linux-kernel - Re: [PATCH v3 16/22] ACPI: platform_profile: Set profile for all registered handlers

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Message-ID: <0fd4c5ec-3645-300e-baee-cb6468039f75@linux.intel.com>
Date: Thu, 31 Oct 2024 16:37:26 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Mario Limonciello <mario.limonciello@....com>
cc: Hans de Goede <hdegoede@...hat.com>, 
    "Rafael J . Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
    Maximilian Luz <luzmaximilian@...il.com>, Lee Chun-Yi <jlee@...e.com>, 
    Shyam Sundar S K <Shyam-sundar.S-k@....com>, 
    Corentin Chary <corentin.chary@...il.com>, 
    "Luke D . Jones" <luke@...nes.dev>, Ike Panhc <ike.pan@...onical.com>, 
    Henrique de Moraes Holschuh <hmh@....eng.br>, 
    Alexis Belmonte <alexbelm48@...il.com>, 
    Uwe Kleine-König <u.kleine-koenig@...gutronix.de>, 
    Ai Chao <aichao@...inos.cn>, Gergo Koteles <soyer@....hu>, 
    open list <linux-kernel@...r.kernel.org>, 
    "open list:ACPI" <linux-acpi@...r.kernel.org>, 
    "open list:MICROSOFT SURFACE PLATFORM PROFILE DRIVER" <platform-driver-x86@...r.kernel.org>, 
    "open list:THINKPAD ACPI EXTRAS DRIVER" <ibm-acpi-devel@...ts.sourceforge.net>, 
    Mark Pearson <mpearson-lenovo@...ebb.ca>, 
    Matthew Schwartz <matthew.schwartz@...ux.dev>
Subject: Re: [PATCH v3 16/22] ACPI: platform_profile: Set profile for all
 registered handlers

On Thu, 31 Oct 2024, Mario Limonciello wrote:

> On 10/31/2024 05:25, Ilpo Järvinen wrote:
> > On Wed, 30 Oct 2024, Mario Limonciello wrote:
> > 
> > > If multiple platform profile handlers have been registered then when
> > > setting a profile verify that all profile handlers support the requested
> > > profile and set it to each handler.
> > > 
> > > If this fails for any given handler, revert all profile handlers back to
> > > balanced and log an error into the kernel ring buffer.
> > > 
> > > Tested-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
> > > Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> > > ---
> > >   drivers/acpi/platform_profile.c | 25 ++++++++++++++++++++-----
> > >   1 file changed, 20 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/acpi/platform_profile.c
> > > b/drivers/acpi/platform_profile.c
> > > index 90cbc0de4d5bc..c2bb325ba531c 100644
> > > --- a/drivers/acpi/platform_profile.c
> > > +++ b/drivers/acpi/platform_profile.c
> > > @@ -99,6 +99,8 @@ static ssize_t platform_profile_store(struct device
> > > *dev,
> > >   			    struct device_attribute *attr,
> > >   			    const char *buf, size_t count)
> > >   {
> > > +	struct platform_profile_handler *handler;
> > > +	unsigned long choices;
> > >   	int err, i;
> > >     	/* Scan for a matching profile */
> > > @@ -107,16 +109,29 @@ static ssize_t platform_profile_store(struct device
> > > *dev,
> > >   		return -EINVAL;
> > >     	scoped_cond_guard(mutex_intr, return -ERESTARTSYS,
> > > &profile_lock) {
> > > -		if (!cur_profile)
> > > +		if (!platform_profile_is_registered())
> > >   			return -ENODEV;
> > >   -		/* Check that platform supports this profile choice */
> > > -		if (!test_bit(i, cur_profile->choices))
> > > +		/* Check that all handlers support this profile choice */
> > > +		choices = platform_profile_get_choices();
> > > +		if (!test_bit(i, &choices))
> > >   			return -EOPNOTSUPP;
> > >   -		err = cur_profile->profile_set(cur_profile, i);
> > > -		if (err)
> > > +		list_for_each_entry(handler, &platform_profile_handler_list,
> > > list) {
> > > +			err = handler->profile_set(handler, i);
> > > +			if (err) {
> > > +				pr_err("Failed to set profile for handler
> > > %s\n", handler->name);
> > > +				break;
> > > +			}
> > > +		}
> > > +		if (err) {
> > > +			list_for_each_entry_continue_reverse(handler,
> > > &platform_profile_handler_list, list) {
> > 
> > Too long line.
> > 
> > This looks an error rollback though so instead of break inside the loop
> > you could goto into a label at the end of the function and have much less
> > indentation to begin with.
> 
> How does the scoped_cond_guard interact with a goto?  With the jump I had
> guessed it goes out of scope, but I wasn't really sure what the compiler does.
> 
> I guess in the goto label I'll need another scoped_cond_guard()?

Ah, the scope problem is a good point.

Perhaps you could instead add e.g. platform_profile_reset_default() and 
call that before break, both patches that had the rollback did the same 
thing anyway so it can be reused too.

-- 
 i.