From: Ming Lei <[email protected]>
This patch moves bus->match out from driver_probe_device and
does not hold device lock to check the match between a device
and a driver.
The idea has been verified by the commit 6cd495860901,
which leads to a faster boot. But the commit 6cd495860901 has
the following drawbacks: 1),only does the quick check in
the path of __driver_attach->driver_probe_device, not in other
paths; 2),for a matched device and driver, check the same match
twice. It is a waste of cpu ,especially for some drivers with long
device id table (eg. usb-storage driver).
This patch adds a helper of driver_match_device to check the match
in all paths, and testes the match only once.
Signed-off-by: Ming Lei <[email protected]>
---
drivers/base/base.h | 5 +++++
drivers/base/bus.c | 2 +-
drivers/base/dd.c | 19 +++++++------------
3 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/base/base.h b/drivers/base/base.h
index 0a5f055..e2599ba 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -86,6 +86,11 @@ extern void bus_remove_driver(struct device_driver *drv);
extern void driver_detach(struct device_driver *drv);
extern int driver_probe_device(struct device_driver *drv, struct device *dev);
+static inline int driver_match_device(struct device_driver *drv,
+ struct device *dev)
+{
+ return drv->bus->match && drv->bus->match(dev, drv);
+}
extern void sysdev_shutdown(void);
extern int sysdev_suspend(pm_message_t state);
diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 83f32b8..8547b78 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -198,7 +198,7 @@ static ssize_t driver_bind(struct device_driver *drv,
int err = -ENODEV;
dev = bus_find_device_by_name(bus, NULL, buf);
- if (dev && dev->driver == NULL) {
+ if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
if (dev->parent) /* Needed for USB */
down(&dev->parent->sem);
down(&dev->sem);
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 315bed8..9b721d3 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -172,14 +172,8 @@ int driver_probe_done(void)
* @drv: driver to bind a device to
* @dev: device to try to bind to the driver
*
- * First, we call the bus's match function, if one present, which should
- * compare the device IDs the driver supports with the device IDs of the
- * device. Note we don't do this ourselves because we don't know the
- * format of the ID structures, nor what is to be considered a match and
- * what is not.
- *
- * This function returns 1 if a match is found, -ENODEV if the device is
- * not registered, and 0 otherwise.
+ * This function returns -ENODEV if the device is not registered,
+ * 1 if the device is bound sucessfully and 0 otherwise.
*
* This function must be called with @dev->sem held. When called for a
* USB interface, @dev->parent->sem must be held as well.
@@ -190,21 +184,22 @@ int driver_probe_device(struct device_driver *drv, struct device *dev)
if (!device_is_registered(dev))
return -ENODEV;
- if (drv->bus->match && !drv->bus->match(dev, drv))
- goto done;
pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);
ret = really_probe(dev, drv);
-done:
return ret;
}
static int __device_attach(struct device_driver *drv, void *data)
{
struct device *dev = data;
+
+ if (!driver_match_device(drv, dev))
+ return 0;
+
return driver_probe_device(drv, dev);
}
@@ -257,7 +252,7 @@ static int __driver_attach(struct device *dev, void *data)
* is an error.
*/
- if (drv->bus->match && !drv->bus->match(dev, drv))
+ if (!driver_match_device(drv, dev))
return 0;
if (dev->parent) /* Needed for USB */
--
1.6.0
On Wed, 21 Jan 2009 23:27:47 +0800,
[email protected] wrote:
> From: Ming Lei <[email protected]>
>
> This patch moves bus->match out from driver_probe_device and
> does not hold device lock to check the match between a device
> and a driver.
>
> The idea has been verified by the commit 6cd495860901,
> which leads to a faster boot. But the commit 6cd495860901 has
> the following drawbacks: 1),only does the quick check in
> the path of __driver_attach->driver_probe_device, not in other
> paths; 2),for a matched device and driver, check the same match
> twice. It is a waste of cpu ,especially for some drivers with long
> device id table (eg. usb-storage driver).
>
> This patch adds a helper of driver_match_device to check the match
> in all paths, and testes the match only once.
>
> Signed-off-by: Ming Lei <[email protected]>
> ---
> drivers/base/base.h | 5 +++++
> drivers/base/bus.c | 2 +-
> drivers/base/dd.c | 19 +++++++------------
> 3 files changed, 13 insertions(+), 13 deletions(-)
The patch looks fine to me, and it seems to work well on my s390 LPAR.
Acked-by: Cornelia Huck <[email protected]>
[email protected] writes:
> +static inline int driver_match_device(struct device_driver *drv,
> + struct device *dev)
> +{
> + return drv->bus->match && drv->bus->match(dev, drv);
> +}
This logic is wrong. !(a && !b) <=> !a || b, not a && b
A bus that does not have a match function now never matches, whereas
previously it would always match. This breaks aoa-soundbus.
Andreas.
---
driver core: Fix logic in driver_match_device
A bus that does not have a match function always matches. This fixes
49b420a13ff9 ("driver core: check bus->match without holding device
lock").
Signed-off-by: Andreas Schwab <[email protected]>
---
drivers/base/base.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/base/base.h b/drivers/base/base.h
index ddc9749..087e911 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -115,7 +115,7 @@ extern int driver_probe_device(struct device_driver *drv, struct device *dev);
static inline int driver_match_device(struct device_driver *drv,
struct device *dev)
{
- return drv->bus->match && drv->bus->match(dev, drv);
+ return !drv->bus->match || drv->bus->match(dev, drv);
}
extern void sysdev_shutdown(void);
--
Andreas Schwab, [email protected]
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
2009/4/10 Andreas Schwab <[email protected]>:
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index ddc9749..087e911 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -115,7 +115,7 @@ extern int driver_probe_device(struct device_driver *drv, struct device *dev);
> ?static inline int driver_match_device(struct device_driver *drv,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct device *dev)
> ?{
> - ? ? ? return drv->bus->match && drv->bus->match(dev, drv);
> + ? ? ? return !drv->bus->match || drv->bus->match(dev, drv);
> ?}
A similar patch has been in greg's tree:
http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/driver-core.current/driver-core-fix-driver_match_device.patch
Thanks!
--
Lei Ming