[PATCH] firmware: cs_dsp: Remove __free() from cs_dsp_debugfs_string_read()

[PATCH] firmware: cs_dsp: Remove __free() from cs_dsp_debugfs_string_read()

[Richard Fitzgerald]

Don't use __free(kfree) in cs_dsp_debugfs_string_read. Instead use
normal kfree() to cleanup.

The use of __free() can create new cleanup bugs that are difficult to spot
because the defective code is idiomatically correct regular C. This
function used the suspect declaration __free(kfree) = NULL;.

The __free(kfree) didn't really do anything here. The function can be
rearranged to avoid any need to return or goto within the code.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: 3045e29d248b ("firmware: cs_dsp: Append \n to debugfs string during read")
---
 drivers/firmware/cirrus/cs_dsp.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/cirrus/cs_dsp.c b/drivers/firmware/cirrus/cs_dsp.c
index c2614de47107..d35d0f5ccaf7 100644
--- a/drivers/firmware/cirrus/cs_dsp.c
+++ b/drivers/firmware/cirrus/cs_dsp.c
@@ -375,18 +375,23 @@ static ssize_t cs_dsp_debugfs_string_read(struct cs_dsp *dsp,
 					  size_t count, loff_t *ppos,
 					  const char **pstr)
 {
-	const char *str __free(kfree) = NULL;
+	const char *str;
+	ssize_t ret = 0;
 
 	scoped_guard(mutex, &dsp->pwr_lock) {
-		if (!*pstr)
-			return 0;
-
-		str = kasprintf(GFP_KERNEL, "%s\n", *pstr);
-		if (!str)
-			return -ENOMEM;
-
-		return simple_read_from_buffer(user_buf, count, ppos, str, strlen(str));
+		if (*pstr) {
+			str = kasprintf(GFP_KERNEL, "%s\n", *pstr);
+			if (str) {
+				ret = simple_read_from_buffer(user_buf, count,
+							      ppos, str, strlen(str));
+				kfree(str);
+			} else {
+				ret = -ENOMEM;
+			}
+		}
 	}
+
+	return ret;
 }
 
 static ssize_t cs_dsp_debugfs_wmfw_read(struct file *file,
-- 
2.47.3

Re: [PATCH] firmware: cs_dsp: Remove __free() from cs_dsp_debugfs_string_read()

[Mark Brown]

On Tue, 02 Dec 2025 11:34:25 +0000, Richard Fitzgerald wrote:
> Don't use __free(kfree) in cs_dsp_debugfs_string_read. Instead use
> normal kfree() to cleanup.
> 
> The use of __free() can create new cleanup bugs that are difficult to spot
> because the defective code is idiomatically correct regular C. This
> function used the suspect declaration __free(kfree) = NULL;.
> 
> [...]

Applied to

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

Thanks!

[1/1] firmware: cs_dsp: Remove __free() from cs_dsp_debugfs_string_read()
      commit: 7a9fa7fda93b7b3ae515f40f67bbf8e1d16337e8

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