Revert commit 6797540c8b76 ("ASoC: cs-amp-lib: Use __free(kfree) instead
of manual freeing").

Krzysztof Kozlowski pointed out that __free() can be dangerous.
It can introduce new cleanup bugs. These are more subtle and difficult to
spot than a missing goto in traditional cleanup, because they are triggered
by writing regular idiomatic C code instead of using C++ conventions. As
it's regular C style it's more likely to be missed because the code is as
would be expected for C. The traditional goto also more obviously flags
to anyone changing the code in the future that they must be careful about
the cleanup.

We can just revert the change. There was nothing wrong with the original
code and as Krzysztof noted: "it does not make the code simpler."

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: 6797540c8b76 ("ASoC: cs-amp-lib: Use __free(kfree) instead of manual freeing")
---
 sound/soc/codecs/cs-amp-lib.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/sound/soc/codecs/cs-amp-lib.c b/sound/soc/codecs/cs-amp-lib.c
index 8c9fd9980a7d..d8f8b0259cd1 100644
--- a/sound/soc/codecs/cs-amp-lib.c
+++ b/sound/soc/codecs/cs-amp-lib.c
@@ -7,7 +7,6 @@
 
 #include <asm/byteorder.h>
 #include <kunit/static_stub.h>
-#include <linux/cleanup.h>
 #include <linux/debugfs.h>
 #include <linux/dev_printk.h>
 #include <linux/efi.h>
@@ -310,8 +309,9 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev,
 							     efi_guid_t **guid,
 							     u32 *attr)
 {
-	struct cirrus_amp_efi_data *efi_data __free(kfree) = NULL;
+	struct cirrus_amp_efi_data *efi_data;
 	unsigned long data_size = 0;
+	u8 *data;
 	efi_status_t status;
 	int i, ret;
 
@@ -339,18 +339,19 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev,
 	}
 
 	/* Get variable contents into buffer */
-	efi_data = kmalloc(data_size, GFP_KERNEL);
-	if (!efi_data)
+	data = kmalloc(data_size, GFP_KERNEL);
+	if (!data)
 		return ERR_PTR(-ENOMEM);
 
 	status = cs_amp_get_efi_variable(cs_amp_lib_cal_efivars[i].name,
 					 cs_amp_lib_cal_efivars[i].guid,
-					 attr, &data_size, efi_data);
+					 attr, &data_size, data);
 	if (status != EFI_SUCCESS) {
 		ret = -EINVAL;
 		goto err;
 	}
 
+	efi_data = (struct cirrus_amp_efi_data *)data;
 	dev_dbg(dev, "Calibration: Size=%d, Amp Count=%d\n", efi_data->size, efi_data->count);
 
 	if ((efi_data->count > 128) ||
@@ -364,9 +365,10 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev,
 	if (efi_data->size == 0)
 		efi_data->size = data_size;
 
-	return_ptr(efi_data);
+	return efi_data;
 
 err:
+	kfree(data);
 	dev_err(dev, "Failed to read calibration data from EFI: %d\n", ret);
 
 	return ERR_PTR(ret);
@@ -389,9 +391,9 @@ static int cs_amp_set_cal_efi_buffer(struct device *dev,
 static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid, int amp_index,
 					    struct cirrus_amp_cal_data *out_data)
 {
-	struct cirrus_amp_efi_data *efi_data __free(kfree) = NULL;
+	struct cirrus_amp_efi_data *efi_data;
 	struct cirrus_amp_cal_data *cal = NULL;
-	int i;
+	int i, ret;
 
 	efi_data = cs_amp_get_cal_efi_buffer(dev, NULL, NULL, NULL);
 	if (IS_ERR(efi_data))
@@ -432,14 +434,17 @@ static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid,
 			dev_warn(dev, "Calibration entry %d does not match silicon ID", amp_index);
 	}
 
-	if (!cal) {
+	if (cal) {
+		memcpy(out_data, cal, sizeof(*out_data));
+		ret = 0;
+	} else {
 		dev_warn(dev, "No calibration for silicon ID %#llx\n", target_uid);
-		return -ENOENT;
+		ret = -ENOENT;
 	}
 
-	memcpy(out_data, cal, sizeof(*out_data));
+	kfree(efi_data);
 
-	return 0;
+	return ret;
 }
 
 static int _cs_amp_set_efi_calibration_data(struct device *dev, int amp_index, int num_amps,
-- 
2.47.3

On Mon, 01 Dec 2025 11:14:29 +0000, Richard Fitzgerald wrote:
> Revert commit 6797540c8b76 ("ASoC: cs-amp-lib: Use __free(kfree) instead
> of manual freeing").
> 
> Krzysztof Kozlowski pointed out that __free() can be dangerous.
> It can introduce new cleanup bugs. These are more subtle and difficult to
> spot than a missing goto in traditional cleanup, because they are triggered
> by writing regular idiomatic C code instead of using C++ conventions. As
> it's regular C style it's more likely to be missed because the code is as
> would be expected for C. The traditional goto also more obviously flags
> to anyone changing the code in the future that they must be careful about
> the cleanup.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: cs-amp-lib: Revert use of __free(kfree) back to normal C cleanup
      commit: 2b69bee5a2d07bc0583f2a8f17d262ddf7c58466

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark