At Tue, 30 Jun 2009 10:20:54 +0400, Paul Fertser wrote:
On Tue, Jun 30, 2009 at 08:09:45AM +0200, Takashi Iwai wrote:
At Tue, 30 Jun 2009 02:11:01 +0400, Paul Fertser wrote:
I've tried to implement an external shared object to be able to execute arbitrary functions on PCM device opening and closing. After quite some source code reading i had an almost working but segfaulting example. This segfault is because snd_dlclose is called right after calling a hook install function and therefore i can't snd_pcm_hook_add functions from the same shared object. To me it looks like a bug but probably i just don't see how this functionality is intended to be used. Takashi, git-blame showed that it's you who stuffed this dlclose call that bothers me ;)
Well, right now, a plugin is designed to be bound with a single PCM instance. That's why dlcolse is called in snd_pcm_close().
It looks like we're talking about different things. You seem to be talking about external PCM plugins, i'm talking about external functions for the "hook" PCM plugin. The code i question is in pcm/pcm_hooks.c in function snd_pcm_hook_add_conf:
if (err >= 0) { if (args && snd_config_get_string(args, &str) >= 0) { err = snd_config_search_definition(root, "hook_args", str, &args); if (err < 0) SNDERR("unknown hook_args %s", str); else err = install_func(pcm, args); snd_config_delete(args); } else err = install_func(pcm, args); snd_dlclose(h); }
Ah, I understand now. Yes, this looks like a bug. Meanwhile, it makes another bug if we just remove it. There would be no dlclose(), then. It'd need resource tracking. A lack of dlclose is no serious bug, though.
So... just removing snd_dlclose() there fixes your problem? If yes, I'll commit the fix.
thanks,
Takashi