From patchwork Thu Jun 1 13:51:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ricardo Ribalda X-Patchwork-Id: 689007 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 52DE4C7EE23 for ; Thu, 1 Jun 2023 13:51:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233353AbjFANvw (ORCPT ); Thu, 1 Jun 2023 09:51:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233357AbjFANvq (ORCPT ); Thu, 1 Jun 2023 09:51:46 -0400 Received: from mail-ej1-x633.google.com (mail-ej1-x633.google.com [IPv6:2a00:1450:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FDAF192 for ; Thu, 1 Jun 2023 06:51:43 -0700 (PDT) Received: by mail-ej1-x633.google.com with SMTP id a640c23a62f3a-96f6e83e12fso118749066b.1 for ; Thu, 01 Jun 2023 06:51:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1685627502; x=1688219502; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:from:to:cc:subject:date:message-id:reply-to; bh=vVJTPL6ZF8NSM8+tIg6PCSL4IQNlSnliH+EHXpj1AeI=; b=LfZwL0vJanrn5T/tPKzxBB9HGeVBD2tFqokk0cShsaOJs6RAKryt+yzcXH/OpoVibO JT06DWXd+ftmoLPXsD9V0gKlsZxXNeOylQ+6npzjPCxyhvXxJmnwZXC7d0i7WkdTWaXJ 1o0jDjlmXV0mw/wlbFRYgfFOYyHPWrE7rAb7U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685627502; x=1688219502; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=vVJTPL6ZF8NSM8+tIg6PCSL4IQNlSnliH+EHXpj1AeI=; b=jrzsN7Ck8KAa11uWs0Wvix+fQRVoU5sz/Ag4xzlyHC8BEaU0v4H8HU7zkJQfGKEJXk ZXATZxE2EGin7GMomcrOXg0e4HjpiAQvocoxof3TpcjkkW/hhkS+uHXv3G7KLApULVFt lgqpdRcKvQG6yvfc3FFl1KMEu2kQ2HrZMY4quP1Vucvv7eAPl8tDPWdgWAqdSKTRsijL KKespD7Mu+Nx6EN83g1+nlovBxoyykC1pUdERYETTMsURBbvzVZ6T2H0WLad8mogJ4XT BiDYCXv9zp4Wa/p9OBgT51zakmTUV14UhSq8wxXxjCU7Gt3G8cDmisaveD1rhV5cTyVv RbdA== X-Gm-Message-State: AC+VfDygpeQGkUpNFXk3UsskSIsppyJh69O244PWxr67W+JQMSVhEKrs zZ50RZL2238otmdmZvE+IK2w4Q== X-Google-Smtp-Source: ACHHUZ6zSD+zjod6ePN4avGcolX6I1MjbMb4h5ISXrs0XfBu4df95UYKMPkiSvAw/zA/66OobrP2Iw== X-Received: by 2002:a17:907:3f97:b0:94f:6058:4983 with SMTP id hr23-20020a1709073f9700b0094f60584983mr8192612ejc.76.1685627502003; Thu, 01 Jun 2023 06:51:42 -0700 (PDT) Received: from alco.roam.corp.google.com ([2620:0:1059:10:8745:5c87:abd8:3631]) by smtp.gmail.com with ESMTPSA id f7-20020a170906494700b0095807ab4b57sm10795556ejt.178.2023.06.01.06.51.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Jun 2023 06:51:41 -0700 (PDT) From: Ricardo Ribalda Delgado Date: Thu, 01 Jun 2023 15:51:19 +0200 Subject: [PATCH v2] xhci: Do not create endpoint debugfs while holding the bandwidth mutex MIME-Version: 1.0 Message-Id: <20230531-xhci-deadlock-v2-1-5f5cf8ff5285@chromium.org> X-B4-Tracking: v=1; b=H4sIAFaieGQC/3WNwQ6CMBBEf4Xs2Zq2SFBP/ofh0JZCN0JLtkIwh H935e5t3iRvZoPsCX2Ge7EB+QUzpsigTwW4YGLvBbbMoKUuZVUqsQaHovWmHZJ7cdDGauVu0jp gx5rshSUTXWArzsPA5US+w/U4eTbMAfM70ef4XNSv/Te/KKFEVddXabuuUvrycIHSiPN4TtRDs +/7F1hojRnCAAAA To: Mathias Nyman , Greg Kroah-Hartman Cc: Mathias Nyman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Stephen Boyd , Ricardo Ribalda Delgado X-Mailer: b4 0.12.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3114; i=ribalda@chromium.org; h=from:subject:message-id; bh=kHas2cbddrKrdeEKJZphZ/TYxBnPicfD6owEY8RcqKA=; b=owEBbQKS/ZANAwAKAdE30T7POsSIAcsmYgBkeKJlheKCvOSufBlOm/CAXom89gI67JO03eo3F NAlQpmwKE6JAjMEAAEKAB0WIQREDzjr+/4oCDLSsx7RN9E+zzrEiAUCZHiiZQAKCRDRN9E+zzrE iCYbD/9jhro1RvQjcAmFYKRMdFKXxm+fRYe7j56m4xpThqniiSk6izQhIGIgjSooxtmsi11fXSI W41V4jM61+0oeTAGsKnvD5TS5dXF/71nVzv57KbngZ+HJ5w/ZKrVKQr7Yf1347QtQQJV3cOcEZy II3a02j2knLU3E6z8BwvILe2L+Ip+x31wfDEkOfvsY8B1E4TgcBSPAF3v2xnnXP7UvcO7bzYCZb riSbrXdMIpedEAXQswGdvpo/Sf+WrzmLgsY34dH54JbjD8EMhWgNdZBtRlHN1G6ICc0X8NG76gV N0qPBeDb9KKuVq5FPMj/Q6fnu6XswCvcd8otIZDkqDkkjhEGTGQ/ctBWs0u/OKlz70XeBSfuykn QHF3Yie35u9m79WT9fvhr1GVZb1tL5SYAf4nie6waRKfenGLEGY/psqlO0CYvzZpxNURPuXbinB Tlh5Et6jgeM1OCr7gBs/YQSrt+ZCVjqOqcWfLDvvOeTVIzf69PqIKjsmmJ9FSfNTYgLMRU6M7H5 kDw4Q/2L75uGxivy0z2fLKfdrZcQ+F7fp4G08gOA+pt7D6MNk24ywoYD1L9v0n+2iYGGgVPUcDL kGsoIz0lVel38YZhA+DhlavJjpdV5S+5CrUcB0i6Kr9mJfGXGH6zEA6rvpDna3fc9d+CR8YYeyz 6NcnI7SGAuSL01Q== X-Developer-Key: i=ribalda@chromium.org; a=openpgp; fpr=9EC3BB66E2FC129A6F90B39556A0D81F9F782DA9 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org xhci_debugfs_create_endpoint needs to take the mm->mmap_sem, which is not serialized with the hcd->bandwidth_mutex across the codebase. Without this patch a deadlock has been observed with the uvc driver at the functions v4l2_mmap() and usb_set_interface(). Cc: Stephen Boyd Fixes: 167657a1bb5f ("xhci: don't create endpoint debugfs entry before ring buffer is set.") Signed-off-by: Ricardo Ribalda Delgado --- Even though I do not have a proper reproducer for this, I do not see this deadlock happening after fuzzing locally my kernel. I am not used to this subsystem, so please take a careful look at this patch :). Thanks! --- Changes in v2: - Fix Stepeh email. Thanks Greg! - Update cover to note that with this patch the deadlock does not happen. - Link to v1: https://lore.kernel.org/r/20230531-xhci-deadlock-v1-1-57780bff5124@chromium.org --- drivers/usb/host/xhci-debugfs.c | 4 ++++ drivers/usb/host/xhci.c | 4 ++-- 2 files changed, 6 insertions(+), 2 deletions(-) --- base-commit: 48b1320a674e1ff5de2fad8606bee38f724594dc change-id: 20230531-xhci-deadlock-de2ab21c90bc Best regards, diff --git a/drivers/usb/host/xhci-debugfs.c b/drivers/usb/host/xhci-debugfs.c index 99baa60ef50f..2acce2af2ca9 100644 --- a/drivers/usb/host/xhci-debugfs.c +++ b/drivers/usb/host/xhci-debugfs.c @@ -238,6 +238,10 @@ static int xhci_ring_open(struct inode *inode, struct file *file) int i; struct xhci_file_map *f_map; const char *file_name = file_dentry(file)->d_iname; + struct xhci_ring *ring = *(struct xhci_ring **)inode->i_private; + + if (!ring) + return -EAGAIN; for (i = 0; i < ARRAY_SIZE(ring_files); i++) { f_map = &ring_files[i]; diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 78790dc13c5f..2715900b2540 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -1930,6 +1930,8 @@ int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev, ep_ctx = xhci_get_ep_ctx(xhci, virt_dev->in_ctx, ep_index); trace_xhci_add_endpoint(ep_ctx); + xhci_debugfs_create_endpoint(xhci, virt_dev, ep_index); + xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x\n", (unsigned int) ep->desc.bEndpointAddress, udev->slot_id, @@ -2963,7 +2965,6 @@ int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev) xhci_check_bw_drop_ep_streams(xhci, virt_dev, i); virt_dev->eps[i].ring = virt_dev->eps[i].new_ring; virt_dev->eps[i].new_ring = NULL; - xhci_debugfs_create_endpoint(xhci, virt_dev, i); } command_cleanup: kfree(command->completion); @@ -2989,7 +2990,6 @@ void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev) /* Free any rings allocated for added endpoints */ for (i = 0; i < 31; i++) { if (virt_dev->eps[i].new_ring) { - xhci_debugfs_remove_endpoint(xhci, virt_dev, i); xhci_ring_free(xhci, virt_dev->eps[i].new_ring); virt_dev->eps[i].new_ring = NULL; }