From patchwork Sat Sep 10 09:05:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Manivannan Sadhasivam X-Patchwork-Id: 12972469 X-Patchwork-Delegate: lorenzo.pieralisi@arm.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 521F0ECAAD5 for ; Sat, 10 Sep 2022 09:05:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229615AbiIJJFp (ORCPT ); Sat, 10 Sep 2022 05:05:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229604AbiIJJFm (ORCPT ); Sat, 10 Sep 2022 05:05:42 -0400 Received: from mail-wm1-x334.google.com (mail-wm1-x334.google.com [IPv6:2a00:1450:4864:20::334]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3C7A5E55E for ; Sat, 10 Sep 2022 02:05:34 -0700 (PDT) Received: by mail-wm1-x334.google.com with SMTP id h1so3434432wmd.3 for ; Sat, 10 Sep 2022 02:05:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=b98/tdiTwcvqr19Hh3b2b2FTs+schd1Q4q9W1vv+i7w=; b=ohJS3hlCgdsZHY3kYb3U5BKU2/re/UNPkN9oF6OlLGO8sqrImlo8onawrAwuQhqnjK hjPX8ycYVFwYyY0uXf5KAOkfL5FE+5oiw7AwDe0vuR7OsdAltEtS+tq2d1vWpjbNJSZW k68fQ8hL3lJcA5mTpLH/0lSlfA+21eFkoTOlzF1Dn8zyNpNm9zI4qEinxg0Q3DvlAYHw DurNCNO/Tw6mngJtG4K1PEM5UYgkXfhDeys1Ttr61fghb6wACmKw2mnT1PKNJ5D09LXj ZGQlRYCXNoDPdi6LkLwFM6DJZqBmCZXuPi+1w37U5fk8CntzcFH6dUxpv/6DxwQ4xWhd q8WA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=b98/tdiTwcvqr19Hh3b2b2FTs+schd1Q4q9W1vv+i7w=; b=5CgPeNhGhvPiTetxWf4TlKdO73Dqc0ADDC4rSPoFCKD7Cag/7DtNig5ZdB1Cl908pw 1tCv8ocnWk8v/DzjSC/MkGbfZLqTv6NSPGwwZf9j/GJMopVDKAaSu4T6VUE2UNoQ9sb0 jhh6Ucb7LX2/mF+d0vCZbUHD5MTvZHe83+uqGqNkquzCL/tPRzkRCIHsYCkA1Pwo5sux pq0LxN/Lh7ZQFx+pBriv8d/OH7spXRBkXIS59GoAjLRtXOq9P2O9Pyh1buw3K+T5ARVZ 502QNAwlG80+W2x1uu/ayaSH7+3SwTBOCJLk1V2vm4QNCyvG7STiDjleqYesy9ZGb/R5 uTzw== X-Gm-Message-State: ACgBeo0vl6R1p0j9hMBlqAsaBT7IZvahOjXnmIVFg3tsY/uiGZG7ye/+ 01HdE91smj72lWzMQ3pm5m6q X-Google-Smtp-Source: AA6agR4VCabiqZGHOihA6XufU8f13OMt9bFL0OCiGQoZ5lBepE/P6lsxg8w4Q38HSGAyDXQ2uFUnPg== X-Received: by 2002:a05:600c:5028:b0:3a8:4349:153c with SMTP id n40-20020a05600c502800b003a84349153cmr7870930wmr.130.1662800733313; Sat, 10 Sep 2022 02:05:33 -0700 (PDT) Received: from localhost.localdomain ([117.217.182.47]) by smtp.gmail.com with ESMTPSA id i81-20020a1c3b54000000b003a8418ee646sm3081677wma.12.2022.09.10.02.05.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 10 Sep 2022 02:05:32 -0700 (PDT) From: Manivannan Sadhasivam To: kishon@ti.com, lpieralisi@kernel.org, bhelgaas@google.com Cc: kw@linux.com, robh@kernel.org, vidyas@nvidia.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Manivannan Sadhasivam Subject: [PATCH v2 2/3] PCI: endpoint: Use callback mechanism for passing events from EPC to EPF Date: Sat, 10 Sep 2022 14:35:07 +0530 Message-Id: <20220910090508.61157-3-manivannan.sadhasivam@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220910090508.61157-1-manivannan.sadhasivam@linaro.org> References: <20220910090508.61157-1-manivannan.sadhasivam@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Instead of using the notifiers for passing the events from EPC to EPF, let's introduce a callback based mechanism where the EPF drivers can populate relevant callbacks for EPC events they want to subscribe. The use of notifiers in kernel is not recommended if there is a real link between the sender and receiver, like in this case. Also, the existing atomic notifier forces the notification functions to be in atomic context while the caller may be in non-atomic context. For instance, the two in-kernel users of the notifiers, pcie-qcom and pcie-tegra194, both are calling the notifier functions in non-atomic context (from threaded IRQ handlers). This creates a sleeping in atomic context issue with the existing EPF_TEST driver that calls the EPC APIs that may sleep. For all these reasons, let's get rid of the notifier chains and use the simple callback mechanism for signalling the events from EPC to EPF drivers. This preserves the context of the caller and avoids the latency of going through a separate interface for triggering the notifications. As a first step of the transition, the core_init() callback is introduced in this commit, that'll replace the existing CORE_INIT notifier used for signalling the init complete event from EPC. During the occurrence of the event, EPC will go over the list of EPF drivers attached to it and will call the core_init() callback if available. Signed-off-by: Manivannan Sadhasivam --- drivers/pci/endpoint/functions/pci-epf-test.c | 13 ++++++------- drivers/pci/endpoint/pci-epc-core.c | 11 ++++++++++- include/linux/pci-epf.h | 11 ++++++++++- 3 files changed, 26 insertions(+), 9 deletions(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c index a6f906a96669..868de17e1ad2 100644 --- a/drivers/pci/endpoint/functions/pci-epf-test.c +++ b/drivers/pci/endpoint/functions/pci-epf-test.c @@ -826,20 +826,17 @@ static int pci_epf_test_core_init(struct pci_epf *epf) return 0; } +static const struct pci_epc_event_ops pci_epf_test_event_ops = { + .core_init = pci_epf_test_core_init, +}; + static int pci_epf_test_notifier(struct notifier_block *nb, unsigned long val, void *data) { struct pci_epf *epf = container_of(nb, struct pci_epf, nb); struct pci_epf_test *epf_test = epf_get_drvdata(epf); - int ret; switch (val) { - case CORE_INIT: - ret = pci_epf_test_core_init(epf); - if (ret) - return NOTIFY_BAD; - break; - case LINK_UP: queue_delayed_work(kpcitest_workqueue, &epf_test->cmd_handler, msecs_to_jiffies(1)); @@ -1010,6 +1007,8 @@ static int pci_epf_test_probe(struct pci_epf *epf, const struct pci_epf_device_i INIT_DELAYED_WORK(&epf_test->cmd_handler, pci_epf_test_cmd_handler); + epf->event_ops = &pci_epf_test_event_ops; + epf_set_drvdata(epf, epf_test); return 0; } diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c index 6cce430d431b..ba54f17ae06f 100644 --- a/drivers/pci/endpoint/pci-epc-core.c +++ b/drivers/pci/endpoint/pci-epc-core.c @@ -707,10 +707,19 @@ EXPORT_SYMBOL_GPL(pci_epc_linkup); */ void pci_epc_init_notify(struct pci_epc *epc) { + struct pci_epf *epf; + if (!epc || IS_ERR(epc)) return; - atomic_notifier_call_chain(&epc->notifier, CORE_INIT, NULL); + mutex_lock(&epc->list_lock); + list_for_each_entry(epf, &epc->pci_epf, list) { + mutex_lock(&epf->lock); + if (epf->event_ops->core_init) + epf->event_ops->core_init(epf); + mutex_unlock(&epf->lock); + } + mutex_unlock(&epc->list_lock); } EXPORT_SYMBOL_GPL(pci_epc_init_notify); diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h index 0c94cc1513bc..a06f3b4c8bee 100644 --- a/include/linux/pci-epf.h +++ b/include/linux/pci-epf.h @@ -18,7 +18,6 @@ struct pci_epf; enum pci_epc_interface_type; enum pci_notify_event { - CORE_INIT, LINK_UP, }; @@ -72,6 +71,14 @@ struct pci_epf_ops { struct config_group *group); }; +/** + * struct pci_epf_event_ops - Callbacks for capturing the EPC events + * @core_init: Callback for the EPC initialization complete event + */ +struct pci_epc_event_ops { + int (*core_init)(struct pci_epf *epf); +}; + /** * struct pci_epf_driver - represents the PCI EPF driver * @probe: ops to perform when a new EPF device has been bound to the EPF driver @@ -140,6 +147,7 @@ struct pci_epf_bar { * @is_vf: true - virtual function, false - physical function * @vfunction_num_map: bitmap to manage virtual function number * @pci_vepf: list of virtual endpoint functions associated with this function + * @event_ops: Callbacks for capturing the EPC events */ struct pci_epf { struct device dev; @@ -170,6 +178,7 @@ struct pci_epf { unsigned int is_vf; unsigned long vfunction_num_map; struct list_head pci_vepf; + const struct pci_epc_event_ops *event_ops; }; /**