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Date: Sat, 26 Jan 2008 12:00:41 +0530
From: Romit Dasgupta <romlinux@...il.com>
To: greg@...ah.com, stern@...land.harvard.edu,
linux-usb@...r.kernel.org, dbrownell@...rs.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] Moving spinlock to struct usb_hcd
Hi,
This is an attempt to move the hcd_urb_list_lock to struct usb_hcd.
The lock is taken on functions that try to add/delete/use urb against a
given hcd. I have not seen any association of an urb with multiple hcds.
Hence I thought this can be moved within usb_hcd. This should help
reduce contention to usb during high load where i/o is happening to
multiple hcds. I am also trying to see if hcd_root_hub_lock can also be
moved to usb_hcd. Any comments on this? I have done some testing with
this patch and it seems to be holding fine. If this looks ok I will
submit the lock statistics before and after the change.
Thanks,
-Romit
---
drivers/usb/core/hcd.c | 24 +++++++++++-------------
drivers/usb/core/hcd.h | 1 +
2 files changed, 12 insertions(+), 13 deletions(-)
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index d5ed3fa..6eb0f45 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -98,9 +98,6 @@ EXPORT_SYMBOL_GPL (usb_bus_list_lock);
/* used for controlling access to virtual root hubs */
static DEFINE_SPINLOCK(hcd_root_hub_lock);
-/* used when updating an endpoint's URB list */
-static DEFINE_SPINLOCK(hcd_urb_list_lock);
-
/* wait queue for synchronous unlinks */
DECLARE_WAIT_QUEUE_HEAD(usb_kill_urb_queue);
@@ -1000,7 +997,7 @@ int usb_hcd_link_urb_to_ep(struct usb_hcd *hcd,
struct urb *urb)
{
int rc = 0;
- spin_lock(&hcd_urb_list_lock);
+ spin_lock(&hcd->hcd_urb_list_lock);
/* Check that the URB isn't being killed */
if (unlikely(urb->reject)) {
@@ -1033,7 +1030,7 @@ int usb_hcd_link_urb_to_ep(struct usb_hcd *hcd,
struct urb *urb)
goto done;
}
done:
- spin_unlock(&hcd_urb_list_lock);
+ spin_unlock(&hcd->hcd_urb_list_lock);
return rc;
}
EXPORT_SYMBOL_GPL(usb_hcd_link_urb_to_ep);
@@ -1106,9 +1103,9 @@ EXPORT_SYMBOL_GPL(usb_hcd_check_unlink_urb);
void usb_hcd_unlink_urb_from_ep(struct usb_hcd *hcd, struct urb *urb)
{
/* clear all state linking urb to this dev (and hcd) */
- spin_lock(&hcd_urb_list_lock);
+ spin_lock(&hcd->hcd_urb_list_lock);
list_del_init(&urb->urb_list);
- spin_unlock(&hcd_urb_list_lock);
+ spin_unlock(&hcd->hcd_urb_list_lock);
}
EXPORT_SYMBOL_GPL(usb_hcd_unlink_urb_from_ep);
@@ -1311,7 +1308,7 @@ void usb_hcd_flush_endpoint(struct usb_device
*udev,
hcd = bus_to_hcd(udev->bus);
/* No more submits can occur */
- spin_lock_irq(&hcd_urb_list_lock);
+ spin_lock_irq(&hcd->hcd_urb_list_lock);
rescan:
list_for_each_entry (urb, &ep->urb_list, urb_list) {
int is_in;
@@ -1320,7 +1317,7 @@ rescan:
continue;
usb_get_urb (urb);
is_in = usb_urb_dir_in(urb);
- spin_unlock(&hcd_urb_list_lock);
+ spin_unlock(&hcd->hcd_urb_list_lock);
/* kick hcd */
unlink1(hcd, urb, -ESHUTDOWN);
@@ -1345,14 +1342,14 @@ rescan:
usb_put_urb (urb);
/* list contents may have changed */
- spin_lock(&hcd_urb_list_lock);
+ spin_lock(&hcd->hcd_urb_list_lock);
goto rescan;
}
- spin_unlock_irq(&hcd_urb_list_lock);
+ spin_unlock_irq(&hcd->hcd_urb_list_lock);
/* Wait until the endpoint queue is completely empty */
while (!list_empty (&ep->urb_list)) {
- spin_lock_irq(&hcd_urb_list_lock);
+ spin_lock_irq(&hcd->hcd_urb_list_lock);
/* The list may have changed while we acquired the spinlock */
urb = NULL;
@@ -1361,7 +1358,7 @@ rescan:
urb_list);
usb_get_urb (urb);
}
- spin_unlock_irq(&hcd_urb_list_lock);
+ spin_unlock_irq(&hcd->hcd_urb_list_lock);
if (urb) {
usb_kill_urb (urb);
@@ -1618,6 +1615,7 @@ struct usb_hcd *usb_create_hcd (const struct
hc_driver *driver,
dev_dbg (dev, "hcd alloc failed\n");
return NULL;
}
+ spin_lock_init(&hcd->hcd_urb_list_lock);
dev_set_drvdata(dev, hcd);
kref_init(&hcd->kref);
diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h
index 98e2419..e23ff45 100644
--- a/drivers/usb/core/hcd.h
+++ b/drivers/usb/core/hcd.h
@@ -128,6 +128,7 @@ struct usb_hcd {
* input size of periodic table to an interrupt scheduler.
* (ohci 32, uhci 1024, ehci 256/512/1024).
*/
+ spinlock_t hcd_urb_list_lock;
/* The HC driver's private data is stored at the end of
* this structure.
--
1.4.4.2
--
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