[PATCH] Revert "i2c: core: Allocate temp client on the stack in i2c_detect"

From: Arnd Bergmann
Date: Fri Feb 21 2025 - 15:55:44 EST


From: Arnd Bergmann <arnd@xxxxxxxx>

struct i2c_client is way too large to be put on the kernel stack, and depending
on the kernel configuration, this can exceed the compile-time warning limit:

drivers/i2c/i2c-core-base.c:1420:12: error: stack frame size (1040) exceeds limit (1024) in 'i2c_do_add_adapter' [-Werror,-Wframe-larger-than]
1420 | static int i2c_do_add_adapter(struct i2c_driver *driver,
| ^

The current version is the result of a cleanup patch that does not appear
to be a requirement for anything else, so address the problem through a
simple revert.

Fixes: 735668f8e5c9 ("i2c: core: Allocate temp client on the stack in i2c_detect")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/i2c/i2c-core-base.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 35a221e2c11c..5c9419e95044 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -2506,7 +2506,7 @@ static int i2c_detect_address(struct i2c_client *temp_client,
static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
{
const unsigned short *address_list;
- struct i2c_client temp_client;
+ struct i2c_client *temp_client;
int i, err = 0;

address_list = driver->address_list;
@@ -2527,19 +2527,22 @@ static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
return 0;

/* Set up a temporary client to help detect callback */
- memset(&temp_client, 0, sizeof(temp_client));
- temp_client.adapter = adapter;
+ temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
+ if (!temp_client)
+ return -ENOMEM;
+ temp_client->adapter = adapter;

for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
dev_dbg(&adapter->dev,
"found normal entry for adapter %d, addr 0x%02x\n",
i2c_adapter_id(adapter), address_list[i]);
- temp_client.addr = address_list[i];
- err = i2c_detect_address(&temp_client, driver);
+ temp_client->addr = address_list[i];
+ err = i2c_detect_address(temp_client, driver);
if (unlikely(err))
break;
}

+ kfree(temp_client);
return err;
}

--
2.39.5