What is "#define alloc_ieee80211 alloc_ieee80211_rsl"?
Sorry I know what a #define is doing, but in this case I've no idea why it's used and what it's trying to achieve. This is from the rtl8192u driver in staging, where the alloc function (alloc_ieee80211) which is called by the probe function (rtl8192_usb_probe). So that's all good but a quick grep through the code and in the file drivers/staging/rtl8192u/ieee80211/ieee80211.h there's a line which defines that function as another function '_rsl' which don't exist anywhere in Kernel. #define alloc_ieee80211 alloc_ieee80211_rsl So what am I missing or why are a number of functions being redefined as another name, which doesn't exist? I'm tempted to remove any that don't exist but I should really find out what it is the lines are doing.
On Tue, Oct 09, 2018 at 08:07:08PM +0100, John Whitmore wrote:
Sorry I know what a #define is doing, but in this case I've no idea why it's used and what it's trying to achieve.
This is from the rtl8192u driver in staging, where the alloc function (alloc_ieee80211) which is called by the probe function (rtl8192_usb_probe). So that's all good but a quick grep through the code and in the file drivers/staging/rtl8192u/ieee80211/ieee80211.h there's a line which defines that function as another function '_rsl' which don't exist anywhere in Kernel.
#define alloc_ieee80211 alloc_ieee80211_rsl
So what am I missing or why are a number of functions being redefined as another name, which doesn't exist?
I'm tempted to remove any that don't exist but I should really find out what it is the lines are doing.
I should have held off for a few minutes. I removed all the '_rsl' defines from the code and the module re-builds so I think I'll just submit a patch. Unless somebody has a good reason not to.
On Tue, 09 Oct 2018 20:07:08 +0100, John Whitmore said:
#define alloc_ieee80211 alloc_ieee80211_rsl
So what am I missing or why are a number of functions being redefined as another name, which doesn't exist?
There's areas in the kernel which use the preprocessor ## to glue stuff together. see include/asm-generic/atomic-long.h and ATOMIC_LONG_FETCH_OP for an example. It's also use in some code to generate function names to initialize a structure of function pointers. This can make grepping for a function name troublesome if you don't realize there's ## abuse going on to create a function name on the fly. However, in this particular case, it looks like they're redirecting an allocator so that for rtl8192u, when common/copypasted code calls alloc_ieee80211 it gets redirected to their own version... [/usr/src/linux-next] git grep alloc_ieee80211 drivers/staging/rtl8192u/ieee80211/ieee80211.h:#define alloc_ieee80211 alloc_ieee80211_rsl drivers/staging/rtl8192u/ieee80211/ieee80211.h: * allocated beyond this structure by alloc_ieee80211 drivers/staging/rtl8192u/ieee80211/ieee80211.h:struct net_device *alloc_ieee80211(int sizeof_priv); drivers/staging/rtl8192u/ieee80211/ieee80211_module.c:struct net_device *alloc_ieee80211(int sizeof_priv) drivers/staging/rtl8192u/r8192U_core.c: dev = alloc_ieee80211(sizeof(struct r8192_priv));
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John Whitmore -
valdis.kletnieks＠vt.edu