[dylink] Remove redundant dlsync call. NFC

[sbc100]

dlsync is performed before returning from dlopen/dlsym. There is no needed pre-emptively call dlsync at the start of these operations.

[kripken]

dlsync is performed before returning from dlopen/dlsym.

Where is that call? Just scanning the rest of the functions here _dlopen and emscripten_dlopen I don't immediately see such a call.

There is no needed pre-emptively call dlsync at the start of these operations.

Can you explain why? Naively, I see a call to find_existing, and I'd guess it's good to sync and see if the library already exists?

[sbc100]

dlsync is performed before returning from dlopen/dlsym.

Where is that call? Just scanning the rest of the functions here _dlopen and emscripten_dlopen I don't immediately see such a call.

There is a call to dlsync in __dlsym itself on line 669.

There is a call to dlsync in load_library_done which is call once a dlopen call succeeds.

There is no needed pre-emptively call dlsync at the start of these operations.

Can you explain why? Naively, I see a call to find_existing, and I'd guess it's good to sync and see if the library already exists?

Once we get the write lock with do_write_lock there is now way for us to be out-of-sync with other threads. If another thread calls dlopen it won't release the write lock until all thread are in sync. If we got the write lock the we know the any outstanding sync calls much have completed already.

[kripken]

I see, thanks!