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| author | Matthias Maennich <maennich@google.com> | 2019-09-06 11:32:30 +0100 |
|---|---|---|
| committer | Jessica Yu <jeyu@kernel.org> | 2019-09-10 10:30:31 +0200 |
| commit | 8e2adc6a00cd96c07fcfa8adfbedbb4be681b8a7 (patch) | |
| tree | 419b3b83556b171a12b3f1a8784cb498c664974e /include/linux/export.h | |
| parent | 3d52ec5e5d0dd7f8ca96a68c6756bd96e58b716b (diff) | |
| download | lwn-8e2adc6a00cd96c07fcfa8adfbedbb4be681b8a7.tar.gz lwn-8e2adc6a00cd96c07fcfa8adfbedbb4be681b8a7.zip | |
export: allow definition default namespaces in Makefiles or sources
To avoid excessive usage of EXPORT_SYMBOL_NS(sym, MY_NAMESPACE), where
MY_NAMESPACE will always be the namespace we are exporting to, allow
exporting all definitions of EXPORT_SYMBOL() and friends by defining
DEFAULT_SYMBOL_NAMESPACE.
For example, to export all symbols defined in usb-common into the
namespace USB_COMMON, add a line like this to drivers/usb/common/Makefile:
ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE=USB_COMMON
That is equivalent to changing all EXPORT_SYMBOL(sym) definitions to
EXPORT_SYMBOL_NS(sym, USB_COMMON). Subsequently all symbol namespaces
functionality will apply.
Another way of making use of this feature is to define the namespace
within source or header files similar to how TRACE_SYSTEM defines are
used:
#undef DEFAULT_SYMBOL_NAMESPACE
#define DEFAULT_SYMBOL_NAMESPACE USB_COMMON
Please note that, as opposed to TRACE_SYSTEM, DEFAULT_SYMBOL_NAMESPACE
has to be defined before including include/linux/export.h.
If DEFAULT_SYMBOL_NAMESPACE is defined, a symbol can still be exported
to another namespace by using EXPORT_SYMBOL_NS() and friends with
explicitly specifying the namespace.
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Martijn Coenen <maco@android.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Diffstat (limited to 'include/linux/export.h')
| -rw-r--r-- | include/linux/export.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/export.h b/include/linux/export.h index d59461e71478..2c5468d8ea9a 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -166,6 +166,12 @@ struct kernel_symbol { #define __EXPORT_SYMBOL ___EXPORT_SYMBOL #endif +#ifdef DEFAULT_SYMBOL_NAMESPACE +#undef __EXPORT_SYMBOL +#define __EXPORT_SYMBOL(sym, sec) \ + __EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE) +#endif + #define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") #define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") #define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") |