From nobody Sat Apr 11 12:47:19 2026 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 C000EC25B0C for ; Thu, 11 Aug 2022 09:43:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234988AbiHKJn1 (ORCPT ); Thu, 11 Aug 2022 05:43:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234999AbiHKJnU (ORCPT ); Thu, 11 Aug 2022 05:43:20 -0400 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F0FB81686 for ; Thu, 11 Aug 2022 02:43:17 -0700 (PDT) Received: by mail-pl1-x62a.google.com with SMTP id y1so10881611plb.2 for ; Thu, 11 Aug 2022 02:43:17 -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; bh=k56CFyy5q/tLEdDa0AaNeHTf8E8dmcjqwpdigPl2beI=; b=nYhxQ7ANk4AWRoCB8jzIH9ZSlpstq2dnKXa/l6fhzvMZMZDTwkFHFBixe1fIqQ85vO iPECz1eMOMgDFVgb/2saEnVkaOwv4Qazm4qE0kaOpkbkfxeIRdUMQaLgfkn/gs9tLqyU DNIqKF0xH4Sz42q3L2h0/sd3NBT0BG8WalPZKvCC/1/PwJjKNgJOF+oHtYc9HI+rrvrT L/JU35VXhDy/vvvQS5uqs9INRQw791vA3sSKNoQB9zhZuGr07tDCYp/8HqZkjoSl2k+0 0eAsUG3yy5c75sAlTrbCb1HwT2AkHvESOuG4o3V94NZ+zTvxhGv2aFFzDjz03yfX+zFM siUw== 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; bh=k56CFyy5q/tLEdDa0AaNeHTf8E8dmcjqwpdigPl2beI=; b=HQsFxRUOjeWG+2tmTd5+RsjagFjp4Iwb6n4B0iz+8t2IJLFoMy75j2KRn80o4Kico+ QswkusI+ZHFo0urzScc1tMTQPT5ygDz1i8wWO9i0RFRuDhmnQ+SyvRItY9CfzQ5HejXQ KohJB6T1Hagx4H/vKI1rlEMZBBJmjDbpvB8PDyDL3BFSu6c91CCH2BlQ+F1rSF4Dv+/0 SLqB6kuEb53ax5zHsBrAijDRUdvaK3q9GT1cg8DcNfnS/lI+LCZuERm5aKMuN/tqzdSk f4jkBHcmRDwDPp0KgM82x7Te9S6fzrZyoh044dCW2i5yUJutdCHNoLgvgxb0I3qScypl HfeA== X-Gm-Message-State: ACgBeo22NkikmYr20AUOiw2myxP1J+rAOKyoV1OKSomffc0krIQdHGBc ljXXZpdQWEJfOPgrrFCzh2/F X-Google-Smtp-Source: AA6agR5tKVwsjMFBxrIELk3vEUMRLTH0iKIhFw/yTCr20+HlexLLyHVtt89b63geJ1+8Es3yXKKT2w== X-Received: by 2002:a17:90a:d789:b0:1f5:1c76:24d6 with SMTP id z9-20020a17090ad78900b001f51c7624d6mr7942691pju.188.1660210996830; Thu, 11 Aug 2022 02:43:16 -0700 (PDT) Received: from localhost.localdomain ([59.92.103.103]) by smtp.gmail.com with ESMTPSA id s5-20020a625e05000000b0052e6d5ee183sm3553931pfb.129.2022.08.11.02.43.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Aug 2022 02:43:16 -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 1/2] PCI: endpoint: Use callback mechanism for passing events from EPC to EPF Date: Thu, 11 Aug 2022 15:12:36 +0530 Message-Id: <20220811094237.77632-2-manivannan.sadhasivam@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220811094237.77632-1-manivannan.sadhasivam@linaro.org> References: <20220811094237.77632-1-manivannan.sadhasivam@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 | 7 ++++++- include/linux/pci-epf.h | 11 ++++++++++- 3 files changed, 22 insertions(+), 9 deletions(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/en= dpoint/functions/pci-epf-test.c index d917a9d2be09..069943b57029 100644 --- a/drivers/pci/endpoint/functions/pci-epf-test.c +++ b/drivers/pci/endpoint/functions/pci-epf-test.c @@ -731,20 +731,17 @@ static int pci_epf_test_core_init(struct pci_epf *epf) return 0; } =20 +static const struct pci_epc_event_ops pci_epf_test_event_ops =3D { + .core_init =3D pci_epf_test_core_init, +}; + static int pci_epf_test_notifier(struct notifier_block *nb, unsigned long = val, void *data) { struct pci_epf *epf =3D container_of(nb, struct pci_epf, nb); struct pci_epf_test *epf_test =3D epf_get_drvdata(epf); - int ret; =20 switch (val) { - case CORE_INIT: - ret =3D 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)); @@ -915,6 +912,8 @@ static int pci_epf_test_probe(struct pci_epf *epf, cons= t struct pci_epf_device_i =20 INIT_DELAYED_WORK(&epf_test->cmd_handler, pci_epf_test_cmd_handler); =20 + epf->event_ops =3D &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 3bc9273d0a08..805f3d64f93b 100644 --- a/drivers/pci/endpoint/pci-epc-core.c +++ b/drivers/pci/endpoint/pci-epc-core.c @@ -707,10 +707,15 @@ 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; =20 - atomic_notifier_call_chain(&epc->notifier, CORE_INIT, NULL); + list_for_each_entry(epf, &epc->pci_epf, list) { + if (epf->event_ops->core_init) + epf->event_ops->core_init(epf); + } } EXPORT_SYMBOL_GPL(pci_epc_init_notify); =20 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; =20 enum pci_notify_event { - CORE_INIT, LINK_UP, }; =20 @@ -72,6 +71,14 @@ struct pci_epf_ops { struct config_group *group); }; =20 +/** + * 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 func= tion + * @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; }; =20 /** --=20 2.25.1 From nobody Sat Apr 11 12:47:19 2026 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 B9A15C19F2A for ; Thu, 11 Aug 2022 09:43:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234253AbiHKJnh (ORCPT ); Thu, 11 Aug 2022 05:43:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234138AbiHKJnW (ORCPT ); Thu, 11 Aug 2022 05:43:22 -0400 Received: from mail-pj1-x1032.google.com (mail-pj1-x1032.google.com [IPv6:2607:f8b0:4864:20::1032]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 457A181697 for ; 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charset="utf-8" As a part of the transition towards callback mechanism for signalling the events from EPC to EPF, let's use the link_up() callback in the place of the LINK_UP notifier. This also removes the notifier support completely from the PCI endpoint framework. Signed-off-by: Manivannan Sadhasivam --- drivers/pci/endpoint/functions/pci-epf-test.c | 33 ++++++------------- drivers/pci/endpoint/pci-epc-core.c | 8 +++-- include/linux/pci-epc.h | 8 ----- include/linux/pci-epf.h | 8 ++--- 4 files changed, 18 insertions(+), 39 deletions(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/en= dpoint/functions/pci-epf-test.c index 069943b57029..37454538c000 100644 --- a/drivers/pci/endpoint/functions/pci-epf-test.c +++ b/drivers/pci/endpoint/functions/pci-epf-test.c @@ -731,30 +731,21 @@ static int pci_epf_test_core_init(struct pci_epf *epf) return 0; } =20 -static const struct pci_epc_event_ops pci_epf_test_event_ops =3D { - .core_init =3D pci_epf_test_core_init, -}; - -static int pci_epf_test_notifier(struct notifier_block *nb, unsigned long = val, - void *data) +int pci_epf_test_link_up(struct pci_epf *epf) { - struct pci_epf *epf =3D container_of(nb, struct pci_epf, nb); struct pci_epf_test *epf_test =3D epf_get_drvdata(epf); =20 - switch (val) { - case LINK_UP: - queue_delayed_work(kpcitest_workqueue, &epf_test->cmd_handler, - msecs_to_jiffies(1)); - break; - - default: - dev_err(&epf->dev, "Invalid EPF test notifier event\n"); - return NOTIFY_BAD; - } + queue_delayed_work(kpcitest_workqueue, &epf_test->cmd_handler, + msecs_to_jiffies(1)); =20 - return NOTIFY_OK; + return 0; } =20 +static const struct pci_epc_event_ops pci_epf_test_event_ops =3D { + .core_init =3D pci_epf_test_core_init, + .link_up =3D pci_epf_test_link_up, +}; + static int pci_epf_test_alloc_space(struct pci_epf *epf) { struct pci_epf_test *epf_test =3D epf_get_drvdata(epf); @@ -881,12 +872,8 @@ static int pci_epf_test_bind(struct pci_epf *epf) if (ret) epf_test->dma_supported =3D false; =20 - if (linkup_notifier || core_init_notifier) { - epf->nb.notifier_call =3D pci_epf_test_notifier; - pci_epc_register_notifier(epc, &epf->nb); - } else { + if (!linkup_notifier && !core_init_notifier) queue_work(kpcitest_workqueue, &epf_test->cmd_handler.work); - } =20 return 0; } diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci= -epc-core.c index 805f3d64f93b..a51ba9f158c3 100644 --- a/drivers/pci/endpoint/pci-epc-core.c +++ b/drivers/pci/endpoint/pci-epc-core.c @@ -690,10 +690,15 @@ EXPORT_SYMBOL_GPL(pci_epc_remove_epf); */ void pci_epc_linkup(struct pci_epc *epc) { + struct pci_epf *epf; + if (!epc || IS_ERR(epc)) return; =20 - atomic_notifier_call_chain(&epc->notifier, LINK_UP, NULL); + list_for_each_entry(epf, &epc->pci_epf, list) { + if (epf->event_ops->link_up) + epf->event_ops->link_up(epf); + } } EXPORT_SYMBOL_GPL(pci_epc_linkup); =20 @@ -779,7 +784,6 @@ __pci_epc_create(struct device *dev, const struct pci_e= pc_ops *ops, =20 mutex_init(&epc->lock); INIT_LIST_HEAD(&epc->pci_epf); - ATOMIC_INIT_NOTIFIER_HEAD(&epc->notifier); =20 device_initialize(&epc->dev); epc->dev.class =3D pci_epc_class; diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h index a48778e1a4ee..05604fe0ede0 100644 --- a/include/linux/pci-epc.h +++ b/include/linux/pci-epc.h @@ -134,7 +134,6 @@ struct pci_epc_mem { * @group: configfs group representing the PCI EPC device * @lock: mutex to protect pci_epc ops * @function_num_map: bitmap to manage physical function number - * @notifier: used to notify EPF of any EPC events (like linkup) */ struct pci_epc { struct device dev; @@ -149,7 +148,6 @@ struct pci_epc { /* mutex to protect against concurrent access of EP controller */ struct mutex lock; unsigned long function_num_map; - struct atomic_notifier_head notifier; }; =20 /** @@ -192,12 +190,6 @@ static inline void *epc_get_drvdata(struct pci_epc *ep= c) return dev_get_drvdata(&epc->dev); } =20 -static inline int -pci_epc_register_notifier(struct pci_epc *epc, struct notifier_block *nb) -{ - return atomic_notifier_chain_register(&epc->notifier, nb); -} - struct pci_epc * __devm_pci_epc_create(struct device *dev, const struct pci_epc_ops *ops, struct module *owner); diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h index a06f3b4c8bee..bc613f0df7e3 100644 --- a/include/linux/pci-epf.h +++ b/include/linux/pci-epf.h @@ -17,10 +17,6 @@ struct pci_epf; enum pci_epc_interface_type; =20 -enum pci_notify_event { - LINK_UP, -}; - enum pci_barno { NO_BAR =3D -1, BAR_0, @@ -74,9 +70,11 @@ struct pci_epf_ops { /** * struct pci_epf_event_ops - Callbacks for capturing the EPC events * @core_init: Callback for the EPC initialization complete event + * @link_up: Callback for the EPC link up event */ struct pci_epc_event_ops { int (*core_init)(struct pci_epf *epf); + int (*link_up)(struct pci_epf *epf); }; =20 /** @@ -135,7 +133,6 @@ struct pci_epf_bar { * @driver: the EPF driver to which this EPF device is bound * @id: Pointer to the EPF device ID * @list: to add pci_epf as a list of PCI endpoint functions to pci_epc - * @nb: notifier block to notify EPF of any EPC events (like linkup) * @lock: mutex to protect pci_epf_ops * @sec_epc: the secondary EPC device to which this EPF device is bound * @sec_epc_list: to add pci_epf as list of PCI endpoint functions to seco= ndary @@ -164,7 +161,6 @@ struct pci_epf { struct pci_epf_driver *driver; const struct pci_epf_device_id *id; struct list_head list; - struct notifier_block nb; /* mutex to protect against concurrent access of pci_epf_ops */ struct mutex lock; =20 --=20 2.25.1