From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933123AbdIXUle (ORCPT ); Sun, 24 Sep 2017 16:41:34 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60548 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932776AbdIXUla (ORCPT ); Sun, 24 Sep 2017 16:41:30 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Frederic Barrat , Andrew Donnellan , Michael Ellerman Subject: [PATCH 4.13 040/109] cxl: Fix driver use count Date: Sun, 24 Sep 2017 22:33:01 +0200 Message-Id: <20170924203354.706309719@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170924203353.104695385@linuxfoundation.org> References: <20170924203353.104695385@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Frederic Barrat commit 197267d0356004a31c4d6b6336598f5dff3301e1 upstream. cxl keeps a driver use count, which is used with the hash memory model on p8 to know when to upgrade local TLBIs to global and to trigger callbacks to manage the MMU for PSL8. If a process opens a context and closes without attaching or fails the attachment, the driver use count is never decremented. As a consequence, TLB invalidations remain global, even if there are no active cxl contexts. We should increment the driver use count when the process is attaching to the cxl adapter, and not on open. It's not needed before the adapter starts using the context and the use count is decremented on the detach path, so it makes more sense. It affects only the user api. The kernel api is already doing The Right Thing. Signed-off-by: Frederic Barrat Fixes: 7bb5d91a4dda ("cxl: Rework context lifetimes") Acked-by: Andrew Donnellan Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- drivers/misc/cxl/api.c | 4 ++++ drivers/misc/cxl/file.c | 8 +++++++- 2 files changed, 11 insertions(+), 1 deletion(-) --- a/drivers/misc/cxl/api.c +++ b/drivers/misc/cxl/api.c @@ -336,6 +336,10 @@ int cxl_start_context(struct cxl_context mmput(ctx->mm); } + /* + * Increment driver use count. Enables global TLBIs for hash + * and callbacks to handle the segment table + */ cxl_ctx_get(); if ((rc = cxl_ops->attach_process(ctx, kernel, wed, 0))) { --- a/drivers/misc/cxl/file.c +++ b/drivers/misc/cxl/file.c @@ -95,7 +95,6 @@ static int __afu_open(struct inode *inod pr_devel("afu_open pe: %i\n", ctx->pe); file->private_data = ctx; - cxl_ctx_get(); /* indicate success */ rc = 0; @@ -225,6 +224,12 @@ static long afu_ioctl_start_work(struct if (ctx->mm) mmput(ctx->mm); + /* + * Increment driver use count. Enables global TLBIs for hash + * and callbacks to handle the segment table + */ + cxl_ctx_get(); + trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr); if ((rc = cxl_ops->attach_process(ctx, false, work.work_element_descriptor, @@ -233,6 +238,7 @@ static long afu_ioctl_start_work(struct cxl_adapter_context_put(ctx->afu->adapter); put_pid(ctx->pid); ctx->pid = NULL; + cxl_ctx_put(); cxl_context_mm_count_put(ctx); goto out; }