On Tue, Apr 12, 2011 at 12:12:47AM +0200, RafaÅ MiÅecki wrote: > 2011/4/11 Greg KH <greg@xxxxxxxxx>: > > On Mon, Apr 11, 2011 at 11:36:39PM +0200, RafaÅ MiÅecki wrote: > >> 2011/4/11 Greg KH <greg@xxxxxxxxx>: > >> > Please read the documentation for how to do this properly. ÂI find it > >> > really hard to believe that you wrote that comment instead of putting in > >> > the 2 lines of code required for this function. > >> > > >> > Especially as-it-is, your code does not work properly and leaks memory > >> > badly. ÂWhy would you do that on purpose? > >> > >> I tried to read some documentation about this. > >> > >> 1) driver-mode/device.txt says only that: > >> > Callback to free the device after all references have > >> > gone away. This should be set by the allocator of the > >> > device (i.e. the bus driver that discovered the device). > >> I *really* do not know how my driver should "free" core on AXI bus. > > > > The structure that you have created, added to the bus, is now ready to > > have its memory freed. ÂSo free it. > > > > This usually means something like: > > Â Â Â Âstruct my_obj = to_my_obj(dev); > > Â Â Â Âkfree(my_obj); > > in the release function. > > I register core->dev to the bus (I set core->dev.bus and > core->dev.parent, is that what you mean?). This core->dev is "struct > dev" embedded in "struct axi_device". By embedded I mean it is *not* a > pointer, I do not alloc it, it's part of the "struct axi_device". That is exactly as it should be. Then in your release function, free the struct axi_device. It's that simple. To try to free it before then would be wrong and cause problems. > >> 2) LDD3 says: > >> > The method is called when the last reference to the device is removed; it is called > >> > from the embedded kobjectâs release method. All device structures registered with > >> > the core must have a release method, or the kernel prints out scary complaints. > >> Well, I do not register any structs for AXI core. > > > > Yes you did, otherwise you would have never seen that callback warning > > you that you needed a release function. > > I was thinking about alloc, sorry, ignore this one. > > > >> 4) SSB in it's ssb_release_dev just calls kfree on struct that was > >> allocated when registering drivers. *I do not* allocate such a struct, > >> so I believe I do exactly the same memory leak as SSB does. > > > > Well someone allocated it, right? ÂWho did it? ÂIf it wasn't you, where > > did that structure come from and why are you registering it on your bus? > > > >> Can you spend 2 more minues in addition to commenting my ideas and > >> help me with writing that 2 lines I missed? Where do I leak memory in > >> my driver? Which struct should I kfree? > > > > The structure that you wrap around 'struct device' for your bus. > > As explained above, this I do not dynamically alloc this 'struct > device'. So is there really any memory leak? Yes, no one ever freed your struct axi_device that you created. thanks, greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
