From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1731180-1526348297-2-6073342790882554611 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.249, MAILING_LIST_MULTI -1, RCVD_IN_DNSWL_MED -2.3, SPF_PASS -0.001, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='140.211.166.136', Host='smtp3.osuosl.org', Country='US', FromHeader='com', MailFrom='org' X-Spam-charsets: plain='us-ascii' X-Attached: signature.asc X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: driverdev-devel-bounces@linuxdriverproject.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=fm2; t= 1526348296; b=maPiAwXc/Ncg6v/yoIigImyfzuDU0etx9hbE6AY/pc2B9lIGCB V09bo8GEm+bmjUz8lo05Oi9CjoJqlcryX0BZKifbJUwvHbEb0LSh1zmaQEmYaCU9 xB1wnsNbYQWBWnTRobwa2DHWiKaAgD/R2YrzSmA2DoJySpzcfXH68eEQ4ssWLTuP isORIUmylwjy0qWJnAUb4r1wQ8Logqu+1iQD5CBCNBOyknnQf40lVQoIEw1tyi40 84GJ+9a6eWRetXKqtjzrw122R3nt1PDZ7Ag0QApnpNe4O6LgnobveQUq4B8xQaaI /hKi+NJYcmEmzm/m5o7HMvR4zTmfGbPq+rqA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:date:subject:in-reply-to :references:message-id:mime-version:list-id:list-unsubscribe :list-archive:list-post:list-help:list-subscribe:cc:content-type :sender; s=fm2; t=1526348296; bh=FvozX8pUAG1uqxDZTarkob/PRg2KA9d X32QDiEVZflw=; b=PV4Fc8lcvOjAEJIfrnUszyXAAXI9Bpz2kZHYgrBj1zVVFGg 3Rv9QWjBVS8iAp3+UbwftC9TjECmdC+m8uak+Sh5jM9Idvh9dCcRTd7ZcSigzQfn Gb3lCm2YUnhHj0/HZi2pjvEQZhDVdXcGWlT0REp19RkyIuuyZPaL4rEdfIh7zUVu E2kxcSyJvLDsgm+F0UNZNSSQRSWfAPRz6HPCVGSiLlauNsFoaFbzlN1tWUpzWOS+ ehqTqyesxFOJF58KjZTYRtS9NEAO2LhEJet9r/8CHtiMgN26H3fvXkRRrHAeA9Av i9P1/M3WSqJVn2rOriHJ/A5HzY2ouwZU4odDpaA== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=suse.com; iprev=pass policy.iprev=140.211.166.136 (smtp3.osuosl.org); spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org smtp.helo=silver.osuosl.org; x-aligned-from=fail; x-cm=discussion score=0; x-ptr=fail x-ptr-helo=silver.osuosl.org x-ptr-lookup=smtp3.osuosl.org; x-return-mx=pass smtp.domain=linuxdriverproject.org smtp.result=pass smtp_is_org_domain=yes header.domain=suse.com header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128; x-vs=clean score=-100 state=0 Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=suse.com; iprev=pass policy.iprev=140.211.166.136 (smtp3.osuosl.org); spf=pass smtp.mailfrom=driverdev-devel-bounces@linuxdriverproject.org smtp.helo=silver.osuosl.org; x-aligned-from=fail; x-cm=discussion score=0; x-ptr=fail x-ptr-helo=silver.osuosl.org x-ptr-lookup=smtp3.osuosl.org; x-return-mx=pass smtp.domain=linuxdriverproject.org smtp.result=pass smtp_is_org_domain=yes header.domain=suse.com header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfJ+G4J50xgA3kVoBGURNza00NflkT0Ptqh4cMdD8H02IeMpO4ZdwgbsQ+cY4tlRiCDCVRYqdXEXP80r66PZ2LeR+J5sjJxR79cVInPfW+Tn9F9XCvaOq 0iNVEsu/CcCSPsz1s3eeIANIZnJ8mT3xftzhCsz60f2RnYiFpXlGNt/eB+ITKRUP5cWBJXYwuqR9rRlbNlTkTu+PH87vvIvtmyP2uhaP0z4EzQTSK5X2Qz/C 9IcGoThYhYKGQbACmrHwbQ== X-CM-Analysis: v=2.3 cv=WaUilXpX c=1 sm=1 tr=0 a=FmzrR3azffoSx43hyxYGHg==:117 a=FmzrR3azffoSx43hyxYGHg==:17 a=1oJP67jkp3AA:10 a=VUJBJC2UJ8kA:10 a=-uNXE31MpBQA:10 a=jJxKW8Ag-pUA:10 a=ZZnuYtJkoWoA:10 a=QyXUC8HyAAAA:8 a=axGCdCNIJr2STHn6GGMA:9 a=WI3ZHISeKM_Q-7cycVcA:9 a=ONNS8QRKHyMA:10 a=DDOyTI_5AAAA:8 a=w27ZC7bHMYj9Vt11HkIA:9 a=CjuIK1q_8ugA:10 a=pC-h2on8RWMA:10 a=_BcfOz0m4U4ohdxiHPKc:22 cc=dsc X-ME-CMScore: 0 X-ME-CMCategory: discussion X-Remote-Delivered-To: driverdev-devel@osuosl.org From: NeilBrown To: James Simmons Date: Tue, 15 May 2018 11:37:56 +1000 Subject: Re: [PATCH 4/4] staging: lustre: obdclass: change object lookup to no wait mode In-Reply-To: References: <1525285308-15347-1-git-send-email-jsimmons@infradead.org> <1525285308-15347-5-git-send-email-jsimmons@infradead.org> <876044fcgg.fsf@notabene.neil.brown.name> Message-ID: <87efid7l6z.fsf@notabene.neil.brown.name> MIME-Version: 1.0 X-BeenThere: driverdev-devel@linuxdriverproject.org X-Mailman-Version: 2.1.24 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devel@driverdev.osuosl.org, Andreas Dilger , Greg Kroah-Hartman , Linux Kernel Mailing List , Oleg Drokin , Jinshan Xiong , Lai Siyao , Lustre Development List Content-Type: multipart/mixed; boundary="===============6170230028288820310==" Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: --===============6170230028288820310== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, May 15 2018, James Simmons wrote: >> On Wed, May 02 2018, James Simmons wrote: >>=20 >> > From: Lai Siyao >> > >> > Currently we set LU_OBJECT_HEARD_BANSHEE on object when we want >> > to remove object from cache, but this may lead to deadlock, because >> > when other process lookup such object, it needs to wait for this >> > object until release (done at last refcount put), while that process >> > maybe already hold an LDLM lock. >> > >> > Now that current code can handle dying object correctly, we can just >> > return such object in lookup, thus the above deadlock can be avoided. >>=20 >> I think one of the reasons that I didn't apply this to mainline myself >> is that "Now that" comment. When is the "now" that it is referring to? >> Are were sure that all code in mainline "can handle dying objects >> correctly"?? > > So I talked to Lai and he posted the LU-9049 ticket what patches need to > land before this one. Only one patch is of concern and its for LU-9203 > which doesn't apply to the staging tree since we don't have the LNet SMP > updates in our tree. I saved notes about making sure LU-9203 lands=20 > together with the future LNet SMP changes. As it stands it is safe to > land to staging. Thanks a lot for looking into this. Nice to have the safety of this change confirmed. What do you think of: >> > @@ -713,36 +691,46 @@ struct lu_object *lu_object_find_at(const struct= lu_env *env, >> > * It is unnecessary to perform lookup-alloc-lookup-insert, instead, >> > * just alloc and insert directly. >> > * >> > + * If dying object is found during index search, add @waiter to the >> > + * site wait-queue and return ERR_PTR(-EAGAIN). >>=20 >> It seems odd to add this comment here, when it seems to describe code >> that is being removed. >> I can see that this comment is added by the upstream patch >> Commit: fa14bdf6b648 ("LU-9049 obdclass: change object lookup to no wait= mode") >> but I cannot see what it refers to. >>=20 ?? Am I misunderstanding something, or is that comment wrong? Thanks, NeilBrown --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlr6OfQACgkQOeye3VZi gbl7RA//VDzBj1UncUhWv/9vthIv2Vm46k/h5SN4iAmnnIaVRNVWcKkGyoCj62hQ e1Q1fJ83Xbe2xkEWiuYhjoKd8fJWsG1eaxxlNI6HWEEv1BxbmHyhjYIQ3RbaIapA wf9GIU2q21CMUvLsGlrLb+yN9Upa10Vyb9LNKqenLq9C9yxKBHy12F7d0XYYUQ6H js8IjlUWsWO8NgOKzb4WnDbHW3iKIpHISpxaLHvkmA8oLm8dkC6NqLyLkDa1n3Fz lyZrxeMyx/caZf4ePeyendU4zBnnIuKbTU4GhnAyPaYVfRfrXxqI0JZqje5XxM/y J+rZ/5Uxhgg7rH+q3Y5+Xeadn9MhbZRxbGWJn//S6IA8Y1lEjRbrU/VbTQrBu2kN E3xuYtX71oaJOf9iwnBl5oCs81LT7qVNYBUV4cbawJ9EPVVKVpDx5G6jBWH0utyk 5/eGdTCKpjrxf+f25zXfS47KQL/7tPwuCHyJSocHrnE7DMwE/FEgbDu/KTjIP0zG wUROiDsA/x1oKlKBMTwBnLPqmxL2CSkCZq5ptsf+iuUZqBboE6dPX4Yqt8K5YFJc h52wPp50BrFaMs6lsmhPdO7wYBFIAQtvVVFvA8Puyc/8sTma9PZoWW/NrJu3n9RJ AVSnSD75SWaVrnfrR+tZKYF31rjG0qJAhx3FJjV5MY/k1N+fqK0= =8ybm -----END PGP SIGNATURE----- --=-=-=-- --===============6170230028288820310== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel --===============6170230028288820310==--