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Date:   Wed, 16 Dec 2020 11:23:21 +0800
From:   Chen-Yu Tsai <wens@...nel.org>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        netdev <netdev@...r.kernel.org>, kernel-janitors@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: allwinner: Fix some resources leak in the error
 handling path of the probe and in the remove function

On Wed, Dec 16, 2020 at 4:16 AM Christophe JAILLET
<christophe.jaillet@...adoo.fr> wrote:
>
> Le 15/12/2020 à 20:35, Dan Carpenter a écrit :
> > On Tue, Dec 15, 2020 at 08:08:15PM +0100, Maxime Ripard wrote:
> >> On Tue, Dec 15, 2020 at 07:18:48PM +0100, Christophe JAILLET wrote:
> >>> Le 15/12/2020 à 12:37, Maxime Ripard a écrit :
> >>>> On Tue, Dec 15, 2020 at 12:11:53PM +0300, Dan Carpenter wrote:
> >>>>> On Tue, Dec 15, 2020 at 09:56:55AM +0100, Maxime Ripard wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> On Mon, Dec 14, 2020 at 09:21:17PM +0100, Christophe JAILLET wrote:
> >>>>>>> 'irq_of_parse_and_map()' should be balanced by a corresponding
> >>>>>>> 'irq_dispose_mapping()' call. Otherwise, there is some resources leaks.
> >>>>>>
> >>>>>> Do you have a source to back that? It's not clear at all from the
> >>>>>> documentation for those functions, and couldn't find any user calling it
> >>>>>> from the ten-or-so random picks I took.
> >>>>>
> >>>>> It looks like irq_create_of_mapping() needs to be freed with
> >>>>> irq_dispose_mapping() so this is correct.
> >>>>
> >>>> The doc should be updated first to make that clear then, otherwise we're
> >>>> going to fix one user while multiples will have poped up
> >>>>
> >>>> Maxime
> >>>>
> >>>
> >>> Hi,
> >>>
> >>> as Dan explained, I think that 'irq_dispose_mapping()' is needed because of
> >>> the 'irq_create_of_mapping()" within 'irq_of_parse_and_map()'.
> >>>
> >>> As you suggest, I'll propose a doc update to make it clear and more future
> >>> proof.
> >>
> >> Thanks :)
> >>
> >> And if you feel like it, a coccinelle script would be awesome too so
> >> that other users get fixed over time
> >>
> >> Maxime
> >
> > Smatch has a new check for resource leaks which hopefully people will
> > find useful.
> >
> > https://github.com/error27/smatch/blob/master/check_unwind.c
>
> Nice :)
> I wasn't aware of it.
>
> >
> > To check for these I would need to add the following lines to the table:
> >
> >          { "irq_of_parse_and_map", ALLOC, -1, "$", &int_one, &int_max},
> >          { "irq_create_of_mapping", ALLOC, -1, "$", &int_one, &int_max},
> >          { "irq_dispose_mapping", RELEASE, 0, "$"},
> >
> > The '-1, "$"' means the returned value.  irq_of_parse_and_map() and
> > irq_create_of_mapping() return positive int on success.
> >
> > The irq_dispose_mapping() frees its zeroth parameter so it's listed as
> > '0, "$"'.  We don't care about the returns from irq_dispose_mapping().
> >
> > It doesn't apply in this case but if a function frees a struct member
> > then that's listed as '0, "$->member_name"'.
> >
> > regards,
> > dan carpenter
> >
>
> The script I use to try to spot missing release function is:
> ///
> @@
> expression  x, y;
> identifier f, l;
> @@
>
> *       x = irq_of_parse_and_map(...);
>          ... when any
> *       y = f(...);
>          ... when any
> *       if (<+... y ...+>)
>          {
>                  ...
> (
> *               goto l;
> |
> *               return ...;
> )
>                  ...
>          }
>          ... when any
> *l:
>          ... when != irq_dispose_mapping(...);
> *       return ...;
> ///
>
> It is likely that some improvement can be made, but it works pretty well
> for what I want.
>
> And I have a collection of alloc/free functions that I manually put in
> place of irq_of_parse_and_map and irq_dispose_mapping.

AFAICT the resource leak is likely larger in scope, as many drivers use
platform_get_irq(), which eventually ends up calling irq_create_of_mapping()
through of_irq_get() in the OF path. Same goes for platform_get_irq_byname().

ChenYu


> Up to know, this list is:
>
> // alloc_etherdev/alloc_etherdev_mq/alloc_etherdev_mqs - free_netdev
> // alloc_workqueue - destroy_workqueue
> // class_register - class_unregister
> // clk_get - clk_put
> // clk_prepare - clk_unprepare
> // create_workqueue - destroy_workqueue
> // create_singlethread_workqueue - destroy_workqueue
> //
> dev_pm_domain_attach/dev_pm_domain_attach_by_id/dev_pm_domain_attach_by_name
> - dev_pm_domain_detach
> // devres_alloc - devres_free
> // dma_alloc_coherent - dma_free_coherent
> // dma_map_resource - dma_unmap_resource
> // dma_map_single - dma_unmap_single
> // dma_request_slave_channel - dma_release_channel
> // dma_request_chan - dma_release_channel
> // framebuffer_alloc - framebuffer_release
> // get_device - put_device
> // iio_channel_get - iio_channel_release
> // ioremap - iounmap
> // input_allocate_device - input_free_device
> // input_register_handle - input_unregister_handle
> // irq_of_parse_and_map / irq_create_of_mapping - irq_dispose_mapping
> // kmalloc - kfree
> // mempool_alloc - mempool_free
> // of_node_get - of_node_put
> // of_reserved_mem_device_init - of_reserved_mem_device_release
> // pinctrl_register - pinctrl_unregister
> // request_irq - free_irq
> // request_region - release_region
> // request_mem_region - release_mem_region
> // reset_control_assert - reset_control_deassert
> // scsi_host_alloc - scsi_host_put
>
> // pci_alloc_irq_vectors - pci_free_irq_vectors
> // pci_dev_get - pci_dev_put
> // pci_enable_device - pci_disable_device
> // pci_iomap - pci_iounmap
> // pci_request_region - pci_release_region
> // pci_request_regions - pci_release_regions
>
> // alloc_skb/__alloc_skb - kfree_skb/__kfree_skb
> // dev_alloc_skb - dev_kfree_skb
>
> // spi_dev_get - spi_dev_put
> // spi_message_alloc - spi_message_free
> // spi_register_master - spi_unregister_master
>
>
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