From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: ACJfBosVVvrJxnrxkxwqTTZm/8oxb7FmH4anD0OYJGazpm/K9fXwPTZuyVJ6nrBvJoK+9DKXWasx ARC-Seal: i=1; a=rsa-sha256; t=1516293004; cv=none; d=google.com; s=arc-20160816; b=Ey2/Ftnr8CdOtrqiDTT+/Hol5iJdAjcgKksC7nW5MupOfmOpaL6EkBx8o6dNVB1T1Y GF1ppgC6VjguSnuIPdZzQ3OABs24CNCEF05h+yDxWCUSItmci7gcFpqIgZpH7oFKZ2ih CX5XWY0rnKu6QVoWVbvaD7xtln+1BlOhlYdcvUVYcz3hjlvS/6/szQNXSA58EHOkHiVL hPvcDeT9Cv71ERGId8RHS6ZLJP+wIAA2ceRQFNkO1Rg1a9HhKEMg85UKPX2+DSdeiOyM TC5DkwG151vJaByQ9rqqBCgvqoMQNQBwjjycs1e4R2BUnN9VcJ9E1DH8At1784doQCxO EaJQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=nDEybxaRgPSgML2k7ezO5U1nIaF8nuTpXWovZBE9aIM=; b=a0Hm4YebVGcqppRq+NYba+u79tsj0LLCoB2XYc+rKkcrZoiUO5JcG/szpoNk65kWQQ VBSr7oBoxIHni0VSIJ39s1cFWLZe8hs96AnweLMUo0/cIRcdnI1t/bs8bZvIHTL40ri3 orHRfo/oXMTCJNKGdxDx297vxgpVKGKRmdS/Kif4y4HPc5cpb9gKGPkOEMwz6cwC1LM5 fhmzxUuXwAq+WEKOikpjL8Stwr9YT15XVFhAd3Frp7uvBr3CAPEZm+C/KLy8qsiU7GSS 4ZSBZTRQaaDVCGHD1zYX5Lv0hVtOsJJRr0RrDkmkC1h/sJmG1Pw8XtumM7q5fOZem03h VIaQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=uo3y4klq; spf=pass (google.com: best guess record for domain of batv+8aa4359751633f819e66+5261+infradead.org+hch@bombadil.srs.infradead.org designates 65.50.211.133 as permitted sender) smtp.mailfrom=BATV+8aa4359751633f819e66+5261+infradead.org+hch@bombadil.srs.infradead.org Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=uo3y4klq; spf=pass (google.com: best guess record for domain of batv+8aa4359751633f819e66+5261+infradead.org+hch@bombadil.srs.infradead.org designates 65.50.211.133 as permitted sender) smtp.mailfrom=BATV+8aa4359751633f819e66+5261+infradead.org+hch@bombadil.srs.infradead.org Date: Thu, 18 Jan 2018 08:29:57 -0800 From: Christoph Hellwig To: Al Viro Cc: Linus Torvalds , Network Development , Dan Williams , Linux Kernel Mailing List , linux-arch@vger.kernel.org, Andi Kleen , Kees Cook , kernel-hardening@lists.openwall.com, Greg Kroah-Hartman , the arch/x86 maintainers , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Andrew Morton , Alan Cox , David Miller Subject: Re: [RFC][PATCH] get rid of the use of set_fs() (by way of kernel_recvmsg()) in sunrpc Message-ID: <20180118162957.GA16649@infradead.org> References: <1516198646.4184.13.camel@linux.intel.com> <20180117185232.GW13338@ZenIV.linux.org.uk> <20180118030634.GY13338@ZenIV.linux.org.uk> <20180118044302.GZ13338@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180118044302.GZ13338@ZenIV.linux.org.uk> User-Agent: Mutt/1.9.1 (2017-09-22) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1589897919168956864?= X-GMAIL-MSGID: =?utf-8?q?1589948451226962913?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: > We could turn ->msg_control/->msg_controllen into another > iov_iter, but seeing that we never do scatter-gather for those > IMO that would be a massive overkill. A flag controlling whether > ->msg_control is kernel or userland pointer would do, especially > since we already have a flag for "do we want a native or compat > layout for cmsg" in there. While your current hack seems like a nice short term improvement I think we need an iov_iter or iov_iter-light there in the long run. Same for ioctl so that we can pass properly typed kernel or user buffers through without all these set_fs hacks.