Re: [PATCH] rt2500usb: don't mark register accesses as inline

Arnd Bergmann [off-list ref] writes:

When CONFIG_KASAN is set, we get a rather large stack here:

drivers/net/wireless/ralink/rt2x00/rt2500usb.c: In function 'rt2500usb_set_device_state':
drivers/net/wireless/ralink/rt2x00/rt2500usb.c:1074:1: error: the frame size of 3032 bytes is larger than 100 bytes [-Werror=frame-larger-than=]

If we don't force those functions to be inline, the compiler can figure this
out better itself and not inline the functions when doing so would be harmful,
reducing the stack size to a merge 256 bytes.

Note that there is another problem that manifests in this driver, as a result
of the typecheck() macro causing even larger stack frames.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

[...]

-static inline void rt2500usb_register_multiread(struct rt2x00_dev *rt2x00dev,
-						const unsigned int offset,
-						void *value, const u16 length)
-{
-	rt2x00usb_vendor_request_buff(rt2x00dev, USB_MULTI_READ,
-				      USB_VENDOR_REQUEST_IN, offset,
-				      value, length);
-}
-

I guess you removed this because it was not actually used anywhere? Just
checking.

-- 
Kalle Valo

On Wed, Feb 15, 2017 at 6:49 AM, Kalle Valo [off-list ref] wrote:

Arnd Bergmann [off-list ref] writes:

quoted

When CONFIG_KASAN is set, we get a rather large stack here:

drivers/net/wireless/ralink/rt2x00/rt2500usb.c: In function 'rt2500usb_set_device_state':
drivers/net/wireless/ralink/rt2x00/rt2500usb.c:1074:1: error: the frame size of 3032 bytes is larger than 100 bytes [-Werror=frame-larger-than=]

If we don't force those functions to be inline, the compiler can figure this
out better itself and not inline the functions when doing so would be harmful,
reducing the stack size to a merge 256 bytes.

Note that there is another problem that manifests in this driver, as a result
of the typecheck() macro causing even larger stack frames.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

[...]

quoted

-static inline void rt2500usb_register_multiread(struct rt2x00_dev *rt2x00dev,
-                                             const unsigned int offset,
-                                             void *value, const u16 length)
-{
-     rt2x00usb_vendor_request_buff(rt2x00dev, USB_MULTI_READ,
-                                   USB_VENDOR_REQUEST_IN, offset,
-                                   value, length);
-}
-

I guess you removed this because it was not actually used anywhere? Just
checking.

Correct, if I just remove the 'inline' annotation, we get a warning about an
unused function here. Sorry for not mentioning that in the changelog.

    Arnd