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Subject[take21 2/4] kevent: poll/select() notifications.
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poll/select() notifications.

This patch includes generic poll/select notifications.
kevent_poll works simialr to epoll and has the same issues (callback
is invoked not from internal state machine of the caller, but through
process awake, a lot of allocations and so on).

Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mitp.ru>

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5baf3a1..f81299f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -276,6 +276,7 @@ #include <linux/prio_tree.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/mutex.h>
+#include <linux/kevent.h>

#include <asm/atomic.h>
#include <asm/semaphore.h>
@@ -586,6 +587,10 @@ #ifdef CONFIG_INOTIFY
struct mutex inotify_mutex; /* protects the watches list */
#endif

+#ifdef CONFIG_KEVENT_SOCKET
+ struct kevent_storage st;
+#endif
+
unsigned long i_state;
unsigned long dirtied_when; /* jiffies of first dirtying */

@@ -739,6 +744,9 @@ #ifdef CONFIG_EPOLL
struct list_head f_ep_links;
spinlock_t f_ep_lock;
#endif /* #ifdef CONFIG_EPOLL */
+#ifdef CONFIG_KEVENT_POLL
+ struct kevent_storage st;
+#endif
struct address_space *f_mapping;
};
extern spinlock_t files_lock;
diff --git a/kernel/kevent/kevent_poll.c b/kernel/kevent/kevent_poll.c
new file mode 100644
index 0000000..fb74e0f
--- /dev/null
+++ b/kernel/kevent/kevent_poll.c
@@ -0,0 +1,222 @@
+/*
+ * 2006 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/file.h>
+#include <linux/kevent.h>
+#include <linux/poll.h>
+#include <linux/fs.h>
+
+static kmem_cache_t *kevent_poll_container_cache;
+static kmem_cache_t *kevent_poll_priv_cache;
+
+struct kevent_poll_ctl
+{
+ struct poll_table_struct pt;
+ struct kevent *k;
+};
+
+struct kevent_poll_wait_container
+{
+ struct list_head container_entry;
+ wait_queue_head_t *whead;
+ wait_queue_t wait;
+ struct kevent *k;
+};
+
+struct kevent_poll_private
+{
+ struct list_head container_list;
+ spinlock_t container_lock;
+};
+
+static int kevent_poll_enqueue(struct kevent *k);
+static int kevent_poll_dequeue(struct kevent *k);
+static int kevent_poll_callback(struct kevent *k);
+
+static int kevent_poll_wait_callback(wait_queue_t *wait,
+ unsigned mode, int sync, void *key)
+{
+ struct kevent_poll_wait_container *cont =
+ container_of(wait, struct kevent_poll_wait_container, wait);
+ struct kevent *k = cont->k;
+ struct file *file = k->st->origin;
+ u32 revents;
+
+ revents = file->f_op->poll(file, NULL);
+
+ kevent_storage_ready(k->st, NULL, revents);
+
+ return 0;
+}
+
+static void kevent_poll_qproc(struct file *file, wait_queue_head_t *whead,
+ struct poll_table_struct *poll_table)
+{
+ struct kevent *k =
+ container_of(poll_table, struct kevent_poll_ctl, pt)->k;
+ struct kevent_poll_private *priv = k->priv;
+ struct kevent_poll_wait_container *cont;
+ unsigned long flags;
+
+ cont = kmem_cache_alloc(kevent_poll_container_cache, SLAB_KERNEL);
+ if (!cont) {
+ kevent_break(k);
+ return;
+ }
+
+ cont->k = k;
+ init_waitqueue_func_entry(&cont->wait, kevent_poll_wait_callback);
+ cont->whead = whead;
+
+ spin_lock_irqsave(&priv->container_lock, flags);
+ list_add_tail(&cont->container_entry, &priv->container_list);
+ spin_unlock_irqrestore(&priv->container_lock, flags);
+
+ add_wait_queue(whead, &cont->wait);
+}
+
+static int kevent_poll_enqueue(struct kevent *k)
+{
+ struct file *file;
+ int err, ready = 0;
+ unsigned int revents;
+ struct kevent_poll_ctl ctl;
+ struct kevent_poll_private *priv;
+
+ file = fget(k->event.id.raw[0]);
+ if (!file)
+ return -ENODEV;
+
+ err = -EINVAL;
+ if (!file->f_op || !file->f_op->poll)
+ goto err_out_fput;
+
+ err = -ENOMEM;
+ priv = kmem_cache_alloc(kevent_poll_priv_cache, SLAB_KERNEL);
+ if (!priv)
+ goto err_out_fput;
+
+ spin_lock_init(&priv->container_lock);
+ INIT_LIST_HEAD(&priv->container_list);
+
+ k->priv = priv;
+
+ ctl.k = k;
+ init_poll_funcptr(&ctl.pt, &kevent_poll_qproc);
+
+ err = kevent_storage_enqueue(&file->st, k);
+ if (err)
+ goto err_out_free;
+
+ revents = file->f_op->poll(file, &ctl.pt);
+ if (revents & k->event.event) {
+ ready = 1;
+ kevent_poll_dequeue(k);
+ }
+
+ return ready;
+
+err_out_free:
+ kmem_cache_free(kevent_poll_priv_cache, priv);
+err_out_fput:
+ fput(file);
+ return err;
+}
+
+static int kevent_poll_dequeue(struct kevent *k)
+{
+ struct file *file = k->st->origin;
+ struct kevent_poll_private *priv = k->priv;
+ struct kevent_poll_wait_container *w, *n;
+ unsigned long flags;
+
+ kevent_storage_dequeue(k->st, k);
+
+ spin_lock_irqsave(&priv->container_lock, flags);
+ list_for_each_entry_safe(w, n, &priv->container_list, container_entry) {
+ list_del(&w->container_entry);
+ remove_wait_queue(w->whead, &w->wait);
+ kmem_cache_free(kevent_poll_container_cache, w);
+ }
+ spin_unlock_irqrestore(&priv->container_lock, flags);
+
+ kmem_cache_free(kevent_poll_priv_cache, priv);
+ k->priv = NULL;
+
+ fput(file);
+
+ return 0;
+}
+
+static int kevent_poll_callback(struct kevent *k)
+{
+ struct file *file = k->st->origin;
+ unsigned int revents = file->f_op->poll(file, NULL);
+
+ k->event.ret_data[0] = revents & k->event.event;
+
+ return (revents & k->event.event);
+}
+
+static int __init kevent_poll_sys_init(void)
+{
+ struct kevent_callbacks pc = {
+ .callback = &kevent_poll_callback,
+ .enqueue = &kevent_poll_enqueue,
+ .dequeue = &kevent_poll_dequeue};
+
+ kevent_poll_container_cache = kmem_cache_create("kevent_poll_container_cache",
+ sizeof(struct kevent_poll_wait_container), 0, 0, NULL, NULL);
+ if (!kevent_poll_container_cache) {
+ printk(KERN_ERR "Failed to create kevent poll container cache.\n");
+ return -ENOMEM;
+ }
+
+ kevent_poll_priv_cache = kmem_cache_create("kevent_poll_priv_cache",
+ sizeof(struct kevent_poll_private), 0, 0, NULL, NULL);
+ if (!kevent_poll_priv_cache) {
+ printk(KERN_ERR "Failed to create kevent poll private data cache.\n");
+ kmem_cache_destroy(kevent_poll_container_cache);
+ kevent_poll_container_cache = NULL;
+ return -ENOMEM;
+ }
+
+ kevent_add_callbacks(&pc, KEVENT_POLL);
+
+ printk(KERN_INFO "Kevent poll()/select() subsystem has been initialized.\n");
+ return 0;
+}
+
+static struct lock_class_key kevent_poll_key;
+
+void kevent_poll_reinit(struct file *file)
+{
+ lockdep_set_class(&file->st.lock, &kevent_poll_key);
+}
+
+static void __exit kevent_poll_sys_fini(void)
+{
+ kmem_cache_destroy(kevent_poll_priv_cache);
+ kmem_cache_destroy(kevent_poll_container_cache);
+}
+
+module_init(kevent_poll_sys_init);
+module_exit(kevent_poll_sys_fini);
-
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