[PATCH] iio: osf: avoid a large stack frame in osf_core_init

[PATCH] iio: osf: avoid a large stack frame in osf_core_init

[Jinseob Kim]

Clang reports a 1344-byte stack frame in osf_core_init() for
hexagon-allmodconfig, exceeding CONFIG_FRAME_WARN=1280.

The aggregate assignment materializes a temporary struct osf_device on
the stack and copies it to the destination. With the mutex and caches
added by the IIO support, this structure is 1328 bytes in the reported
configuration.

Clear the destination directly, then set dev and initialize latest_lock
as before. This preserves zero initialization of all other fields,
including when the core is reinitialized for a new session, without the
large temporary object.

With the reported Clang 24.0.0git compiler and Hexagon configuration, the
frame decreases from 1344 to 8 bytes and the warning disappears.

Fixes: 7329986669f2 ("iio: osf: add IIO devices from capability reports")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202610191514.fRYyu0HX-lkp@intel.com/
Assisted-by: LLM
Signed-off-by: Jinseob Kim <kimjinseob88@gmail.com>
---
 drivers/iio/sensorhubs/osf/osf_core.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/sensorhubs/osf/osf_core.c b/drivers/iio/sensorhubs/osf/osf_core.c
index 4f73ff5e9572..62b086f67e6f 100644
--- a/drivers/iio/sensorhubs/osf/osf_core.c
+++ b/drivers/iio/sensorhubs/osf/osf_core.c
@@ -16,9 +16,8 @@
 
 void osf_core_init(struct osf_device *osf, struct device *dev)
 {
-	*osf = (struct osf_device) {
-		.dev = dev,
-	};
+	memset(osf, 0, sizeof(*osf));
+	osf->dev = dev;
 	mutex_init(&osf->latest_lock);
 }
 

base-commit: 43ffda3c7f8456bbe641ae8249a077a361b97880
-- 
2.43.0

Re: [PATCH] iio: osf: avoid a large stack frame in osf_core_init

[Joshua Crofts]

On Mon, 19 Oct 2026 18:58:49 +0900
Jinseob Kim <kimjinseob88@gmail.com> wrote:

> Clang reports a 1344-byte stack frame in osf_core_init() for
> hexagon-allmodconfig, exceeding CONFIG_FRAME_WARN=1280.
> 
> The aggregate assignment materializes a temporary struct osf_device on
> the stack and copies it to the destination. With the mutex and caches
> added by the IIO support, this structure is 1328 bytes in the reported
> configuration.
> 
> Clear the destination directly, then set dev and initialize latest_lock
> as before. This preserves zero initialization of all other fields,
> including when the core is reinitialized for a new session, without the
> large temporary object.
> 
> With the reported Clang 24.0.0git compiler and Hexagon configuration, the
> frame decreases from 1344 to 8 bytes and the warning disappears.
> 
> Fixes: 7329986669f2 ("iio: osf: add IIO devices from capability reports")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202610191514.fRYyu0HX-lkp@intel.com/
> Assisted-by: LLM
> Signed-off-by: Jinseob Kim <kimjinseob88@gmail.com>
> ---

Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>

-- 
Kind regards,
Joshua Crofts