Hi Peter
Thanks for your reply. Unfortunately we cannot reproduce the issue on a newer kernel as it requires userspace applications (for processing the hotswap) that rely on our (many) changes to the kernel. I appreciate you taking the time to consider the issue.
Thanks
David
________________________________________
From: Peter Rosin <peda@xxxxxxxxxx>
Sent: Tuesday, 20 June 2017 7:30 a.m.
To: Wolfram Sang; David Thomson
Cc: linux-i2c@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] i2c: core: Prevent race condition when removing i2c devices
On 2017-06-19 18:34, Peter Rosin wrote:
> It would certainly be nice to know why .owner is clobbered, because I
> don't see it. But then again, I don't know what sources I should be
> reading...
BTW, one thing I noticed when reading the current code is that I see this
at the end of i2c_del_adapter:
/* Clear the device structure in case this adapter is ever going to be
added again */
memset(&adap->dev, 0, sizeof(adap->dev));
}
EXPORT_SYMBOL(i2c_del_adapter);
which is not very compatible with this part of the device_add() docs:
* Do not call this routine or device_register() more than once for
* any device structure. The driver model core is not designed to work
* with devices that get unregistered and then spring back to life.
* (Among other things, it's very hard to guarantee that all references
* to the previous incarnation of @dev have been dropped.) Allocate
* and register a fresh new struct device instead.
That, of course, probably have no bearing on the problem/patch in this
thread...
Or maybe struct device reuse is exactly what is going on???
Cheers,
peda
