From patchwork Thu Jun 3 08:01:00 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Henrik Rydberg X-Patchwork-Id: 104052 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter.kernel.org (8.14.3/8.14.3) with ESMTP id o5383tVw018695 for ; Thu, 3 Jun 2010 08:03:55 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757653Ab0FCICN (ORCPT ); Thu, 3 Jun 2010 04:02:13 -0400 Received: from ch-smtp02.sth.basefarm.net ([80.76.149.213]:52345 "EHLO ch-smtp02.sth.basefarm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757973Ab0FCICI (ORCPT ); Thu, 3 Jun 2010 04:02:08 -0400 Received: from c83-248-196-134.bredband.comhem.se ([83.248.196.134]:38567 helo=alnilam) by ch-smtp02.sth.basefarm.net with smtp (Exim 4.68) (envelope-from ) id 1OK5Mo-0000lH-9d; Thu, 03 Jun 2010 10:01:34 +0200 Received: by alnilam (sSMTP sendmail emulation); Thu, 03 Jun 2010 10:01:30 +0200 From: "Henrik Rydberg" To: Dmitry Torokhov Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Jiri Kosina , Mika Kuoppala , Benjamin Tissoires , Rafi Rubin , Henrik Rydberg Subject: [PATCH 2/4] input: evdev: Use multi-reader buffer to save space (rev3) Date: Thu, 3 Jun 2010 10:01:00 +0200 Message-Id: <1275552062-8153-3-git-send-email-rydberg@euromail.se> X-Mailer: git-send-email 1.6.3.3 In-Reply-To: <1275552062-8153-2-git-send-email-rydberg@euromail.se> References: <1275552062-8153-1-git-send-email-rydberg@euromail.se> <1275552062-8153-2-git-send-email-rydberg@euromail.se> X-Originating-IP: 83.248.196.134 X-Scan-Result: No virus found in message 1OK5Mo-0000lH-9d. X-Scan-Signature: ch-smtp02.sth.basefarm.net 1OK5Mo-0000lH-9d 0fe30b1dd082e2e883eae6f6d73fb906 Sender: linux-input-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Thu, 03 Jun 2010 08:03:55 +0000 (UTC) diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index 2ee6c7a..7f0c7da 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -21,6 +21,7 @@ #include #include #include "input-compat.h" +#include "buflock.h" struct evdev { int exist; @@ -33,13 +34,13 @@ struct evdev { spinlock_t client_lock; /* protects client_list */ struct mutex mutex; struct device dev; + struct buflock_writer writer; + struct input_event buffer[EVDEV_BUFFER_SIZE]; }; struct evdev_client { - struct input_event buffer[EVDEV_BUFFER_SIZE]; - int head; - int tail; - spinlock_t buffer_lock; /* protects access to buffer, head and tail */ + struct buflock_reader reader; + spinlock_t entry_lock; /* protects reentrant fops reads */ struct fasync_struct *fasync; struct evdev *evdev; struct list_head node; @@ -48,18 +49,12 @@ struct evdev_client { static struct evdev *evdev_table[EVDEV_MINORS]; static DEFINE_MUTEX(evdev_table_mutex); -static void evdev_pass_event(struct evdev_client *client, - struct input_event *event) +static inline void evdev_sync_event(struct evdev_client *client, + struct evdev *evdev, int type) { - /* - * Interrupts are disabled, just acquire the lock - */ - spin_lock(&client->buffer_lock); - client->buffer[client->head++] = *event; - client->head &= EVDEV_BUFFER_SIZE - 1; - spin_unlock(&client->buffer_lock); - - if (event->type == EV_SYN) + /* sync reader, no locks required */ + buflock_sync_reader(client->reader, evdev->writer); + if (type == EV_SYN) kill_fasync(&client->fasync, SIGIO, POLL_IN); } @@ -78,14 +73,17 @@ static void evdev_event(struct input_handle *handle, event.code = code; event.value = value; + /* lock-less write */ + buflock_write(evdev->writer, evdev->buffer, EVDEV_BUFFER_SIZE, event); + rcu_read_lock(); client = rcu_dereference(evdev->grab); if (client) - evdev_pass_event(client, &event); + evdev_sync_event(client, evdev, type); else list_for_each_entry_rcu(client, &evdev->client_list, node) - evdev_pass_event(client, &event); + evdev_sync_event(client, evdev, type); rcu_read_unlock(); @@ -269,7 +267,7 @@ static int evdev_open(struct inode *inode, struct file *file) goto err_put_evdev; } - spin_lock_init(&client->buffer_lock); + spin_lock_init(&client->entry_lock); client->evdev = evdev; evdev_attach_client(evdev, client); @@ -325,19 +323,19 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer, } static int evdev_fetch_next_event(struct evdev_client *client, + struct evdev *evdev, struct input_event *event) { int have_event; - spin_lock_irq(&client->buffer_lock); + spin_lock_irq(&client->entry_lock); - have_event = client->head != client->tail; - if (have_event) { - *event = client->buffer[client->tail++]; - client->tail &= EVDEV_BUFFER_SIZE - 1; - } + have_event = !buflock_reader_empty(client->reader); + if (have_event) + buflock_read(client->reader, evdev->writer, + evdev->buffer, EVDEV_BUFFER_SIZE, *event); - spin_unlock_irq(&client->buffer_lock); + spin_unlock_irq(&client->entry_lock); return have_event; } @@ -353,12 +351,12 @@ static ssize_t evdev_read(struct file *file, char __user *buffer, if (count < input_event_size()) return -EINVAL; - if (client->head == client->tail && evdev->exist && + if (buflock_reader_empty(client->reader) && evdev->exist && (file->f_flags & O_NONBLOCK)) return -EAGAIN; retval = wait_event_interruptible(evdev->wait, - client->head != client->tail || !evdev->exist); + !buflock_reader_empty(client->reader) || !evdev->exist); if (retval) return retval; @@ -366,7 +364,7 @@ static ssize_t evdev_read(struct file *file, char __user *buffer, return -ENODEV; while (retval + input_event_size() <= count && - evdev_fetch_next_event(client, &event)) { + evdev_fetch_next_event(client, evdev, &event)) { if (input_event_to_user(buffer + retval, &event)) return -EFAULT; @@ -384,7 +382,8 @@ static unsigned int evdev_poll(struct file *file, poll_table *wait) struct evdev *evdev = client->evdev; poll_wait(file, &evdev->wait, wait); - return ((client->head == client->tail) ? 0 : (POLLIN | POLLRDNORM)) | + return (buflock_reader_empty(client->reader) ? 0 : + (POLLIN | POLLRDNORM)) | (evdev->exist ? 0 : (POLLHUP | POLLERR)); }