57  * The fasttrap provider allows DTrace consumers to instrument any user-level
106  * framework -- is a little tricky and bears some explanation. Each provider
109  * (ftp_ccount) and USDT consumers (ftp_mcount); all three prevent a provider
110  * from being freed. A provider is looked up by taking the bucket lock for the
111  * provider hash table, and is returned with its lock held. The provider lock
117  * not be taken when holding the provider lock as that would create a cyclic
118  * lock ordering. In situations where one would naturally take the provider
120  * the provider from disappearing, drop the provider lock, and acquire the
124  * 	bucket lock before provider lock
125  *	DTrace before provider lock
127  *	never hold the provider lock and creation lock simultaneously
143  * When the fasttrap provider is loaded, fasttrap_max is set to either
294 		 * ones. If a provider is marked but not retired, we just  in fasttrap_pid_cleanup_cb()
312 				 * If this provider has consumers actively  in fasttrap_pid_cleanup_cb()
314 				 * provider (ftp_mcount), we can't unregister  in fasttrap_pid_cleanup_cb()
331 				 * provider we can remove it from the hash  in fasttrap_pid_cleanup_cb()
334 				 * provider, increment our flag to try again  in fasttrap_pid_cleanup_cb()
364 	 * If we were unable to remove a retired provider, try again after  in fasttrap_pid_cleanup_cb()
454 				 * exit, and removal of a meta provider so it  in fasttrap_fork()
470  * is set on the proc structure to indicate that there is a pid provider
482 	 * We clean up the pid provider for this process here; user-land  in fasttrap_exec_exit()
483 	 * static probes are handled by the meta-provider remove entry point.  in fasttrap_exec_exit()
542 		 * provider (this one) will still be around throughout this  in fasttrap_tracepoint_enable()
677 	fasttrap_provider_t *provider = probe->ftp_prov;  in fasttrap_tracepoint_disable()  local
699 		    tp->ftt_proc == provider->ftp_proc)  in fasttrap_tracepoint_disable()
792 	 * live or we hold the provider lock on the process if it's dead and  in fasttrap_tracepoint_disable()
902 	 * Increment the count of enabled probes on this probe's provider;  in fasttrap_pid_enable()
903 	 * the provider can't go away while the probe still exists. We  in fasttrap_pid_enable()
912 	 * If this probe's provider is retired (meaning it was valid in a  in fasttrap_pid_enable()
914 	 * provider can't go away while we're in this code path.  in fasttrap_pid_enable()
1014 	fasttrap_provider_t *provider = probe->ftp_prov;  in fasttrap_pid_disable()  local
1023 	 * provider lock as a point of mutual exclusion to prevent other  in fasttrap_pid_disable()
1031 	mutex_enter(&provider->ftp_mtx);  in fasttrap_pid_disable()
1042 	ASSERT(provider->ftp_rcount > 0);  in fasttrap_pid_disable()
1043 	provider->ftp_rcount--;  in fasttrap_pid_disable()
1048 		 * mark this retired provider to get a chance to remove some  in fasttrap_pid_disable()
1051 		if (provider->ftp_retired && !provider->ftp_marked)  in fasttrap_pid_disable()
1052 			whack = provider->ftp_marked = 1;  in fasttrap_pid_disable()
1053 		mutex_exit(&provider->ftp_mtx);  in fasttrap_pid_disable()
1062 		if (provider->ftp_rcount == 0 && !provider->ftp_marked)  in fasttrap_pid_disable()
1063 			whack = provider->ftp_marked = 1;  in fasttrap_pid_disable()
1064 		mutex_exit(&provider->ftp_mtx);  in fasttrap_pid_disable()
1292  * Lookup a fasttrap-managed provider based on its name and associated pid.
1293  * If the pattr argument is non-NULL, this function instantiates the provider
1294  * if it doesn't exist otherwise it returns NULL. The provider is returned
1350 	 * when we're done with this provider.  in fasttrap_provider_lookup()
1373 	 * Take another lap through the list to make sure a provider hasn't  in fasttrap_provider_lookup()
1390 	 * Fail and return NULL if either the provider name is too long  in fasttrap_provider_lookup()
1391 	 * or we fail to register this new provider with the DTrace  in fasttrap_provider_lookup()
1393 	 * the full provider name -- we keep it in pieces in the provider  in fasttrap_provider_lookup()
1419 fasttrap_provider_free(fasttrap_provider_t *provider)  in fasttrap_provider_free()  argument
1421 	pid_t pid = provider->ftp_pid;  in fasttrap_provider_free()
1426 	 * creating probes, and no meta providers referencing this provider.  in fasttrap_provider_free()
1428 	ASSERT(provider->ftp_rcount == 0);  in fasttrap_provider_free()
1429 	ASSERT(provider->ftp_ccount == 0);  in fasttrap_provider_free()
1430 	ASSERT(provider->ftp_mcount == 0);  in fasttrap_provider_free()
1433 	 * If this provider hasn't been retired, we need to explicitly drop the  in fasttrap_provider_free()
1436 	if (!provider->ftp_retired) {  in fasttrap_provider_free()
1437 		atomic_dec_64(&provider->ftp_proc->ftpc_acount);  in fasttrap_provider_free()
1438 		ASSERT(provider->ftp_proc->ftpc_acount <  in fasttrap_provider_free()
1439 		    provider->ftp_proc->ftpc_rcount);  in fasttrap_provider_free()
1442 	fasttrap_proc_release(provider->ftp_proc);  in fasttrap_provider_free()
1444 	kmem_free(provider, sizeof (fasttrap_provider_t));  in fasttrap_provider_free()
1447 	 * Decrement p_dtrace_probes on the process whose provider we're  in fasttrap_provider_free()
1450 	 * corresponds to this process's hash chain in the provider hash  in fasttrap_provider_free()
1498 	 * Mark the provider to be removed in our post-processing step, mark it  in fasttrap_provider_retire()
1501 	 * that we're done with this provider; dropping the active the proc  in fasttrap_provider_retire()
1505 	 * We obviously need to take the bucket lock before the provider lock  in fasttrap_provider_retire()
1506 	 * to perform the lookup, but we need to drop the provider lock  in fasttrap_provider_retire()
1508 	 * provider lock in callbacks invoked from the DTrace framework. The  in fasttrap_provider_retire()
1509 	 * bucket lock therefore protects the integrity of the provider hash  in fasttrap_provider_retire()
1521 	 * We don't have to worry about invalidating the same provider twice  in fasttrap_provider_retire()
1522 	 * since fasttrap_provider_lookup() will ignore provider that have  in fasttrap_provider_retire()
1547 	fasttrap_provider_t *provider;  in fasttrap_add_probe()  local
1575 	if ((provider = fasttrap_provider_lookup(pdata->ftps_pid,  in fasttrap_add_probe()
1581 	 * actively adding a new probe associated with this provider. This  in fasttrap_add_probe()
1582 	 * prevents the provider from being deleted -- we'll need to check  in fasttrap_add_probe()
1585 	provider->ftp_ccount++;  in fasttrap_add_probe()
1586 	mutex_exit(&provider->ftp_mtx);  in fasttrap_add_probe()
1591 	 * other threads creating probes. We must drop the provider lock  in fasttrap_add_probe()
1595 	mutex_enter(&provider->ftp_cmtx);  in fasttrap_add_probe()
1604 			if (dtrace_probe_lookup(provider->ftp_provid,  in fasttrap_add_probe()
1617 			pp->ftp_prov = provider;  in fasttrap_add_probe()
1626 			tp->ftt_proc = provider->ftp_proc;  in fasttrap_add_probe()
1634 			pp->ftp_id = dtrace_probe_create(provider->ftp_provid,  in fasttrap_add_probe()
1639 	} else if (dtrace_probe_lookup(provider->ftp_provid, pdata->ftps_mod,  in fasttrap_add_probe()
1667 		pp->ftp_prov = provider;  in fasttrap_add_probe()
1677 			tp->ftt_proc = provider->ftp_proc;  in fasttrap_add_probe()
1686 		pp->ftp_id = dtrace_probe_create(provider->ftp_provid,  in fasttrap_add_probe()
1690 	mutex_exit(&provider->ftp_cmtx);  in fasttrap_add_probe()
1693 	 * We know that the provider is still valid since we incremented the  in fasttrap_add_probe()
1694 	 * creation reference count. If someone tried to clean up this provider  in fasttrap_add_probe()
1698 	mutex_enter(&provider->ftp_mtx);  in fasttrap_add_probe()
1699 	provider->ftp_ccount--;  in fasttrap_add_probe()
1700 	whack = provider->ftp_retired;  in fasttrap_add_probe()
1701 	mutex_exit(&provider->ftp_mtx);  in fasttrap_add_probe()
1711 	 * this provider to free some up. This is to cover the case where  in fasttrap_add_probe()
1715 	mutex_exit(&provider->ftp_cmtx);  in fasttrap_add_probe()
1716 	mutex_enter(&provider->ftp_mtx);  in fasttrap_add_probe()
1717 	provider->ftp_ccount--;  in fasttrap_add_probe()
1718 	provider->ftp_marked = 1;  in fasttrap_add_probe()
1719 	mutex_exit(&provider->ftp_mtx);  in fasttrap_add_probe()
1730 	fasttrap_provider_t *provider;  in fasttrap_meta_provide()  local
1735 	 * have enough space for the provider name.  in fasttrap_meta_provide()
1738 	    sizeof (provider->ftp_name)) {  in fasttrap_meta_provide()
1739 		cmn_err(CE_WARN, "failed to instantiate provider %s: "  in fasttrap_meta_provide()
1745 	 * Don't let folks spoof the true pid provider.  in fasttrap_meta_provide()
1748 		cmn_err(CE_WARN, "failed to instantiate provider %s: "  in fasttrap_meta_provide()
1756 	 * the stability of the new provider accordingly.  in fasttrap_meta_provide()
1769 	if ((provider = fasttrap_provider_lookup(pid, dhpv->dthpv_provname,  in fasttrap_meta_provide()
1771 		cmn_err(CE_WARN, "failed to instantiate provider %s for "  in fasttrap_meta_provide()
1777 	 * Up the meta provider count so this provider isn't removed until  in fasttrap_meta_provide()
1778 	 * the meta provider has been told to remove it.  in fasttrap_meta_provide()
1780 	provider->ftp_mcount++;  in fasttrap_meta_provide()
1782 	mutex_exit(&provider->ftp_mtx);  in fasttrap_meta_provide()
1784 	return (provider);  in fasttrap_meta_provide()
1792 	fasttrap_provider_t *provider = parg;  in fasttrap_meta_create_probe()  local
1799 	 * Since the meta provider count is non-zero we don't have to worry  in fasttrap_meta_create_probe()
1800 	 * about this provider disappearing.  in fasttrap_meta_create_probe()
1802 	ASSERT(provider->ftp_mcount > 0);  in fasttrap_meta_create_probe()
1828 	mutex_enter(&provider->ftp_cmtx);  in fasttrap_meta_create_probe()
1830 	if (dtrace_probe_lookup(provider->ftp_provid, dhpb->dthpb_mod,  in fasttrap_meta_create_probe()
1832 		mutex_exit(&provider->ftp_cmtx);  in fasttrap_meta_create_probe()
1843 		mutex_exit(&provider->ftp_cmtx);  in fasttrap_meta_create_probe()
1849 	pp->ftp_prov = provider;  in fasttrap_meta_create_probe()
1850 	pp->ftp_pid = provider->ftp_pid;  in fasttrap_meta_create_probe()
1862 		tp->ftt_proc = provider->ftp_proc;  in fasttrap_meta_create_probe()
1864 		tp->ftt_pid = provider->ftp_pid;  in fasttrap_meta_create_probe()
1881 		tp->ftt_proc = provider->ftp_proc;  in fasttrap_meta_create_probe()
1883 		tp->ftt_pid = provider->ftp_pid;  in fasttrap_meta_create_probe()
1905 	pp->ftp_id = dtrace_probe_create(provider->ftp_provid, dhpb->dthpb_mod,  in fasttrap_meta_create_probe()
1908 	mutex_exit(&provider->ftp_cmtx);  in fasttrap_meta_create_probe()
1916 	 * Clean up the USDT provider. There may be active consumers of the  in fasttrap_meta_remove()
1917 	 * provider busy adding probes, no damage will actually befall the  in fasttrap_meta_remove()
1918 	 * provider until that count has dropped to zero. This just puts  in fasttrap_meta_remove()
1919 	 * the provider on death row.  in fasttrap_meta_remove()
2226 	 * Unregister the meta-provider to make sure no new fasttrap-  in fasttrap_detach()
2229 	 * meta-provider. We can fail to unregister as a meta-provider  in fasttrap_detach()
2271 			 * this provider. A thread must first acquire the  in fasttrap_detach()
2273 			 * blocking on the provider's lock.  in fasttrap_detach()