From patchwork Tue Nov 5 04:29:16 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hardik Gohil X-Patchwork-Id: 13862337 Received: from mail-pl1-f177.google.com (mail-pl1-f177.google.com [209.85.214.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9FB2618FDAC for ; Tue, 5 Nov 2024 04:29:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.177 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730780972; cv=none; b=EGY0YKPlU4yOYaymOp+aBmzbJbYRN7A0tcD/sMoEDREI0b6prH+eJNMN5reycpF/pVqVNhMIZnTe+/h85tdHRXcIMYtckUCTKKmZbNLiE53lhNYNq3WjhFfYGOO9cJyc07BGwpdvLC7zk9LY4Kw4Kh7NiDGozga4jKjSr2ZGuvM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730780972; c=relaxed/simple; bh=8SLmDpTRCFDajZT38/rFEX+2ka0yX2igg96h70rcUao=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=Gca4iPxw60M3gPDSaiPsDvfRApy8Om1EEpvOiCpYYtjOAsHCnjS17Crosex3iOUO21hUZ4eQJmB9w9XsG06os5VNV9Ikn0lp9ML5U4v8bx3VIa3IvOBt8AyTmx7CmES7Hd4uzsLBGobldG0unrPp6beAawG6xsCrj71X5c9LYgs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mvista.com; spf=pass smtp.mailfrom=mvista.com; dkim=pass (1024-bit key) header.d=mvista.com header.i=@mvista.com header.b=ACni7COb; arc=none smtp.client-ip=209.85.214.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mvista.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mvista.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=mvista.com header.i=@mvista.com header.b="ACni7COb" Received: by mail-pl1-f177.google.com with SMTP id d9443c01a7336-2110a622d76so38013415ad.3 for ; Mon, 04 Nov 2024 20:29:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mvista.com; s=google; t=1730780970; x=1731385770; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=XPgJOaKUw2i2yhBq0UrCbUBNmKfQYHEenFvmnag+ukI=; b=ACni7CObMJc6Wy8I7q730yoCc9fiiDWImF4ZPtGKV3gLxvYxLPiMRhkjDLgJi+V7ba eHakZFl4ZSfSfQmoAE7RJgtHVFFjnCRqa1eP/mhz0yFzaqY5SMVkthl/F7CBW0X68n4Q o6RdbgdP0j3wa0JQoNL7fMSe4ad/9JWvVlyXc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730780970; x=1731385770; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=XPgJOaKUw2i2yhBq0UrCbUBNmKfQYHEenFvmnag+ukI=; b=pLxrYyB3lc+lMFAZJkdG/L8hio0yJBMrI/0e6rD7pbwqkmsxK8zDzBBjMc4bkqNgww AbHABALRvnyeeJupGHVmeFQ7o8uZREZfnKmUferxlU4r/hzHL4J6Isgk+Blhg1ZMBJKk RQbQObdekozF/yErNxgYVS+j3pjklmR5VjUSR3KQ5lMXstlBk0sM4x7quHJP4G1Sxyhn GyoWUL1rYbubv+7hq1M8DFLYjv93z4LBYQf+uyU1POWllwEIMbaswCqip2NiYeZ3EYRm S9+n74xUM5PoMFNtHoyseeJKi9EJzdtsXHv+e/0shuDD2mwQFrI40PrdTILV73cdCpYp jReg== X-Gm-Message-State: AOJu0Yy6yhtl7//Bp+FLqyPDMPh+v2ijJd7BlwlGyu0oLKsukqAIXnKH 1DbQDqkpC7hL/oyZjX83J+ApDx1aUQ7BFPWEWRlfiukCuHaHzohjxMvcPercBQc= X-Google-Smtp-Source: AGHT+IFY9OIl5skQBRIO2pCUZzVxAmt0oAL+rH5hjwiRx9eykhnbWVyX5fzKpskOf4a4N7E57JH8CQ== X-Received: by 2002:a17:903:124d:b0:20c:5cb1:ddf0 with SMTP id d9443c01a7336-210c68a9c2bmr489805165ad.10.1730780969827; Mon, 04 Nov 2024 20:29:29 -0800 (PST) Received: from jupiter.mvista.com ([182.74.28.237]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-211056edc65sm69234575ad.10.2024.11.04.20.29.27 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Nov 2024 20:29:29 -0800 (PST) From: Hardik Gohil To: stable@vger.kernel.org Cc: linux-spi@vger.kernel.org, Mark Brown , Hardik Gohil Subject: [PATCH v5.4.y v5.10.y] spi: Fix deadlock when adding SPI controllers on SPI buses Date: Tue, 5 Nov 2024 09:59:16 +0530 Message-Id: <1730780956-13313-1-git-send-email-hgohil@mvista.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk X-Mailing-List: linux-spi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Mark Brown [ Upstream commit 6098475d4cb48d821bdf453c61118c56e26294f0 ] Currently we have a global spi_add_lock which we take when adding new devices so that we can check that we're not trying to reuse a chip select that's already controlled. This means that if the SPI device is itself a SPI controller and triggers the instantiation of further SPI devices we trigger a deadlock as we try to register and instantiate those devices while in the process of doing so for the parent controller and hence already holding the global spi_add_lock. Since we only care about concurrency within a single SPI bus move the lock to be per controller, avoiding the deadlock. This can be easily triggered in the case of spi-mux. Reported-by: Uwe Kleine-König Signed-off-by: Mark Brown Signed-off-by: Hardik Gohil --- This fix was not backported to v5.4 and v5.10 please also apply following fix on top of this spi: fix use-after-free of the add_lock mutex commit 6c53b45c71b4920b5e62f0ea8079a1da382b9434 upstream. Commit 6098475d4cb4 ("spi: Fix deadlock when adding SPI controllers on SPI buses") introduced a per-controller mutex. But mutex_unlock() of said lock is called after the controller is already freed: drivers/spi/spi.c | 15 +++++---------- include/linux/spi/spi.h | 3 +++ 2 files changed, 8 insertions(+), 10 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 0f9410e..58f1947 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -472,12 +472,6 @@ static LIST_HEAD(spi_controller_list); */ static DEFINE_MUTEX(board_lock); -/* - * Prevents addition of devices with same chip select and - * addition of devices below an unregistering controller. - */ -static DEFINE_MUTEX(spi_add_lock); - /** * spi_alloc_device - Allocate a new SPI device * @ctlr: Controller to which device is connected @@ -580,7 +574,7 @@ int spi_add_device(struct spi_device *spi) * chipselect **BEFORE** we call setup(), else we'll trash * its configuration. Lock against concurrent add() calls. */ - mutex_lock(&spi_add_lock); + mutex_lock(&ctlr->add_lock); status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check); if (status) { @@ -624,7 +618,7 @@ int spi_add_device(struct spi_device *spi) } done: - mutex_unlock(&spi_add_lock); + mutex_unlock(&ctlr->add_lock); return status; } EXPORT_SYMBOL_GPL(spi_add_device); @@ -2512,6 +2506,7 @@ int spi_register_controller(struct spi_controller *ctlr) spin_lock_init(&ctlr->bus_lock_spinlock); mutex_init(&ctlr->bus_lock_mutex); mutex_init(&ctlr->io_mutex); + mutex_init(&ctlr->add_lock); ctlr->bus_lock_flag = 0; init_completion(&ctlr->xfer_completion); if (!ctlr->max_dma_len) @@ -2657,7 +2652,7 @@ void spi_unregister_controller(struct spi_controller *ctlr) /* Prevent addition of new devices, unregister existing ones */ if (IS_ENABLED(CONFIG_SPI_DYNAMIC)) - mutex_lock(&spi_add_lock); + mutex_lock(&ctlr->add_lock); device_for_each_child(&ctlr->dev, NULL, __unregister); @@ -2688,7 +2683,7 @@ void spi_unregister_controller(struct spi_controller *ctlr) mutex_unlock(&board_lock); if (IS_ENABLED(CONFIG_SPI_DYNAMIC)) - mutex_unlock(&spi_add_lock); + mutex_unlock(&ctlr->add_lock); } EXPORT_SYMBOL_GPL(spi_unregister_controller); diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index ca39b33..1b9cb90 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -483,6 +483,9 @@ struct spi_controller { /* I/O mutex */ struct mutex io_mutex; + /* Used to avoid adding the same CS twice */ + struct mutex add_lock; + /* lock and mutex for SPI bus locking */ spinlock_t bus_lock_spinlock; struct mutex bus_lock_mutex;