From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AB46323373D; Sat, 29 Nov 2025 17:01:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764435702; cv=none; b=OV7/0MPD8v4Fmk0RNZs+NiBUnncZnh/ZC5rlLQNsE4KHypYit7Zf6xriOf2qwdOJFeY7LCp2YoomG4U4pD+QEGth7pA0xc2Jzko2hGycIj1p4dXEjcYWpDDxEwEavtq/sK0udkTNLFk1IUwaUgA/G0T0k0fFJw43AIgsMa7HH+8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764435702; c=relaxed/simple; bh=QPsA95FqkoqhZwspP+I0M8hqJMt14cqnl0F7hFCckZc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GSs8k2PQdSru90BeFpL1Tts0L7L42Nia4BgTbpzNZJT01eJQTUutojRG6e21szmb7YYNIfOyQL5QtIhOTQXyQsZWcNpcZr+jkgV+JBPIrwwdv3HJqd7IkwFjFD5+Eiw3phHcteoztTpT1hip1WFnR6a8idQsiOc1UpSQl3wajDw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=nORElcFX; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="nORElcFX" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=dnuK+nfSVSM8EnnK0uwzWnmtu2jEW/yLVrHY/kiG4UY=; b=nORElcFXZIM+PZtx1nWH5bOkZt VHIGK5a3y6Tv0bG/Ku5dhUwLqANlxxAZZcKTIzuFkS34gcK3Vd6WJjZ92s3w+qdFMwdc73XC75XG3 tOKIj+Q88sM8iZL6P6Rj3pW0dAjP0AgM1dKiG1++gCVcyVcfwHtdopNDq783wH+pNoUGwL/gSk94k EnVm4EqVjhKoHQ5INCAgU/Lm9vg+/y9cer5BpYLhzwrt1I+0hRf50/lHKPAiU1M0kzCrNkUf1t66N kZDj5Qn/CuYo67DxoZumbabb07B+OqvbbmdCEgScUoRUsZ2aiKi9LsBC7qQfxhR/wvO0d2PPc2US3 HkgHuUyA==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.99 #2 (Red Hat Linux)) id 1vPOKO-00000000dET-1ZhJ; Sat, 29 Nov 2025 17:01:44 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: torvalds@linux-foundation.org, brauner@kernel.org, jack@suse.cz, mjguzik@gmail.com, paul@paul-moore.com, axboe@kernel.dk, audit@vger.kernel.org, io-uring@vger.kernel.org Subject: [RFC PATCH v2 18/18] struct filename ->refcnt doesn't need to be atomic Date: Sat, 29 Nov 2025 17:01:42 +0000 Message-ID: <20251129170142.150639-19-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251129170142.150639-1-viro@zeniv.linux.org.uk> References: <20251129170142.150639-1-viro@zeniv.linux.org.uk> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: Al Viro ... or visible outside of audit, really. Note that references held in delayed_filename always have refcount 1, and from the moment of complete_getname() or equivalent point in getname...() there won't be any references to struct filename instance left in places visible to other threads. Signed-off-by: Al Viro --- fs/namei.c | 10 +++++----- include/linux/fs.h | 8 +------- kernel/auditsc.c | 6 ++++++ 3 files changed, 12 insertions(+), 12 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 8530d75fb270..d6eac90084e1 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -146,7 +146,7 @@ static inline void free_filename(struct filename *p) static inline void initname(struct filename *name) { name->aname = NULL; - atomic_set(&name->refcnt, 1); + name->refcnt = 1; } static int getname_long(struct filename *name, const char __user *filename) @@ -284,13 +284,13 @@ void putname(struct filename *name) if (IS_ERR_OR_NULL(name)) return; - refcnt = atomic_read(&name->refcnt); + refcnt = name->refcnt; if (unlikely(refcnt != 1)) { if (WARN_ON_ONCE(!refcnt)) return; - if (!atomic_dec_and_test(&name->refcnt)) - return; + name->refcnt--; + return; } if (unlikely(name->name != name->iname)) @@ -323,7 +323,7 @@ int putname_to_delayed(struct delayed_filename *v, struct filename *__name) struct filename *name __free(putname) = no_free_ptr(__name); struct filename *copy; - if (likely(atomic_read(&name->refcnt) == 1)) { + if (likely(name->refcnt == 1)) { v->__incomplete_filename = no_free_ptr(name); return 0; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 52ee3bc1baa9..b21814b93dcd 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2837,7 +2837,7 @@ struct audit_names; #define EMBEDDED_NAME_MAX 128 struct filename { const char *name; /* pointer to actual string */ - atomic_t refcnt; + int refcnt; struct audit_names *aname; const char iname[EMBEDDED_NAME_MAX]; }; @@ -2947,12 +2947,6 @@ void dismiss_delayed_filename(struct delayed_filename *); int putname_to_delayed(struct delayed_filename *, struct filename *); struct filename *complete_getname(struct delayed_filename *); -static inline struct filename *refname(struct filename *name) -{ - atomic_inc(&name->refcnt); - return name; -} - extern int finish_open(struct file *file, struct dentry *dentry, int (*open)(struct inode *, struct file *)); extern int finish_no_open(struct file *file, struct dentry *dentry); diff --git a/kernel/auditsc.c b/kernel/auditsc.c index e59a094bb9f7..d71fc73455b2 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2169,6 +2169,12 @@ static struct audit_names *audit_alloc_name(struct audit_context *context, return aname; } +static inline struct filename *refname(struct filename *name) +{ + name->refcnt++; + return name; +} + /** * __audit_getname - add a name to the list * @name: name to add -- 2.47.3