linux-kernel - [PATCH] apm-emulation: remove unused __apm_get_power

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Message-ID: <ba3nzxffdpuz2eo5kbpm5iez2rcdves3qpd4kvnmshxwjburwo@tarta.nabijaczleweli.xyz>
Date: Fri, 17 Oct 2025 00:05:10 +0200
From: 
	Ahelenia Ziemiańska <nabijaczleweli@...ijaczleweli.xyz>
To: Jiri Kosina <jikos@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] apm-emulation: remove unused __apm_get_power_status

The API for apm_get_power_status is "call it if it isn't NULL",
except it's also initialised with a no-op __apm_get_power_status.
This was added alongside apm_get_power_status in 2007.

The apm_get_power_status symbol is used in these files:
  arch/arm/mach-pxa/sharpsl_pm.c:extern void (*apm_get_power_status)(struct apm_power_info *);
  arch/arm/mach-pxa/sharpsl_pm.c: apm_get_power_status = sharpsl_apm_get_power_status;
  arch/sh/boards/mach-hp6xx/hp6xx_apm.c:  apm_get_power_status = hp6x0_apm_get_power_status;
  drivers/char/apm-emulation.c:void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
  drivers/char/apm-emulation.c:EXPORT_SYMBOL(apm_get_power_status);
  drivers/char/apm-emulation.c:   if (apm_get_power_status)
  drivers/char/apm-emulation.c:           apm_get_power_status(&info);
  drivers/macintosh/apm_emu.c:    apm_get_power_status = pmu_apm_get_power_status;
  drivers/macintosh/apm_emu.c:    if (apm_get_power_status == pmu_apm_get_power_status)
  drivers/macintosh/apm_emu.c:            apm_get_power_status = NULL;
  drivers/power/supply/apm_power.c:       apm_get_power_status = apm_battery_apm_get_power_status;
  drivers/power/supply/apm_power.c:       apm_get_power_status = NULL;
  include/linux/apm-emulation.h:extern void (*apm_get_power_status)(struct apm_power_info *);

All of them are compatible with the API (post-remove UAFs notwithstanding)
and don't even read it except to compare with their own values;
on a cursory glance this doesn't seem to have ever not been the case.

Fixes: 7726942fb15e ("[APM] Add shared version of APM emulation")
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@...ijaczleweli.xyz>
---
 drivers/char/apm-emulation.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c
index 53ce352f7197..4aa5d1c76f83 100644
--- a/drivers/char/apm-emulation.c
+++ b/drivers/char/apm-emulation.c
@@ -142,18 +142,10 @@ static struct apm_queue kapmd_queue;
 static DEFINE_MUTEX(state_lock);
 
 
-/*
- * Compatibility cruft until the IPAQ people move over to the new
- * interface.
- */
-static void __apm_get_power_status(struct apm_power_info *info)
-{
-}
-
 /*
  * This allows machines to provide their own "apm get power status" function.
  */
-void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
+void (*apm_get_power_status)(struct apm_power_info *);
 EXPORT_SYMBOL(apm_get_power_status);
 
 
-- 
2.39.5

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