linux-kernel - [PATCH v2 1/1] cleanup: Fix sparse complaining about passing iomem ptr to no_free

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Message-Id: <20250310122158.20966-1-ilpo.jarvinen@linux.intel.com>
Date: Mon, 10 Mar 2025 14:21:58 +0200
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>,
	platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Rajneesh Bhardwaj <irenic.rajneesh@...il.com>,
	David E Box <david.e.box@...el.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Christian Brauner <brauner@...nel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Ingo Molnar <mingo@...nel.org>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	David Lechner <dlechner@...libre.com>,
	Uros Bizjak <ubizjak@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	kernel test robot <lkp@...el.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH v2 1/1] cleanup: Fix sparse complaining about passing iomem ptr to no_free_ptr()

Calling no_free_ptr() for an __iomem pointer results in sparse
complaining about the types:
  warning: incorrect type in argument 1 (different address spaces)
     expected void const volatile *val
     got void [noderef] __iomem *__val
(The example from drivers/platform/x86/intel/pmc/core_ssram.c:283).

The problem is caused by the signature of __must_check_fn() added in
the commit 85be6d842447 ("cleanup: Make no_free_ptr() __must_check") to
enforce return value is always used.

Use __force to allow both iomem and non-iomem pointers to be given for
no_free_ptr().

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403050547.qnZtuNlN-lkp@intel.com/
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---

I've no strong preferences through which tree this patch is routed.

v2:
- Rebased & updated line number to match the current code.

 include/linux/cleanup.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index ec00e3f7af2b..ee2614adb785 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -212,7 +212,7 @@ const volatile void * __must_check_fn(const volatile void *val)
 { return val; }
 
 #define no_free_ptr(p) \
-	((typeof(p)) __must_check_fn(__get_and_null(p, NULL)))
+	((typeof(p)) __must_check_fn((__force const volatile void *)__get_and_null(p, NULL)))
 
 #define return_ptr(p)	return no_free_ptr(p)
 

base-commit: 80e54e84911a923c40d7bee33a34c1b4be148d7a
-- 
2.39.5