On Fri, Nov 20, 2020 at 02:00:55PM +0300, Dan Carpenter wrote: > On Fri, Nov 20, 2020 at 10:39:45AM +0100, Daniel Vetter wrote: > > On Fri, Nov 20, 2020 at 8:58 AM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > > > > > On Thu, Nov 19, 2020 at 08:30:59PM +0100, Daniel Vetter wrote: > > > > On Thu, Nov 19, 2020 at 6:51 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote: > > > > > > > > > > On Thu, Nov 19, 2020 at 12:35:56PM +0100, Hans de Goede wrote: > > > > > > Hi, > > > > > > > > > > > > On 10/27/20 2:51 PM, Hans de Goede wrote: > > > > > > > Add missing pci_iounmap() calls to properly unmap the memory on > > > > > > > probe-failure and remove. > > > > > > > > > > > > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > > > > > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > > > > > > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > > > > > > > > > > > > For some reason the spam-filter used by Red Hat's email system has eaten > > > > > > Daniel Vetter's reply to this, so let me copy and paste that from patchwork: > > > > > > > > > > > > Daniel Vetter wrote: > > > > > > > > > > > > > I think switching over to devm would be really nice. And for pci all > > > > > > > you need to do is use pcim_enable_device and delete all the cleanup > > > > > > > code, and it's all done. Hand rolling device cleanup code really isn't > > > > > > > a great idea and way too error-prone. Plus you're using lots of devm_ > > > > > > > already. > > > > > > > > > > > > Good point, so I just checked and the vboxvideo code is already > > > > > > using pcim_enable_device() so it looks like this is a false-positive > > > > > > from the lkp@xxxxxxxxx bot, and Dan Carpenter missed that pcim_enable_device() > > > > > > makes all subsequent pci-resource acquiring calls behave like devm calls, > > > > > > when he forwarded the report to me. > > > > > > > > > > > > Tl;DR: there is no bug / leak and this patch can be dropped. > > > > > > > > > > > > Is there a place where I can report a bug against the lkp@xxxxxxxxx bot > > > > > > for this false-positive ? > > > > > > > > > > Ah. Thanks! > > > > > > > > > > This is a Smatch bug. There is a list for that smatch@xxxxxxxxxxxxxxx > > > > > but I already remove the pci_iomap() from the list of functions that > > > > > needs to be unwound based on your report. > > > > > > > > I guess if smatch sees a pci_enable_device but not pcim_enable_device > > > > on the same device as passed to pci_iomap (and a pile of other pci > > > > functions) then it still must be unwound. Could smatch detect that? > > > > There's a lot of pci drivers not using the managed functions, catching > > > > bugs in these would be good. > > > > > > It's a lot of code. There would be two ways to implement this: > > > > > > 1) Somehow store the links to figure out the value of: > > > > > > devres_find(vbox->ddev.pdev.dev)->enabled > > > > > > That's very complicated. I'm sort of working on some of the steps > > > involved but and it's probably a multi year process before it's > > > possible. > > > > > > 2) Create a data base table with driver data, then store if the driver > > > calls pcim_enable_device(). This is still a bit of work, but probably > > > straight forward. Storing driver data would be useful for other things > > > as well. > > > > Hm maybe I totally misunderstand how smatch works, but I thought you > > can track additional invariants and stuff on various pointers. So I > > figured you just track whether pci_enable_device has been called on a > > struct pci_device *dev, and then if anyone calls pci_iomap on the same > > pointer and there's no cleanup, it's a bug. For any other case you > > just can't tell (since absence of pcim_enable_device might just mean > > that smatch doesn't see through the maze). Or is that what you meant > > with approach 2? > > Hm... Your idea is another option #3. It's probably less work. > > I'll take a look at it. btw if you do this, the inverse isn't an issue. I.e. a pcim_enable_device on the same pci_device you see a pci_iounmap. This can happen when a driver maps something just to check a few things, reliazes the feature isn't there, and then drops the mapping. It's only redundant when it's on a direct return path of the driver's pci_driver->probe function, or anything that's only called from pci_driver->remove. So quite tricky to correctly catch all cases. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
