This is a note to let you know that I've just added the patch titled
USB: cdc-wdm: use two mutexes to allow simultaneous read and write
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-cdc-wdm-use-two-mutexes-to-allow-simultaneous-read-and-write.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From e8537bd2c4f325a4796da33564ddcef9489b7feb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <[email protected]>
Date: Mon, 16 Jan 2012 12:41:48 +0100
Subject: USB: cdc-wdm: use two mutexes to allow simultaneous read and write
MIME-Version: 1.0
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From: Bjørn Mork <[email protected]>
commit e8537bd2c4f325a4796da33564ddcef9489b7feb upstream.
using a separate read and write mutex for locking is sufficient to make the
driver accept simultaneous read and write. This improves useability a lot.
Signed-off-by: Bjørn Mork <[email protected]>
Cc: Oliver Neukum <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/usb/class/cdc-wdm.c | 49 +++++++++++++++++++++++++++-----------------
1 file changed, 31 insertions(+), 18 deletions(-)
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -88,7 +88,8 @@ struct wdm_device {
int count;
dma_addr_t shandle;
dma_addr_t ihandle;
- struct mutex lock;
+ struct mutex wlock;
+ struct mutex rlock;
wait_queue_head_t wait;
struct work_struct rxwork;
int werr;
@@ -323,7 +324,7 @@ static ssize_t wdm_write
}
/* concurrent writes and disconnect */
- r = mutex_lock_interruptible(&desc->lock);
+ r = mutex_lock_interruptible(&desc->wlock);
rv = -ERESTARTSYS;
if (r) {
kfree(buf);
@@ -386,7 +387,7 @@ static ssize_t wdm_write
out:
usb_autopm_put_interface(desc->intf);
outnp:
- mutex_unlock(&desc->lock);
+ mutex_unlock(&desc->wlock);
outnl:
return rv < 0 ? rv : count;
}
@@ -399,7 +400,7 @@ static ssize_t wdm_read
struct wdm_device *desc = file->private_data;
- rv = mutex_lock_interruptible(&desc->lock); /*concurrent reads */
+ rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */
if (rv < 0)
return -ERESTARTSYS;
@@ -476,7 +477,7 @@ retry:
rv = cntr;
err:
- mutex_unlock(&desc->lock);
+ mutex_unlock(&desc->rlock);
return rv;
}
@@ -542,7 +543,8 @@ static int wdm_open(struct inode *inode,
}
intf->needs_remote_wakeup = 1;
- mutex_lock(&desc->lock);
+ /* using write lock to protect desc->count */
+ mutex_lock(&desc->wlock);
if (!desc->count++) {
desc->werr = 0;
desc->rerr = 0;
@@ -555,7 +557,7 @@ static int wdm_open(struct inode *inode,
} else {
rv = 0;
}
- mutex_unlock(&desc->lock);
+ mutex_unlock(&desc->wlock);
usb_autopm_put_interface(desc->intf);
out:
mutex_unlock(&wdm_mutex);
@@ -567,9 +569,11 @@ static int wdm_release(struct inode *ino
struct wdm_device *desc = file->private_data;
mutex_lock(&wdm_mutex);
- mutex_lock(&desc->lock);
+
+ /* using write lock to protect desc->count */
+ mutex_lock(&desc->wlock);
desc->count--;
- mutex_unlock(&desc->lock);
+ mutex_unlock(&desc->wlock);
if (!desc->count) {
dev_dbg(&desc->intf->dev, "wdm_release: cleanup");
@@ -667,7 +671,8 @@ next_desc:
desc = kzalloc(sizeof(struct wdm_device), GFP_KERNEL);
if (!desc)
goto out;
- mutex_init(&desc->lock);
+ mutex_init(&desc->rlock);
+ mutex_init(&desc->wlock);
spin_lock_init(&desc->iuspin);
init_waitqueue_head(&desc->wait);
desc->wMaxCommand = maxcom;
@@ -781,10 +786,12 @@ static void wdm_disconnect(struct usb_in
/* to terminate pending flushes */
clear_bit(WDM_IN_USE, &desc->flags);
spin_unlock_irqrestore(&desc->iuspin, flags);
- mutex_lock(&desc->lock);
+ mutex_lock(&desc->rlock);
+ mutex_lock(&desc->wlock);
kill_urbs(desc);
cancel_work_sync(&desc->rxwork);
- mutex_unlock(&desc->lock);
+ mutex_unlock(&desc->wlock);
+ mutex_unlock(&desc->rlock);
wake_up_all(&desc->wait);
if (!desc->count)
cleanup(desc);
@@ -800,8 +807,10 @@ static int wdm_suspend(struct usb_interf
dev_dbg(&desc->intf->dev, "wdm%d_suspend\n", intf->minor);
/* if this is an autosuspend the caller does the locking */
- if (!(message.event & PM_EVENT_AUTO))
- mutex_lock(&desc->lock);
+ if (!(message.event & PM_EVENT_AUTO)) {
+ mutex_lock(&desc->rlock);
+ mutex_lock(&desc->wlock);
+ }
spin_lock_irq(&desc->iuspin);
if ((message.event & PM_EVENT_AUTO) &&
@@ -817,8 +826,10 @@ static int wdm_suspend(struct usb_interf
kill_urbs(desc);
cancel_work_sync(&desc->rxwork);
}
- if (!(message.event & PM_EVENT_AUTO))
- mutex_unlock(&desc->lock);
+ if (!(message.event & PM_EVENT_AUTO)) {
+ mutex_unlock(&desc->wlock);
+ mutex_unlock(&desc->rlock);
+ }
return rv;
}
@@ -856,7 +867,8 @@ static int wdm_pre_reset(struct usb_inte
{
struct wdm_device *desc = usb_get_intfdata(intf);
- mutex_lock(&desc->lock);
+ mutex_lock(&desc->rlock);
+ mutex_lock(&desc->wlock);
kill_urbs(desc);
/*
@@ -878,7 +890,8 @@ static int wdm_post_reset(struct usb_int
int rv;
rv = recover_from_urb_loss(desc);
- mutex_unlock(&desc->lock);
+ mutex_unlock(&desc->wlock);
+ mutex_unlock(&desc->rlock);
return 0;
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/usb-cdc-wdm-use-two-mutexes-to-allow-simultaneous-read-and-write.patch
queue-3.0/usb-cdc-wdm-updating-desc-length-must-be-protected-by-spin_lock.patch
--
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