From: Manfred Spraul <manfred@colorfullife.com>
Linux specific extension: make the message queue identifiers pollable. It's
simple and could be useful.
---
ipc/mqueue.c | 27 ++++++++++++++++++++++++---
1 files changed, 24 insertions(+), 3 deletions(-)
diff -puN ipc/mqueue.c~mq-04-linuxext-poll ipc/mqueue.c
--- 25/ipc/mqueue.c~mq-04-linuxext-poll 2004-02-29 02:12:44.000000000 -0800
+++ 25-akpm/ipc/mqueue.c 2004-02-29 02:12:44.000000000 -0800
@@ -251,6 +251,24 @@ static int mqueue_flush_file(struct file
return 0;
}
+static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
+{
+ struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
+ int retval = 0;
+
+ poll_wait(filp, &info->wait_q, poll_tab);
+
+ spin_lock(&info->lock);
+ if (info->attr.mq_curmsgs)
+ retval = POLLIN | POLLRDNORM;
+
+ if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
+ retval |= POLLOUT | POLLWRNORM;
+ spin_unlock(&info->lock);
+
+ return retval;
+}
+
/* Adds current to info->e_wait_q[sr] before element with smaller prio */
static void wq_add(struct mqueue_inode_info *info, int sr,
struct ext_wait_queue *ewp)
@@ -376,11 +394,11 @@ static void __do_notify(struct mqueue_in
&sig_i, info->notify_owner);
} else if (info->notify.sigev_notify == SIGEV_THREAD) {
info->notify_filp->private_data = (void*)NP_WOKENUP;
- wake_up(&info->wait_q);
}
/* after notification unregisters process */
info->notify_owner = 0;
}
+ wake_up(&info->wait_q);
}
static long prepare_timeout(const struct timespec __user *u_arg)
@@ -712,9 +730,11 @@ static inline void pipelined_receive(str
{
struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
- if (!sender)
+ if (!sender) {
+ /* for poll */
+ wake_up_interruptible(&info->wait_q);
return;
-
+ }
msg_insert(sender->msg, info);
list_del(&sender->list);
sender->state = STATE_PENDING;
@@ -1035,6 +1055,7 @@ static struct inode_operations mqueue_di
static struct file_operations mqueue_file_operations = {
.flush = mqueue_flush_file,
+ .poll = mqueue_poll_file,
};
static struct file_operations mqueue_notify_fops = {
_