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From 3e4486b80f54c8a47e8e5952b90f0d6eb47add26 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:30:12 -0500
Subject: [PATCH] ipc: Make the ipc code -rt aware
commit 3c96a21d186d7cadff3e356ecbea8ee9ad2692aa in tip.
RT serializes the code with the (rt)spinlock but keeps preemption
enabled. Some parts of the code need to be atomic
nevertheless.
Protect it with preempt_disable/enable_rt pairts.
[PG: drop ipc/sem.c part; no longer exists in update_queue]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
ipc/mqueue.c | 5 +++++
ipc/msg.c | 16 ++++++++++++++++
2 files changed, 21 insertions(+), 0 deletions(-)
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 59a009d..e039b7f 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -825,12 +825,17 @@ static inline void pipelined_send(struct mqueue_inode_info *info,
struct msg_msg *message,
struct ext_wait_queue *receiver)
{
+ /*
+ * Keep them in one critical section for PREEMPT_RT:
+ */
+ preempt_disable_rt();
receiver->msg = message;
list_del(&receiver->list);
receiver->state = STATE_PENDING;
wake_up_process(receiver->task);
smp_wmb();
receiver->state = STATE_READY;
+ preempt_enable_nort();
}
/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
diff --git a/ipc/msg.c b/ipc/msg.c
index 9547cb7..1891141 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -259,12 +259,20 @@ static void expunge_all(struct msg_queue *msq, int res)
while (tmp != &msq->q_receivers) {
struct msg_receiver *msr;
+ /*
+ * Make sure that the wakeup doesnt preempt
+ * this CPU prematurely. (on PREEMPT_RT)
+ */
+ preempt_disable_rt();
+
msr = list_entry(tmp, struct msg_receiver, r_list);
tmp = tmp->next;
msr->r_msg = NULL;
wake_up_process(msr->r_tsk);
smp_mb();
msr->r_msg = ERR_PTR(res);
+
+ preempt_enable_rt();
}
}
@@ -611,6 +619,12 @@ static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
!security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
msr->r_msgtype, msr->r_mode)) {
+ /*
+ * Make sure that the wakeup doesnt preempt
+ * this CPU prematurely. (on PREEMPT_RT)
+ */
+ preempt_disable_rt();
+
list_del(&msr->r_list);
if (msr->r_maxsize < msg->m_ts) {
msr->r_msg = NULL;
@@ -624,9 +638,11 @@ static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
wake_up_process(msr->r_tsk);
smp_mb();
msr->r_msg = msg;
+ preempt_enable_rt();
return 1;
}
+ preempt_enable_rt();
}
}
return 0;
--
1.7.0.4
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