On Tue, May 28, 2019 at 11:39:22AM +0000, Kalle Valo wrote:
> Gen Zhang <[email protected]> wrote:
>
> > In wl1271_probe(), 'glue->core' is allocated by platform_device_alloc(),
> > when this allocation fails, ENOMEM is returned. However, 'pdev_data'
> > and 'glue' are allocated by devm_kzalloc() before 'glue->core'. When
> > platform_device_alloc() returns NULL, we should also free 'pdev_data'
> > and 'glue' before wl1271_probe() ends to prevent leaking memory.
> >
> > Similarly, we shoulf free 'pdev_data' when 'glue' is NULL. And we should
> > free 'pdev_data' and 'glue' when 'glue->reg' is error and when 'ret' is
> > error.
> >
> > Further, we should free 'glue->core', 'pdev_data' and 'glue' when this
> > function normally ends to prevent leaking memory.
> >
> > Signed-off-by: Gen Zhang <[email protected]>
>
> Same questions as with similar SDIO patch:
>
> https://patchwork.kernel.org/patch/10959049/
>
> Patch set to Changes Requested.
>
> --
> https://patchwork.kernel.org/patch/10959053/
>
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
>
Thanks for your reply, Kalle. I had debate with Jon about this patch.
You could kindly refer to lkml: https://lkml.org/lkml/2019/5/23/1547.
And I don't think a practical conclusion is made there.
Further, I e-mailed Greg K-H about when should we use devm_kmalloc().
On Tue, May 28, 2019 at 08:32:57AM +0800, Gen Zhang wrote:
> devm_kmalloc() is used to allocate memory for a driver dev. Comments
> above the definition and doc
> (https://www.kernel.org/doc/Documentation/driver-model/devres.txt) all
> imply that allocated the memory is automatically freed on driver attach,
> no matter allocation fail or not. However, I examined the code, and
> there are many sites that devm_kfree() is used to free devm_kmalloc().
> e.g. hisi_sas_debugfs_init() in drivers/scsi/hisi_sas/hisi_sas_main.c.
> So I am totally confused about this issue. Can anybody give me some
> guidance? When should we use devm_kfree()?
He replied: If you "know" you need to free the memory now,
call devm_kfree(). If you want to wait for it to be cleaned up latter,
like normal, then do not call it.
So could please look in to this issue?
Thanks
Gen