb17253f41bd06d98194800f9c01 (diff)
downloadvexpress-lsk-85893120699f8bae8caa12a8ee18ab5fceac978e.tar.gz
delayacct: align to 8 byte boundary on 64-bit systems
prepare_reply() sets up an skb for the response. The payload contains: +--------------------------------+ | genlmsghdr - 4 bytes | +--------------------------------+ | NLA header - 4 bytes | /* Aggregate header */ +-+------------------------------+ | | NLA header - 4 bytes | /* PID header */ | +------------------------------+ | | pid/tgid - 4 bytes | | +------------------------------+ | | NLA header - 4 bytes | /* stats header */ | + -----------------------------+ <- oops. aligned on 4 byte boundary | | struct taskstats - 328 bytes | +-+------------------------------+ The start of the taskstats struct must be 8 byte aligned on IA64 (and other systems with 8 byte alignment rules for 64-bit types) or runtime alignment warnings will be issued. This patch pads the pid/tgid field out to sizeof(long), which forces the alignment of taskstats. The getdelays userspace code is ok with this since it assumes 32-bit pid/tgid and then honors that header's length field. An array is used to avoid exposing kernel memory contents to userspace in the response. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/taskstats.c')
-rw-r--r--kernel/taskstats.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 11281d5792b..5a651aa63d6 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -360,6 +360,12 @@ static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
struct nlattr *na, *ret;
int aggr;
+ /* If we don't pad, we end up with alignment on a 4 byte boundary.
+ * This causes lots of runtime warnings on systems requiring 8 byte
+ * alignment */
+ u32 pids[2] = { pid, 0 };
+ int pid_size = ALIGN(sizeof(pid), sizeof(long));
+
aggr = (type == TASKSTATS_TYPE_PID)
? TASKSTATS_TYPE_AGGR_PID
: TASKSTATS_TYPE_AGGR_TGID;
@@ -367,7 +373,7 @@ static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
na = nla_nest_start(skb, aggr);
if (!na)
goto err;
- if (nla_put(skb, type, sizeof(pid), &pid) < 0)
+ if (nla_put(skb, type, pid_size, pids) < 0)
goto err;
ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
if (!ret)