[PATCH 3/3] dm: core: Default to using DEVRES outside of xPL

[Michael Nazzareno Trimarchi]

Hi

On Fri, Dec 26, 2025 at 7:57 PM Tom Rini <trini at konsulko.com> wrote:
>
> On Fri, Dec 26, 2025 at 07:28:43PM +0100, Michael Nazzareno Trimarchi wrote:
> > Hi Tom
> >
> > On Fri, Dec 19, 2025 at 9:21 PM Tom Rini <trini at konsulko.com> wrote:
> > >
> > > The devm alloc functions that we have may follow the Linux kernel model
> > > where allocations are (almost always) automatically free()'d. However,
> > > quite often we don't enable, in full U-Boot, the corresponding automatic
> > > free. This in turn leads to memory leaks. Rather than manually tracking
> > > allocations and implementing frees, rework things so that we follow
> > > expectations now and enable the DEVRES functionality to manage frees.
> > >
> > > This turns DEVRES from a prompted symbol to a symbol that must be
> > > select'd, and we now remove our non-managed alloc/free functions from
> > > outside of xPL builds.
> [snip]
> > > @@ -279,8 +280,8 @@ config DEVRES
> > >           released whether initialization fails half-way or the device gets
> > >           detached.
> > >
> > > -         If this option is disabled, devres functions fall back to
> > > -         non-managed variants.  For example, devres_alloc() to kzalloc(),
> > > +         This option is disabled in xPL phases anddevres functions fall back
> >
> > Fix this typo
>
> OK.
>
> [snip]
> > Can you please in the commit message a concrete example on what this
> > commit takes care of?
> > In short expand here:
> > " in full U-Boot, the corresponding automatic free. This in turn leads
> > to memory leaks."
>
> Sure. So for example:
> commit 00e1fed93c8c3e4c9037741ea1b70a9e693a6e65
> Author: Francois Berder <fberder at outlook.fr>
> Date:   Tue Nov 11 11:30:19 2025 +0100
>
>     firmware: ti_sci: Fix memory leaks in devm_ti_sci_get_of_resource
>
>     - Fix temp memory leak
>     - Free memory during error handling
>
>     Signed-off-by: Francois Berder <fberder at outlook.fr>
>
> Is needed (I'd have to re-read the threads to see if in whole or in
> part) because DEVRES is optional today. And barring
> drivers/core/devres.c doesn't work the way it's documented and expected,
> the normal unwind path will eventually say "Ah, and devm_kfree these
> devm_kmalloc'd areas". This was part of either the discussion for that
> patch, or another one of Francois' patches adding devm_kfree() calls to
> devm_kmalloc()'d areas.

As far as I understand the devres_release_probe should then free the resources
allocated to dm_device.

Michael

>
> --
> Tom



-- 
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael at amarulasolutions.com
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