diff options
Diffstat (limited to 'ipc/msg.c')
| -rw-r--r-- | ipc/msg.c | 44 |
1 files changed, 30 insertions, 14 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index 558aa91186b..245db1140ad 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -253,8 +253,14 @@ static void expunge_all(struct msg_queue *msq, int res) struct msg_receiver *msr, *t; list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { - msr->r_msg = NULL; + msr->r_msg = NULL; /* initialize expunge ordering */ wake_up_process(msr->r_tsk); + /* + * Ensure that the wakeup is visible before setting r_msg as + * the receiving end depends on it: either spinning on a nil, + * or dealing with -EAGAIN cases. See lockless receive part 1 + * and 2 in do_msgrcv(). + */ smp_mb(); msr->r_msg = ERR_PTR(res); } @@ -318,7 +324,7 @@ SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) static inline unsigned long copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) { - switch(version) { + switch (version) { case IPC_64: return copy_to_user(buf, in, sizeof(*in)); case IPC_OLD: @@ -363,7 +369,7 @@ copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) static inline unsigned long copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) { - switch(version) { + switch (version) { case IPC_64: if (copy_from_user(out, buf, sizeof(*out))) return -EFAULT; @@ -375,9 +381,9 @@ copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) return -EFAULT; - out->msg_perm.uid = tbuf_old.msg_perm.uid; - out->msg_perm.gid = tbuf_old.msg_perm.gid; - out->msg_perm.mode = tbuf_old.msg_perm.mode; + out->msg_perm.uid = tbuf_old.msg_perm.uid; + out->msg_perm.gid = tbuf_old.msg_perm.gid; + out->msg_perm.mode = tbuf_old.msg_perm.mode; if (tbuf_old.msg_qbytes == 0) out->msg_qbytes = tbuf_old.msg_lqbytes; @@ -606,13 +612,13 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) static int testmsg(struct msg_msg *msg, long type, int mode) { - switch(mode) + switch (mode) { case SEARCH_ANY: case SEARCH_NUMBER: return 1; case SEARCH_LESSEQUAL: - if (msg->m_type <=type) + if (msg->m_type <= type) return 1; break; case SEARCH_EQUAL: @@ -638,15 +644,22 @@ static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg) list_del(&msr->r_list); if (msr->r_maxsize < msg->m_ts) { + /* initialize pipelined send ordering */ msr->r_msg = NULL; wake_up_process(msr->r_tsk); - smp_mb(); + smp_mb(); /* see barrier comment below */ msr->r_msg = ERR_PTR(-E2BIG); } else { msr->r_msg = NULL; msq->q_lrpid = task_pid_vnr(msr->r_tsk); msq->q_rtime = get_seconds(); wake_up_process(msr->r_tsk); + /* + * Ensure that the wakeup is visible before + * setting r_msg, as the receiving end depends + * on it. See lockless receive part 1 and 2 in + * do_msgrcv(). + */ smp_mb(); msr->r_msg = msg; @@ -654,6 +667,7 @@ static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg) } } } + return 0; } @@ -696,7 +710,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, goto out_unlock0; /* raced with RMID? */ - if (msq->q_perm.deleted) { + if (!ipc_valid_object(&msq->q_perm)) { err = -EIDRM; goto out_unlock0; } @@ -716,6 +730,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, goto out_unlock0; } + /* enqueue the sender and prepare to block */ ss_add(msq, &s); if (!ipc_rcu_getref(msq)) { @@ -731,7 +746,8 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, ipc_lock_object(&msq->q_perm); ipc_rcu_putref(msq, ipc_rcu_free); - if (msq->q_perm.deleted) { + /* raced with RMID? */ + if (!ipc_valid_object(&msq->q_perm)) { err = -EIDRM; goto out_unlock0; } @@ -909,7 +925,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgfl ipc_lock_object(&msq->q_perm); /* raced with RMID? */ - if (msq->q_perm.deleted) { + if (!ipc_valid_object(&msq->q_perm)) { msg = ERR_PTR(-EIDRM); goto out_unlock0; } @@ -983,7 +999,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgfl * wake_up_process(). There is a race with exit(), see * ipc/mqueue.c for the details. */ - msg = (struct msg_msg*)msr_d.r_msg; + msg = (struct msg_msg *)msr_d.r_msg; while (msg == NULL) { cpu_relax(); msg = (struct msg_msg *)msr_d.r_msg; @@ -1004,7 +1020,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgfl /* Lockless receive, part 4: * Repeat test after acquiring the spinlock. */ - msg = (struct msg_msg*)msr_d.r_msg; + msg = (struct msg_msg *)msr_d.r_msg; if (msg != ERR_PTR(-EAGAIN)) goto out_unlock0; |