Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754040Ab2K1KT0 (ORCPT ); Wed, 28 Nov 2012 05:19:26 -0500 Received: from merlin.infradead.org ([205.233.59.134]:48200 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753856Ab2K1KTZ (ORCPT ); Wed, 28 Nov 2012 05:19:25 -0500 Message-ID: <1354097960.21562.41.camel@shinybook.infradead.org> Subject: Re: [PATCH v3 8/7] pppoatm: fix missing wakeup in pppoatm_send() From: David Woodhouse To: Krzysztof Mazur Cc: chas williams - CONTRACTOR , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davem@davemloft.net Date: Wed, 28 Nov 2012 10:19:20 +0000 In-Reply-To: <20121128095843.GA8974@shrek.podlesie.net> References: <201211112257.qABMvhP4021769@thirdoffive.cmf.nrl.navy.mil> <1354022867.26346.334.camel@shinybook.infradead.org> <20121127102333.68ac3234@thirdoffive.cmf.nrl.navy.mil> <1354063697.21562.4.camel@shinybook.infradead.org> <20121128081237.GA30488@shrek.podlesie.net> <1354094649.21562.34.camel@shinybook.infradead.org> <20121128095843.GA8974@shrek.podlesie.net> Content-Type: multipart/signed; micalg="sha1"; protocol="application/x-pkcs7-signature"; boundary="=-VyX/Gs/GPavwzdwUwmHr" X-Mailer: Evolution 3.6.1 (3.6.1-1.fc18) Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11411 Lines: 200 --=-VyX/Gs/GPavwzdwUwmHr Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2012-11-28 at 10:58 +0100, Krzysztof Mazur wrote: > ok, I think that we should just drop that patch, with test_bit() > I think it's no longer an optimization. After another cup of tea, it now uses test_and_clear_bit()... and doesn't break the carefully crafted handling of the BLOCKED bit in the normal flow control case, by setting it at the nospace: label! =46rom b2cf6a466697ecf19061cb11b8f4ec5bb381550a Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Wed, 28 Nov 2012 10:15:05 +0000 Subject: [PATCH] pppoatm: optimise PPP channel wakeups after sock_owned_by_= user() We don't need to schedule the wakeup tasklet on *every* unlock; only if we actually blocked the channel in the first place. Signed-off-by: David Woodhouse --- net/atm/pppoatm.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c index 446a7f0..172e44e 100644 --- a/net/atm/pppoatm.c +++ b/net/atm/pppoatm.c @@ -113,7 +113,17 @@ static void pppoatm_release_cb(struct atm_vcc *atmvcc) { struct pppoatm_vcc *pvcc =3D atmvcc_to_pvcc(atmvcc); =20 - tasklet_schedule(&pvcc->wakeup_tasklet); + /* + * As in pppoatm_pop(), it's safe to clear the BLOCKED bit here because + * the wakeup *can't* race with pppoatm_send(). They both hold the PPP + * channel's ->downl lock. And the potential race with *setting* it, + * which leads to the double-check dance in pppoatm_may_send(), doesn't + * exist here. In the sock_owned_by_user() case in pppoatm_send(), we + * set the BLOCKED bit while the socket is still locked. We know that + * ->release_cb() can't be called until that's done. + */ + if (test_and_clear_bit(BLOCKED, &pvcc->blocked)) + tasklet_schedule(&pvcc->wakeup_tasklet); if (pvcc->old_release_cb) pvcc->old_release_cb(atmvcc); } @@ -292,8 +302,15 @@ static int pppoatm_send(struct ppp_channel *chan, stru= ct sk_buff *skb) =20 vcc =3D ATM_SKB(skb)->vcc; bh_lock_sock(sk_atm(vcc)); - if (sock_owned_by_user(sk_atm(vcc))) + if (sock_owned_by_user(sk_atm(vcc))) { + /* + * Needs to happen (and be flushed, hence test_and_) before we unlock + * the socket. It needs to be seen by the time our ->release_cb gets + * called. + */ + test_and_set_bit(BLOCKED, &pvcc->blocked); goto nospace; + } if (test_bit(ATM_VF_RELEASED, &vcc->flags) || test_bit(ATM_VF_CLOSE, &vcc->flags) || !test_bit(ATM_VF_READY, &vcc->flags)) { --=20 1.8.0 --=20 dwmw2 --=-VyX/Gs/GPavwzdwUwmHr Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIUbjCCBjQw ggQcoAMCAQICAR4wDQYJKoZIhvcNAQEFBQAwfTELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0 Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcxKTAn BgNVBAMTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4XDTA3MTAyNDIxMDE1NVoX DTE3MTAyNDIxMDE1NVowgYwxCzAJBgNVBAYTAklMMRYwFAYDVQQKEw1TdGFydENvbSBMdGQuMSsw KQYDVQQLEyJTZWN1cmUgRGlnaXRhbCBDZXJ0aWZpY2F0ZSBTaWduaW5nMTgwNgYDVQQDEy9TdGFy dENvbSBDbGFzcyAxIFByaW1hcnkgSW50ZXJtZWRpYXRlIENsaWVudCBDQTCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBAMcJg8zOLdgasSmkLhOrlr6KMoOMpohBllVHrdRvEg/q6r8jR+EK 75xCGhR8ToREoqe7zM9/UnC6TS2y9UKTpT1v7RSMzR0t6ndl0TWBuUr/UXBhPk+Kmy7bI4yW4urC +y7P3/1/X7U8ocb8VpH/Clt+4iq7nirMcNh6qJR+xjOhV+VHzQMALuGYn5KZmc1NbJQYclsGkDxD z2UbFqE2+6vIZoL+jb9x4Pa5gNf1TwSDkOkikZB1xtB4ZqtXThaABSONdfmv/Z1pua3FYxnCFmdr /+N2JLKutIxMYqQOJebr/f/h5t95m4JgrM3Y/w7YX9d7YAL9jvN4SydHsU6n65cCAwEAAaOCAa0w ggGpMA8GA1UdEwEB/wQFMAMBAf8wDgYDVR0PAQH/BAQDAgEGMB0GA1UdDgQWBBRTcu2SnODaywFc fH6WNU7y1LhRgjAfBgNVHSMEGDAWgBROC+8apEBbpRdphzDKNGhD0EGu8jBmBggrBgEFBQcBAQRa MFgwJwYIKwYBBQUHMAGGG2h0dHA6Ly9vY3NwLnN0YXJ0c3NsLmNvbS9jYTAtBggrBgEFBQcwAoYh aHR0cDovL3d3dy5zdGFydHNzbC5jb20vc2ZzY2EuY3J0MFsGA1UdHwRUMFIwJ6AloCOGIWh0dHA6 Ly93d3cuc3RhcnRzc2wuY29tL3Nmc2NhLmNybDAnoCWgI4YhaHR0cDovL2NybC5zdGFydHNzbC5j b20vc2ZzY2EuY3JsMIGABgNVHSAEeTB3MHUGCysGAQQBgbU3AQIBMGYwLgYIKwYBBQUHAgEWImh0 dHA6Ly93d3cuc3RhcnRzc2wuY29tL3BvbGljeS5wZGYwNAYIKwYBBQUHAgEWKGh0dHA6Ly93d3cu c3RhcnRzc2wuY29tL2ludGVybWVkaWF0ZS5wZGYwDQYJKoZIhvcNAQEFBQADggIBAAqDCH14qywG XLhjjF6uHLkjd02hcdh9hrw+VUsv+q1eeQWB21jWj3kJ96AUlPCoEGZ/ynJNScWy6QMVQjbbMXlt UfO4n4bGGdKo3awPWp61tjAFgraLJgDk+DsSvUD6EowjMTNx25GQgyYJ5RPIzKKR9tQW8gGK+2+R HxkUCTbYFnL6kl8Ch507rUdPPipJ9CgJFws3kDS3gOS5WFMxcjO5DwKfKSETEPrHh7p5shuuNktv sv6hxHTLhiMKX893gxdT3XLS9OKmCv87vkINQcNEcIIoFWbP9HORz9v3vQwR4e3ksLc2JZOAFK+s sS5XMEoznzpihEP0PLc4dCBYjbvSD7kxgDwZ+Aj8Q9PkbvE9sIPP7ON0fz095HdThKjiVJe6vofq +n6b1NBc8XdrQvBmunwxD5nvtTW4vtN6VY7mUCmxsCieuoBJ9OlqmsVWQvifIYf40dJPZkk9YgGT zWLpXDSfLSplbY2LL9C9U0ptvjcDjefLTvqSFc7tw1sEhF0n/qpA2r0GpvkLRDmcSwVyPvmjFBGq Up/pNy8ZuPGQmHwFi2/14+xeSUDG2bwnsYJQG2EdJCB6luQ57GEnTA/yKZSTKI8dDQa8Sd3zfXb1 9mOgSF0bBdXbuKhEpuP9wirslFe6fQ1t5j5R0xi72MZ8ikMu1RQZKCyDbMwazlHiMIIHFzCCBf+g AwIBAgIDBCZ6MA0GCSqGSIb3DQEBBQUAMIGMMQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRD b20gTHRkLjErMCkGA1UECxMiU2VjdXJlIERpZ2l0YWwgQ2VydGlmaWNhdGUgU2lnbmluZzE4MDYG A1UEAxMvU3RhcnRDb20gQ2xhc3MgMSBQcmltYXJ5IEludGVybWVkaWF0ZSBDbGllbnQgQ0EwHhcN MTIwNTAxMTI1ODI3WhcNMTMwNTAzMTEzNzIwWjBdMRkwFwYDVQQNExA4Y1VOSzUzMTc0ODRYRjk3 MRwwGgYDVQQDDBNkd213MkBpbmZyYWRlYWQub3JnMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZy YWRlYWQub3JnMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAyYe7wo6MrtrB4uIGGbrY 4IifY/Xsq22pSv605yganL0+uyUdd8rCjrYlH6Q/ra5TVJCQFTgzaepkuqPQc79DC/Cxmzm6Qo+s wLZy868oFsccsVokL2bPAWIPaRXfNPJKkYR1FTWQfZpWJVQmT+sPf1XFUullVBAK+d9RztopyacI xWoZ/W/Cmv7mseQbttYTtGKJa0btX73nsQRWl6SgErWXo59zg9friCLTy1GXMXJYB8H+PtnuwX0w MrAvWDdX1ABgIlA17W3FraCn0eW15ZM46eyu0/amGzJZNtemCWF73P7BAijzeV1jNmiJFXdZ0DT0 w+hmtMO9PxdDUyt78QIDAQABo4IDrjCCA6owCQYDVR0TBAIwADALBgNVHQ8EBAMCBLAwHQYDVR0l BBYwFAYIKwYBBQUHAwIGCCsGAQUFBwMEMB0GA1UdDgQWBBTkfe5UOr3PcirsjApibyyUEfsyRzAf BgNVHSMEGDAWgBRTcu2SnODaywFcfH6WNU7y1LhRgjAeBgNVHREEFzAVgRNkd213MkBpbmZyYWRl YWQub3JnMIICIQYDVR0gBIICGDCCAhQwggIQBgsrBgEEAYG1NwECAjCCAf8wLgYIKwYBBQUHAgEW Imh0dHA6Ly93d3cuc3RhcnRzc2wuY29tL3BvbGljeS5wZGYwNAYIKwYBBQUHAgEWKGh0dHA6Ly93 d3cuc3RhcnRzc2wuY29tL2ludGVybWVkaWF0ZS5wZGYwgfcGCCsGAQUFBwICMIHqMCcWIFN0YXJ0 Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MAMCAQEagb5UaGlzIGNlcnRpZmljYXRlIHdhcyBp c3N1ZWQgYWNjb3JkaW5nIHRvIHRoZSBDbGFzcyAxIFZhbGlkYXRpb24gcmVxdWlyZW1lbnRzIG9m IHRoZSBTdGFydENvbSBDQSBwb2xpY3ksIHJlbGlhbmNlIG9ubHkgZm9yIHRoZSBpbnRlbmRlZCBw dXJwb3NlIGluIGNvbXBsaWFuY2Ugb2YgdGhlIHJlbHlpbmcgcGFydHkgb2JsaWdhdGlvbnMuMIGc BggrBgEFBQcCAjCBjzAnFiBTdGFydENvbSBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTADAgECGmRM aWFiaWxpdHkgYW5kIHdhcnJhbnRpZXMgYXJlIGxpbWl0ZWQhIFNlZSBzZWN0aW9uICJMZWdhbCBh bmQgTGltaXRhdGlvbnMiIG9mIHRoZSBTdGFydENvbSBDQSBwb2xpY3kuMDYGA1UdHwQvMC0wK6Ap oCeGJWh0dHA6Ly9jcmwuc3RhcnRzc2wuY29tL2NydHUxLWNybC5jcmwwgY4GCCsGAQUFBwEBBIGB MH8wOQYIKwYBBQUHMAGGLWh0dHA6Ly9vY3NwLnN0YXJ0c3NsLmNvbS9zdWIvY2xhc3MxL2NsaWVu dC9jYTBCBggrBgEFBQcwAoY2aHR0cDovL2FpYS5zdGFydHNzbC5jb20vY2VydHMvc3ViLmNsYXNz MS5jbGllbnQuY2EuY3J0MCMGA1UdEgQcMBqGGGh0dHA6Ly93d3cuc3RhcnRzc2wuY29tLzANBgkq hkiG9w0BAQUFAAOCAQEAqDU1FKifNtCFJbLnvOi1BLRfk7mut55PMtPSZLJ4/AnG7AjmJnbBI4U5 DELwvVq3mIpwUpGqZUkqkZMEfBPIbfq517UZB3h4iANtqif+ULfTLhg5XgcK5eF8/T6EtX2c3epq ylARdleCbj/0FwiUDvPlTsA6PIN4SCekjRLgjKERrL3heFz+Hteq1rtMAvMkNuyL0/0ijyyg2y45 NASAl2Afl9SLes/fnoh9nBwzfNQfb6qDYUFpnglfpGrq/0b1NtaOUb2z1SR+H1tKlb8bVJJIdvpu mEi27kSRIhzk3h30uTfKkKetgy++ouyldxZ7KZ0PuoLQrBy465EoQLosETCCBxcwggX/oAMCAQIC AwQmejANBgkqhkiG9w0BAQUFADCBjDELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0Q29tIEx0 ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcxODA2BgNVBAMT L1N0YXJ0Q29tIENsYXNzIDEgUHJpbWFyeSBJbnRlcm1lZGlhdGUgQ2xpZW50IENBMB4XDTEyMDUw MTEyNTgyN1oXDTEzMDUwMzExMzcyMFowXTEZMBcGA1UEDRMQOGNVTks1MzE3NDg0WEY5NzEcMBoG A1UEAwwTZHdtdzJAaW5mcmFkZWFkLm9yZzEiMCAGCSqGSIb3DQEJARYTZHdtdzJAaW5mcmFkZWFk Lm9yZzCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMmHu8KOjK7aweLiBhm62OCIn2P1 7KttqUr+tOcoGpy9PrslHXfKwo62JR+kP62uU1SQkBU4M2nqZLqj0HO/QwvwsZs5ukKPrMC2cvOv KBbHHLFaJC9mzwFiD2kV3zTySpGEdRU1kH2aViVUJk/rD39VxVLpZVQQCvnfUc7aKcmnCMVqGf1v wpr+5rHkG7bWE7RiiWtG7V+957EEVpekoBK1l6Ofc4PX64gi08tRlzFyWAfB/j7Z7sF9MDKwL1g3 V9QAYCJQNe1txa2gp9HlteWTOOnsrtP2phsyWTbXpglhe9z+wQIo83ldYzZoiRV3WdA09MPoZrTD vT8XQ1Mre/ECAwEAAaOCA64wggOqMAkGA1UdEwQCMAAwCwYDVR0PBAQDAgSwMB0GA1UdJQQWMBQG CCsGAQUFBwMCBggrBgEFBQcDBDAdBgNVHQ4EFgQU5H3uVDq9z3Iq7IwKYm8slBH7MkcwHwYDVR0j BBgwFoAUU3Ltkpzg2ssBXHx+ljVO8tS4UYIwHgYDVR0RBBcwFYETZHdtdzJAaW5mcmFkZWFkLm9y ZzCCAiEGA1UdIASCAhgwggIUMIICEAYLKwYBBAGBtTcBAgIwggH/MC4GCCsGAQUFBwIBFiJodHRw Oi8vd3d3LnN0YXJ0c3NsLmNvbS9wb2xpY3kucGRmMDQGCCsGAQUFBwIBFihodHRwOi8vd3d3LnN0 YXJ0c3NsLmNvbS9pbnRlcm1lZGlhdGUucGRmMIH3BggrBgEFBQcCAjCB6jAnFiBTdGFydENvbSBD ZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTADAgEBGoG+VGhpcyBjZXJ0aWZpY2F0ZSB3YXMgaXNzdWVk IGFjY29yZGluZyB0byB0aGUgQ2xhc3MgMSBWYWxpZGF0aW9uIHJlcXVpcmVtZW50cyBvZiB0aGUg U3RhcnRDb20gQ0EgcG9saWN5LCByZWxpYW5jZSBvbmx5IGZvciB0aGUgaW50ZW5kZWQgcHVycG9z ZSBpbiBjb21wbGlhbmNlIG9mIHRoZSByZWx5aW5nIHBhcnR5IG9ibGlnYXRpb25zLjCBnAYIKwYB BQUHAgIwgY8wJxYgU3RhcnRDb20gQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkwAwIBAhpkTGlhYmls aXR5IGFuZCB3YXJyYW50aWVzIGFyZSBsaW1pdGVkISBTZWUgc2VjdGlvbiAiTGVnYWwgYW5kIExp bWl0YXRpb25zIiBvZiB0aGUgU3RhcnRDb20gQ0EgcG9saWN5LjA2BgNVHR8ELzAtMCugKaAnhiVo dHRwOi8vY3JsLnN0YXJ0c3NsLmNvbS9jcnR1MS1jcmwuY3JsMIGOBggrBgEFBQcBAQSBgTB/MDkG CCsGAQUFBzABhi1odHRwOi8vb2NzcC5zdGFydHNzbC5jb20vc3ViL2NsYXNzMS9jbGllbnQvY2Ew QgYIKwYBBQUHMAKGNmh0dHA6Ly9haWEuc3RhcnRzc2wuY29tL2NlcnRzL3N1Yi5jbGFzczEuY2xp ZW50LmNhLmNydDAjBgNVHRIEHDAahhhodHRwOi8vd3d3LnN0YXJ0c3NsLmNvbS8wDQYJKoZIhvcN AQEFBQADggEBAKg1NRSonzbQhSWy57zotQS0X5O5rreeTzLT0mSyePwJxuwI5iZ2wSOFOQxC8L1a t5iKcFKRqmVJKpGTBHwTyG36ude1GQd4eIgDbaon/lC30y4YOV4HCuXhfP0+hLV9nN3qaspQEXZX gm4/9BcIlA7z5U7AOjyDeEgnpI0S4IyhEay94Xhc/h7Xqta7TALzJDbsi9P9Io8soNsuOTQEgJdg H5fUi3rP356IfZwcM3zUH2+qg2FBaZ4JX6Rq6v9G9TbWjlG9s9Ukfh9bSpW/G1SSSHb6bphItu5E kSIc5N4d9Lk3ypCnrYMvvqLspXcWeymdD7qC0KwcuOuRKEC6LBExggNvMIIDawIBATCBlDCBjDEL MAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdp dGFsIENlcnRpZmljYXRlIFNpZ25pbmcxODA2BgNVBAMTL1N0YXJ0Q29tIENsYXNzIDEgUHJpbWFy eSBJbnRlcm1lZGlhdGUgQ2xpZW50IENBAgMEJnowCQYFKw4DAhoFAKCCAa8wGAYJKoZIhvcNAQkD MQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTIxMTI4MTAxOTIwWjAjBgkqhkiG9w0BCQQx FgQU2svXW1UrKZ0Ixpw79CVkD9JT6NcwgaUGCSsGAQQBgjcQBDGBlzCBlDCBjDELMAkGA1UEBhMC SUwxFjAUBgNVBAoTDVN0YXJ0Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRp ZmljYXRlIFNpZ25pbmcxODA2BgNVBAMTL1N0YXJ0Q29tIENsYXNzIDEgUHJpbWFyeSBJbnRlcm1l ZGlhdGUgQ2xpZW50IENBAgMEJnowgacGCyqGSIb3DQEJEAILMYGXoIGUMIGMMQswCQYDVQQGEwJJ TDEWMBQGA1UEChMNU3RhcnRDb20gTHRkLjErMCkGA1UECxMiU2VjdXJlIERpZ2l0YWwgQ2VydGlm aWNhdGUgU2lnbmluZzE4MDYGA1UEAxMvU3RhcnRDb20gQ2xhc3MgMSBQcmltYXJ5IEludGVybWVk aWF0ZSBDbGllbnQgQ0ECAwQmejANBgkqhkiG9w0BAQEFAASCAQBzQlMsg4FlM4MR+R3bDrJQCtx3 2OIzJTVo+11wDrGyp+upg5jAU1nNNQ54ubFftzPLmrhN+DYDYCVnbKcdbypAWrC6leB01H7gYwUg W98ZBsmTuF+zhctnWrkWKCikUlrLzu8Y9UKARPLjmRv4BC7FREdGxT6IO3zCg//DDdiaFemuPqDF vKYu34Wkig/R211dz2jOR9vWbwKDVp7lxOZHlujSZh3y66nhkxGu5tNyUtYWVAVofYx6UHcCuwqV oYm1e9r8yuy1pggvJ2VMQB1wU8luG8Hhloj9HYu04X8hH18/9RZYME3KEi9rGJstE6U2VQG/K66S vqqUzkqiRMttAAAAAAAA --=-VyX/Gs/GPavwzdwUwmHr-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/