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-rw-r--r--ipc/msg.c53
1 files changed, 43 insertions, 10 deletions
diff --git a/ipc/msg.c b/ipc/msg.c
index 3c44bbcc05f6..e12307d0c920 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -58,6 +58,7 @@ struct msg_receiver {
struct msg_sender {
struct list_head list;
struct task_struct *tsk;
+ size_t msgsz;
};
#define SEARCH_ANY 1
@@ -153,27 +154,60 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
return msq->q_perm.id;
}
-static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
+static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
+{
+ return msgsz + msq->q_cbytes <= msq->q_qbytes &&
+ 1 + msq->q_qnum <= msq->q_qbytes;
+}
+
+static inline void ss_add(struct msg_queue *msq,
+ struct msg_sender *mss, size_t msgsz)
{
mss->tsk = current;
+ mss->msgsz = msgsz;
__set_current_state(TASK_INTERRUPTIBLE);
list_add_tail(&mss->list, &msq->q_senders);
}
static inline void ss_del(struct msg_sender *mss)
{
- if (mss->list.next != NULL)
+ if (mss->list.next)
list_del(&mss->list);
}
-static void ss_wakeup(struct list_head *h,
+static void ss_wakeup(struct msg_queue *msq,
struct wake_q_head *wake_q, bool kill)
{
struct msg_sender *mss, *t;
+ struct task_struct *stop_tsk = NULL;
+ struct list_head *h = &msq->q_senders;
list_for_each_entry_safe(mss, t, h, list) {
if (kill)
mss->list.next = NULL;
+
+ /*
+ * Stop at the first task we don't wakeup,
+ * we've already iterated the original
+ * sender queue.
+ */
+ else if (stop_tsk == mss->tsk)
+ break;
+ /*
+ * We are not in an EIDRM scenario here, therefore
+ * verify that we really need to wakeup the task.
+ * To maintain current semantics and wakeup order,
+ * move the sender to the tail on behalf of the
+ * blocked task.
+ */
+ else if (!msg_fits_inqueue(msq, mss->msgsz)) {
+ if (!stop_tsk)
+ stop_tsk = mss->tsk;
+
+ list_move_tail(&mss->list, &msq->q_senders);
+ continue;
+ }
+
wake_q_add(wake_q, mss->tsk);
}
}
@@ -204,7 +238,7 @@ static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
WAKE_Q(wake_q);
expunge_all(msq, -EIDRM, &wake_q);
- ss_wakeup(&msq->q_senders, &wake_q, true);
+ ss_wakeup(msq, &wake_q, true);
msg_rmid(ns, msq);
ipc_unlock_object(&msq->q_perm);
wake_up_q(&wake_q);
@@ -388,7 +422,7 @@ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
* Sleeping senders might be able to send
* due to a larger queue size.
*/
- ss_wakeup(&msq->q_senders, &wake_q, false);
+ ss_wakeup(msq, &wake_q, false);
ipc_unlock_object(&msq->q_perm);
wake_up_q(&wake_q);
@@ -642,10 +676,8 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext,
if (err)
goto out_unlock0;
- if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
- 1 + msq->q_qnum <= msq->q_qbytes) {
+ if (msg_fits_inqueue(msq, msgsz))
break;
- }
/* queue full, wait: */
if (msgflg & IPC_NOWAIT) {
@@ -654,7 +686,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext,
}
/* enqueue the sender and prepare to block */
- ss_add(msq, &s);
+ ss_add(msq, &s, msgsz);
if (!ipc_rcu_getref(msq)) {
err = -EIDRM;
@@ -682,6 +714,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext,
}
}
+
msq->q_lspid = task_tgid_vnr(current);
msq->q_stime = get_seconds();
@@ -882,7 +915,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgfl
msq->q_cbytes -= msg->m_ts;
atomic_sub(msg->m_ts, &ns->msg_bytes);
atomic_dec(&ns->msg_hdrs);
- ss_wakeup(&msq->q_senders, &wake_q, false);
+ ss_wakeup(msq, &wake_q, false);
goto out_unlock0;
}

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