From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from kroah.org ([198.145.64.141]:38957 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755910Ab1DKWmJ (ORCPT ); Mon, 11 Apr 2011 18:42:09 -0400 Date: Mon, 11 Apr 2011 15:36:32 -0700 From: Greg KH To: =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: linux-wireless@vger.kernel.org, "John W. Linville" , George Kashperko , Arnd Bergmann , Russell King , "linux-kernel@vger.kernel.org" , b43-dev@lists.infradead.org, Michael =?iso-8859-1?Q?B=FCsch?= , linuxdriverproject , Andy Botting , "linux-arm-kernel@lists.infradead.org" , Larry Finger Subject: Re: [RFC][PATCH V3] axi: add AXI bus driver Message-ID: <20110411223632.GB31833@kroah.com> References: <1302557114-7880-1-git-send-email-zajec5@gmail.com> <20110411210631.GA28559@kroah.com> <20110411212513.GA17809@kroah.com> <20110411215619.GA27943@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 In-Reply-To: Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, Apr 12, 2011 at 12:12:47AM +0200, Rafał Miłecki wrote: > 2011/4/11 Greg KH : > > On Mon, Apr 11, 2011 at 11:36:39PM +0200, Rafał Miłecki wrote: > >> 2011/4/11 Greg KH : > >> > 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". 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 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? Yes, no one ever freed your struct axi_device that you created. thanks, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 From: greg@kroah.com (Greg KH) Date: Mon, 11 Apr 2011 15:36:32 -0700 Subject: [RFC][PATCH V3] axi: add AXI bus driver In-Reply-To: References: <1302557114-7880-1-git-send-email-zajec5@gmail.com> <20110411210631.GA28559@kroah.com> <20110411212513.GA17809@kroah.com> <20110411215619.GA27943@kroah.com> Message-ID: <20110411223632.GB31833@kroah.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Apr 12, 2011 at 12:12:47AM +0200, Rafa? Mi?ecki wrote: > 2011/4/11 Greg KH : > > On Mon, Apr 11, 2011 at 11:36:39PM +0200, Rafa? Mi?ecki wrote: > >> 2011/4/11 Greg KH : > >> > 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". 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 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? Yes, no one ever freed your struct axi_device that you created. thanks, greg k-h