From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 2DBA03B8D7B; Thu, 14 May 2026 05:07:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778735272; cv=none; b=jqQddBb9zdwSAC6PHJLgmy/sGyqOcB0HI+WJqG4K8gMh4YJnSvBC2WwqlV/VIL/CUNHEJ49MeqGDatGA5NXJbac47O/lVdLZl0PY3reMNHRKSrK2Tfkd4V28Nr641maOtmMYxIj2l2YARtnSf2fBBQZlELrCge+K2/EDXbE2qCc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778735272; c=relaxed/simple; bh=ce3AeHJV8yA0xKyUjIxramcUgkGMSx1azmaa1bteAa0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=RHoNAShzKDHM3roKOQN3E43j76jzB4EbcdFYEfXD3ApRqS+1lehLLH7jB0/2ZLnmgZ50sqLvyV7oPBaeP42xKnWaJiBAAK9uT3atlH+sQMAyOQYezsJt0maGmiWXeJGuvME3s/dFN0oG30DqJ+jQUSVdUeWS8zBVGrf04Gy4+Ck= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=KgHc+bOn; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="KgHc+bOn" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EF4261655; Wed, 13 May 2026 22:07:44 -0700 (PDT) Received: from entos-yitian-01.Arm.com (unknown [10.168.197.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E43C13F7B4; Wed, 13 May 2026 22:07:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1778735270; bh=ce3AeHJV8yA0xKyUjIxramcUgkGMSx1azmaa1bteAa0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KgHc+bOn9lgikGgIomgvWGL7kqneuNOKKQ+fOrKWE/NieiqN2IOjN5N29xio9U/Gs tBlE8ab9OSGUZFsIgarUDezyF9gM9cPeTqnwWlC2UBGo0zeYocjDsihl89fxbt8ze6 h1nNyx74R72oscuS5m7ZFFQvmtdjAxbza+RG+LqQ= From: Jia He To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, kasan-dev@googlegroups.com, linux-mm@kvack.org Cc: Arnd Bergmann , Greg Kroah-Hartman , Alexander Viro , Christian Brauner , Jan Kara , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Brendan Higgins , David Gow , Rae Moar , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , Jia He , "Paul E. McKenney" , Petr Mladek , Kees Cook , David Disseldorp Subject: [PATCH 5/7] misc: reject duplicate names in misc_register() Date: Thu, 14 May 2026 05:04:53 +0000 Message-Id: <20260514050455.2954509-6-justin.he@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260514050455.2954509-1-justin.he@arm.com> References: <20260514050455.2954509-1-justin.he@arm.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The miscdev kunit suite registers two miscdevices with the same name and expects -EEXIST. The second call currently goes all the way to sysfs_create_dir_ns(), which prints "cannot create duplicate filename" with a backtrace on every run. Walk misc_list under misc_mtx, return -EEXIST on a name collision and free the just-allocated minor before returning. To: Arnd Bergmann To: Greg Kroah-Hartman Signed-off-by: Jia He --- drivers/char/misc.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/char/misc.c b/drivers/char/misc.c index 726516fb0a3b..d6ffa21ac495 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -248,6 +248,28 @@ int misc_register(struct miscdevice *misc) } } + /* + * Detect duplicate names up-front so the subsequent + * device_create_with_groups() does not trip + * sysfs_create_dir_ns()->sysfs_warn_dup(), which unconditionally + * dumps a stack trace. Both the existing miscdev kunit suite + * (miscdev_test_duplicate_name) and any caller racing on the same + * name would otherwise pollute dmesg on every -EEXIST. + */ + { + struct miscdevice *c; + + list_for_each_entry(c, &misc_list, list) { + if (strcmp(c->name, misc->name) == 0) { + misc_minor_free(misc->minor); + if (is_dynamic) + misc->minor = MISC_DYNAMIC_MINOR; + err = -EEXIST; + goto out; + } + } + } + dev = MKDEV(MISC_MAJOR, misc->minor); misc->this_device = -- 2.34.1