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Subject[PATCH 4/4] ipc: add more comments to message copying related code
From
Date
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
---
ipc/msg.c | 8 ++++++++
1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/ipc/msg.c b/ipc/msg.c
index 5e317fe..4a4725c 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -770,6 +770,10 @@ static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
}

#ifdef CONFIG_CHECKPOINT_RESTORE
+/*
+ * This function creates new kernel message structure, large enough to store
+ * bufsz message bytes.
+ */
static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz,
int msgflg, long *msgtyp,
unsigned long *copy_number)
@@ -881,6 +885,10 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
msg = ERR_PTR(-E2BIG);
goto out_unlock;
}
+ /*
+ * If we are copying, then do not unlink message and do
+ * not update queue parameters.
+ */
if (msgflg & MSG_COPY)
goto out_unlock;
list_del(&msg->m_list);


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