Re: [PATCH] uio: Fix uio driver to refcount device
From: Brian Russell
Date: Wed Mar 11 2015 - 11:59:54 EST
On 11/03/15 15:43, Greg Kroah-Hartman wrote:
> On Wed, Mar 11, 2015 at 03:31:42PM +0000, Brian Russell wrote:
>> Protect uio driver from crashing if its owner is hot unplugged while there
>> are open fds.
>> Signed-off-by: Brian Russell <brussell@xxxxxxxxxxx>
> Minor nit, you need a blank line before your s-o-b: line.
>> drivers/uio/uio.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
>> index 6276f13..70ce015 100644
>> --- a/drivers/uio/uio.c
>> +++ b/drivers/uio/uio.c
>> @@ -434,9 +434,11 @@ static int uio_open(struct inode *inode, struct file *filep)
>> goto out;
>> + get_device(idev);
> What is the real oops caused when a device is removed? Protecting this
> with a reference count seems ok, but it seems "heavy".
I'm seeing it with PCI hotplug. The PCI subsystem calls remove and the owner module in turn calls uio_unregister_device while app stil has open fds.
> greg k-h
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