[patch] fix driver_register() return value

[patch] fix driver_register() return value

[Stas Sergeev]

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Hi Greg.

In this patch:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=16dc42e018c2868211b4928f20a957c0c216126c
the check was added for another
driver to already claim the same
device on the same bus. But the
returned error code was wrong:
to modprobe, the -EEXIST means
that _this_ driver is already
installed. It therefore doesn't
produce the needed error message
when _another_ driver is trying
to register for the same device.
Returning -EBUSY fixes the problem.

Signed-off-by: Stas Sergeev <stsp@aknet.ru>

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diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index ed2ebd3..f367885 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -236,7 +236,7 @@ int driver_register(struct device_driver *drv)
 		put_driver(other);
 		printk(KERN_ERR "Error: Driver '%s' is already registered, "
 			"aborting...\n", drv->name);
-		return -EEXIST;
+		return -EBUSY;
 	}
 
 	ret = bus_add_driver(drv);

Re: [patch] fix driver_register() return value

[Greg KH]

On Sun, Oct 18, 2009 at 12:31:38AM +0400, Stas Sergeev wrote:
> Hi Greg.
>
> In this patch:
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=16dc42e018c2868211b4928f20a957c0c216126c
> the check was added for another
> driver to already claim the same
> device on the same bus. But the
> returned error code was wrong:
> to modprobe, the -EEXIST means
> that _this_ driver is already
> installed. It therefore doesn't
> produce the needed error message
> when _another_ driver is trying
> to register for the same device.
> Returning -EBUSY fixes the problem.
>
> Signed-off-by: Stas Sergeev <stsp@aknet.ru>

Does this cause problems with the way things now are?  If so, what are
they?  Does this change need to be backported to older -stable kernels?

thanks,

greg k-h

Re: [patch] fix driver_register() return value

[Stas Sergeev]

18.10.2009 00:46, Greg KH wrote:
>> Returning -EBUSY fixes the problem.
>> Signed-off-by: Stas Sergeev<stsp@aknet.ru>
> Does this cause problems with the way things now are?  If so, what are
> they?
They are simple.
Suppose the pcspkr driver was loaded
by the udev. Then someone types:
modprobe snd-pcsp
and that doesn't print anything, so
he thinks the snd-pcsp was loaded and
asks me why there is no sound. :)
Only by typing "dmesg" you can see what
actually happened, but it would be better
to have that from modprobe too.

> Does this change need to be backported to older -stable kernels?
I think it can't hurt.

patch driver-core-fix-driver_register-return-value.patch added to gregkh-2.6 tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Subject: Driver core: fix driver_register() return value

to my gregkh-2.6 tree.  Its filename is

    driver-core-fix-driver_register-return-value.patch

This tree can be found at 
    http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/


>From stsp@aknet.ru  Mon Oct 26 16:00:03 2009
From: Stas Sergeev <stsp@aknet.ru>
Date: Sun, 18 Oct 2009 00:31:38 +0400
Subject: Driver core: fix driver_register() return value
To: Greg KH <gregkh@suse.de>
Cc: Linux kernel <linux-kernel@vger.kernel.org>
Message-ID: <4ADA29AA.9070907@aknet.ru>

In this patch:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=16dc42e018c2868211b4928f20a957c0c216126c
the check was added for another driver to already claim the same device
on the same bus. But the returned error code was wrong: to modprobe, the
-EEXIST means that _this_ driver is already installed. It therefore
doesn't produce the needed error message when _another_ driver is trying
to register for the same device.  Returning -EBUSY fixes the problem.

Signed-off-by: Stas Sergeev <stsp@aknet.ru>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/base/driver.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -236,7 +236,7 @@ int driver_register(struct device_driver
 		put_driver(other);
 		printk(KERN_ERR "Error: Driver '%s' is already registered, "
 			"aborting...\n", drv->name);
-		return -EEXIST;
+		return -EBUSY;
 	}
 
 	ret = bus_add_driver(drv);