2009-01-30 12:48:54

by Ming Lei

Subject: [PATCH] driver core: remove polling for driver_probe_done(v3)

From: Ming Lei <[email protected]>

This patch adds a function : driver_wait_probe_done,
which waits on condition of probing done to replace
polling for driver_probe_done in fs initialization.

There is no better way to avoid polling for
driver_probe_done _and_ existence of the root device,
so we does not replace the driver_probe_done with
driver_wait_probe_done in such special case.

Removing polling in fs initialization may lead to
a faster boot.

Signed-off-by: Ming Lei <[email protected]>
---
drivers/base/dd.c | 12 ++++++++++++
include/linux/device.h | 1 +
init/do_mounts.c | 4 ++--
init/do_mounts_md.c | 3 +--
4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9b721d3..8f9f6fb 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -168,6 +168,18 @@ int driver_probe_done(void)
}

/**
+ * driver_wait_probe_done
+ * Wait until the probe sequence is finished.
+ *
+ */
+void driver_wait_probe_done(void)
+{
+ pr_debug("%s: probe_count = %d\n", __func__,
+ atomic_read(&probe_count));
+ wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
+}
+
+/**
* driver_probe_device - attempt to bind device & driver together
* @drv: driver to bind a device to
* @dev: device to try to bind to the driver
diff --git a/include/linux/device.h b/include/linux/device.h
index 45e5b19..c53cdbf 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -147,6 +147,7 @@ extern void put_driver(struct device_driver *drv);
extern struct device_driver *driver_find(const char *name,
struct bus_type *bus);
extern int driver_probe_done(void);
+extern void driver_wait_probe_done(void);

/* sysfs interface for exporting driver attributes */

diff --git a/init/do_mounts.c b/init/do_mounts.c
index 708105e..9cb1985 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -371,8 +371,8 @@ void __init prepare_namespace(void)
}

/* wait for the known devices to complete their probing */
- while (driver_probe_done() != 0)
- msleep(100);
+ driver_wait_probe_done();
+
async_synchronize_full();

md_run_setup();
diff --git a/init/do_mounts_md.c b/init/do_mounts_md.c
index ff95e31..63b77f0 100644
--- a/init/do_mounts_md.c
+++ b/init/do_mounts_md.c
@@ -281,8 +281,7 @@ static void __init autodetect_raid(void)
*/
printk(KERN_INFO "md: Waiting for all devices to be available before autodetect\n");
printk(KERN_INFO "md: If you don't use raid, use raid=noautodetect\n");
- while (driver_probe_done() < 0)
- msleep(100);
+ driver_wait_probe_done();
fd = sys_open("/dev/md0", 0, 0);
if (fd >= 0) {
sys_ioctl(fd, RAID_AUTORUN, raid_autopart);
--
1.6.0

2009-01-30 13:31:43

by Cornelia Huck

Subject: Re: [PATCH] driver core: remove polling for driver_probe_done(v3)

On Fri, 30 Jan 2009 20:48:35 +0800,
[email protected] wrote:

> From: Ming Lei <[email protected]>
>
> This patch adds a function : driver_wait_probe_done,
> which waits on condition of probing done to replace
> polling for driver_probe_done in fs initialization.
>
> There is no better way to avoid polling for
> driver_probe_done _and_ existence of the root device,
> so we does not replace the driver_probe_done with
> driver_wait_probe_done in such special case.
>
> Removing polling in fs initialization may lead to
> a faster boot.
>
> Signed-off-by: Ming Lei <[email protected]>
> ---
> drivers/base/dd.c | 12 ++++++++++++
> include/linux/device.h | 1 +
> init/do_mounts.c | 4 ++--
> init/do_mounts_md.c | 3 +--
> 4 files changed, 16 insertions(+), 4 deletions(-)

Looks good and also survived a quick test on my s390 LPAR.

2009-01-30 14:53:25

by Arjan van de Ven

Subject: Re: [PATCH] driver core: remove polling for driver_probe_done(v3)

On Fri, 30 Jan 2009 20:48:35 +0800
[email protected] wrote:

> From: Ming Lei <[email protected]>
>
> This patch adds a function : driver_wait_probe_done,
> which waits on condition of probing done to replace
> polling for driver_probe_done in fs initialization.
>
> There is no better way to avoid polling for
> driver_probe_done _and_ existence of the root device,
> so we does not replace the driver_probe_done with
> driver_wait_probe_done in such special case.
>
> Removing polling in fs initialization may lead to
> a faster boot.
>
> Signed-off-by: Ming Lei <[email protected]>

ok this one will work fine ;)

Reviewed-by: Arjan van de Ven <[email protected]>

thanks for fixing this up
(it will clash with the patch that moves this to one place, but the
same cleanup can be done there)


--
Arjan van de Ven Intel Open Source Technology Centre
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