[PATCH 2/9] scripts/modpost: add a exception for USB gadget drivers

[Sebastian Andrzej Siewior]

The "driver" struct for a gadget driver is named *_driver. On module
load, the gadget expects a UDC driver to be loaded and avaiable. If this
is not the case => -ENODEV and bye bye. That means that the gadget
driver is initialized immediately. The initialization process includes
calling ->bind() for the gadget driver. Therefore it is okay to put this
in __init. It will never be called again, we don't (yet) allow two
gadgets of the same kind to be ->bind() again.

Commit 07a18bd716 ("usb gadget: don't save bind callback in struct
usb_composite_driver") move the ->bind() member from the struct to an
argument.
I'm reverting this and adding this exception. For g_zero we save around
400bytes. I'm not having the conversion about how important it is to
save 400 bytes. I wait for configfs interface for the gadget subsystem.
This will remove the __init from the ->bind() because we will be able to
call ->bind() more than once and _after_ the init has been dropped.

Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 scripts/mod/modpost.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 68e9f5e..5e30776 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -920,6 +920,9 @@ static const char *head_sections[] = { ".head.text*", NULL };
 static const char *linker_symbols[] =
 	{ "__init_begin", "_sinittext", "_einittext", NULL };
 
+static const char *const driver_sym[] = { "*_driver", NULL };
+static const char *const gadget_bind[] = { "*_bind", NULL };
+
 enum mismatch {
 	TEXT_TO_ANY_INIT,
 	DATA_TO_ANY_INIT,
@@ -1129,6 +1132,13 @@ static int secref_whitelist(const struct sectioncheck *mismatch,
 	    match(fromsym, mismatch->symbol_white_list))
 		return 0;
 
+	/* Check for pattern 2a */
+	if (match(tosec, init_exit_sections) &&
+	    match(fromsec, data_sections) &&
+	    match(fromsym, driver_sym) &&
+	    match(tosym, gadget_bind))
+		return 0;
+
 	/* Check for pattern 3 */
 	if (match(fromsec, head_sections) &&
 	    match(tosec, init_sections))
-- 
1.7.10.4

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