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Date: Tue, 12 Apr 2011 00:12:47 +0200 From: Rafał Miłecki <zajec5@...il.com> To: Greg KH <greg@...ah.com> Cc: linux-wireless@...r.kernel.org, "John W. Linville" <linville@...driver.com>, George Kashperko <george@...u.edu.ua>, Arnd Bergmann <arnd@...db.de>, Russell King <rmk@....linux.org.uk>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, b43-dev@...ts.infradead.org, Michael Büsch <mb@...sch.de>, linuxdriverproject <devel@...uxdriverproject.org>, Andy Botting <andy@...ybotting.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, Larry Finger <Larry.Finger@...inger.net> Subject: Re: [RFC][PATCH V3] axi: add AXI bus driver 2011/4/11 Greg KH <greg@...ah.com>: > On Mon, Apr 11, 2011 at 11:36:39PM +0200, Rafał Miłecki wrote: >> 2011/4/11 Greg KH <greg@...ah.com>: >> > Please read the documentation for how to do this properly. I 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. Why 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. So free it. > > This usually means something like: > struct my_obj = to_my_obj(dev); > kfree(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". >> 2) LDD3 says: >> > The method is called when the last reference to the device is removed; it is called >> > from the embedded kobject’s 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? Who did it? If 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? -- Rafał -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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