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authorArjan van de Ven <arjan@linux.intel.com>2008-09-14 08:32:06 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-16 09:24:50 -0700
commit6cd49586090187a2a145bb6570fb2392f121aa22 (patch)
tree67373f2686b61e6a30f402190bf5ac3ec34a0f13
parent286661b3777897220ecfcd774bccc68a34667f39 (diff)
downloadop-kernel-dev-6cd49586090187a2a145bb6570fb2392f121aa22.zip
op-kernel-dev-6cd49586090187a2a145bb6570fb2392f121aa22.tar.gz
device model: Do a quickcheck for driver binding before doing an expensive check
This patch adds a quick check for the driver<->device match before taking the locks and doin gthe expensive checks. Taking the lock hurts in asynchronous boot context where the device lock gets hit; one of the init functions takes the lock and goes to do an expensive hardware init; the other init functions walk the same PCI list and get stuck on the lock as a result. For the common case, we can know there's no chance whatsoever of a match if the device isn't in the drivers ID table... so this patch does that check as a best-effort-avoid-the-lock approach. Bootcharts for before and after can be seen at http://www.fenrus.org/before.svg http://www.fenrus.org/after.svg Note the long time "agp_ali_init" takes in the first graph; my laptop doesn't even have an ALI chip in it! (the bootgraphs look a bit dissimilar, but that's the point, the first one has a bunch of arbitrary delays in it that cause it to look very different) This reduces my kernel boot time by about 20% Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/base/dd.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 3ac443b..20febc0 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -257,6 +257,9 @@ static int __driver_attach(struct device *dev, void *data)
* is an error.
*/
+ if (drv->bus->match && !drv->bus->match(dev, drv))
+ return 0;
+
if (dev->parent) /* Needed for USB */
down(&dev->parent->sem);
down(&dev->sem);
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