void
runtime·cgocall(void (*fn)(void*), void *arg)
{
Defer d;
if(m->racecall) {
runtime·asmcgocall(fn, arg);
return;
}
if(!runtime·iscgo && !Windows)
runtime·throw("cgocall unavailable");
if(fn == 0)
runtime·throw("cgocall nil");
if(raceenabled)
runtime·racereleasemerge(&cgosync);
// Create an extra M for callbacks on threads not created by Go on first cgo call.
if(runtime·needextram && runtime·cas(&runtime·needextram, 1, 0))
runtime·newextram();
m->ncgocall++;
/*
* Lock g to m to ensure we stay on the same stack if we do a
* cgo callback. Add entry to defer stack in case of panic.
*/
runtime·lockOSThread();
d.fn = &endcgoV;
d.siz = 0;
d.link = g->defer;
d.argp = (void*)-1; // unused because unlockm never recovers
d.special = true;
d.free = false;
g->defer = &d;
m->ncgo++;
/*
* Announce we are entering a system call
* so that the scheduler knows to create another
* M to run goroutines while we are in the
* foreign code.
*
* The call to asmcgocall is guaranteed not to
* split the stack and does not allocate memory,
* so it is safe to call while "in a system call", outside
* the $GOMAXPROCS accounting.
*/
runtime·entersyscall();
runtime·asmcgocall(fn, arg);
runtime·exitsyscall();
if(g->defer != &d || d.fn != &endcgoV)
runtime·throw("runtime: bad defer entry in cgocallback");
g->defer = d.link;
endcgo();
}
void
runtime·cgocallbackg(FuncVal *fn, void *arg, uintptr argsize)
{
Defer d;
if(m->racecall) {
reflect·call(fn, arg, argsize);
return;
}
if(g != m->curg)
runtime·throw("runtime: bad g in cgocallback");
runtime·exitsyscall(); // coming out of cgo call
if(m->needextram) {
m->needextram = 0;
runtime·newextram();
}
// Add entry to defer stack in case of panic.
d.fn = &unwindmf;
d.siz = 0;
d.link = g->defer;
d.argp = (void*)-1; // unused because unwindm never recovers
d.special = true;
d.free = false;
g->defer = &d;
if(raceenabled)
runtime·raceacquire(&cgosync);
// Invoke callback.
reflect·call(fn, arg, argsize);
if(raceenabled)
runtime·racereleasemerge(&cgosync);
// Pop defer.
// Do not unwind m->g0->sched.sp.
// Our caller, cgocallback, will do that.
if(g->defer != &d || d.fn != &unwindmf)
runtime·throw("runtime: bad defer entry in cgocallback");
g->defer = d.link;
runtime·entersyscall(); // going back to cgo call
}
void
runtime·cgocallbackg1(void)
{
CallbackArgs *cb;
Defer d;
if(m->needextram) {
m->needextram = 0;
runtime·newextram();
}
// Add entry to defer stack in case of panic.
d.fn = &unwindmf;
d.siz = 0;
d.link = g->defer;
d.argp = (void*)-1; // unused because unwindm never recovers
d.special = true;
d.free = false;
g->defer = &d;
if(raceenabled && !m->racecall)
runtime·raceacquire(&cgosync);
// Invoke callback.
cb = CBARGS;
runtime·newstackcall(cb->fn, cb->arg, cb->argsize);
if(raceenabled && !m->racecall)
runtime·racereleasemerge(&cgosync);
// Pop defer.
// Do not unwind m->g0->sched.sp.
// Our caller, cgocallback, will do that.
if(g->defer != &d || d.fn != &unwindmf)
runtime·throw("runtime: bad defer entry in cgocallback");
g->defer = d.link;
}