From owner-freebsd-current@freebsd.org Mon Apr 19 10:00:15 2021 Return-Path: Delivered-To: freebsd-current@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 6F1865EB750 for ; Mon, 19 Apr 2021 10:00:15 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4FP2PB2mChz3jN7; Mon, 19 Apr 2021 10:00:14 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.16.1/8.16.1) with ESMTPS id 13JA02bl074528 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 19 Apr 2021 13:00:05 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua 13JA02bl074528 Received: (from kostik@localhost) by tom.home (8.16.1/8.16.1/Submit) id 13JA02Or074522; Mon, 19 Apr 2021 13:00:02 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Mon, 19 Apr 2021 13:00:02 +0300 From: Konstantin Belousov To: Alexander Richardson Cc: =?utf-8?B?0JDQu9C10LrRgdCw0L3QtNGAINCd0LXQtNC+0YbRg9C60L7Qsg==?= , freebsd-current , Brad Davis Subject: Re: NSS issues after locking fixes Message-ID: References: <2160831618773765@mail.yandex.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FROM, NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on tom.home X-Rspamd-Queue-Id: 4FP2PB2mChz3jN7 X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=gmail.com (policy=none); spf=softfail (mx1.freebsd.org: 2001:470:d5e7:1::1 is neither permitted nor denied by domain of kostikbel@gmail.com) smtp.mailfrom=kostikbel@gmail.com X-Spamd-Result: default: False [-1.00 / 15.00]; ARC_NA(0.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; FREEMAIL_FROM(0.00)[gmail.com]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; HAS_XAW(0.00)[]; RBL_DBL_DONT_QUERY_IPS(0.00)[2001:470:d5e7:1::1:from]; R_SPF_SOFTFAIL(0.00)[~all:c]; NEURAL_SPAM_SHORT(1.00)[1.000]; RBL_SENDERSCORE_FAIL(0.00)[2001:470:d5e7:1::1:server fail]; SPAMHAUS_ZRD(0.00)[2001:470:d5e7:1::1:from:127.0.2.255]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; MAILMAN_DEST(0.00)[freebsd-current]; DMARC_POLICY_SOFTFAIL(0.10)[gmail.com : No valid SPF, No valid DKIM,none] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Apr 2021 10:00:15 -0000 On Mon, Apr 19, 2021 at 10:06:28AM +0100, Alexander Richardson wrote: > On Sun, 18 Apr 2021 at 20:58, Александр Недоцуков wrote: > > > > Hi All, > > > > After supposed locking fixes done in this commit: 5245bf7b92b74e556527b4916a8deba386fe5772 > > we have a broken nsdispatch(3) when system has a threaded nss module plugged in. > > > > To illustrate the problem: > > > > $id bland > > id: bland: no such user > > t$LD_PRELOAD=/usr/lib/libthr.so id bland > > uid=1001(bland) gid=500(domainusers) groups=500(domainusers),... > > > > $cat /etc/nsswitch.conf > > group: files ldap > > hosts: files mdns dns > > netgroup: comapt > > networks: files > > passwd: files ldap > > shells: files > > services: files > > protocols: files > > rpc: files > > > > It seems that the commit in question was done under asumption that threading model can never be changed during run-time, while previous code was taking care of it by taking a copy of __isthreaded. > > > > I can not reach out Alex Rechardson who authored this change. Perhaps someone else can step in and take care of it? > > > > Thanks, > > Alexander. > > Hi Alexander, > > I was away over the weekend so I wasn't able to revert it then. I've > committed the revert as > https://cgit.freebsd.org/src/commit/?id=738314e445ceac4d3dd6c77c636044141623b8dc > and > > I am not convinced that __isthreaded changing is the real problem. > This can only happen with fork() (which calls _thr_setthreaded(0)) > since if it's currently false, the main thread is executing and we > can't be spawning a new thread. > I think the problem could be that fork() is called while the lock is > held in one thread and therefore the new process ends up with a locked > rwlock. I think the solution could be to add a pthread_atfork() > callback that unlocks the rwlock. Just to be pedantic. Proper way to handle process-private locks and fork is to lock in pthread_atfork prepare(), and unlock both in parent and child.