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 A01592F362B; Wed, 14 Jan 2026 04:31:53 +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=1768365122; cv=none; b=d4pQV0LL72wPcox4tOow8LBYUQByY/DEdQkJ6Ot4qxnoHlMvZ/wollcmo6oEkDRiJ1b8MeTS4ExKDRsnMbsQWNegDWDOekdV0mBXlaKUoOQxf5UaerrgOP9XU3soEUlKYX4ko052RZXuZ/qcWSoO+pTTT97upYEniSp9oK1kQ+4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768365122; c=relaxed/simple; bh=DRDmIOvg1abJl+/JeOeB7ulbY6rmfIdfsjab/8Rf3SE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mJ0gp/UFXOmixC2yyJrJP0yU8r/jMWgHTVCqIJCBf5TTosm2DRL0wmtS/2LyHxdzewkxqL81CL03ix6WoLw0m7KVXpnrYkDPBfb6sJMG5K3+ALD762xCmzJysCVeSCmHhn6g9NcY13hSb3HrndXh7ZiRLMY9SqqtuaoxnxwS9KI= 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=qP/LMEqQ; 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="qP/LMEqQ" 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=5yAr+d87WTeC2PgxeAVXbzQHbhxJXXfFmShFH8sOGxA=; b=qP/LMEqQn/eejt+MO24g8FWM88 7F8UtvM/lckMH5gaT154etzpDmO6cgFX5OTi/Qrsxfm2icW83e0ygEK8o+By4OcgdgovO7WiNMCrL 6PuC1Wq6qnbKzCxeG2saWHdisI677t75amgt87uB4fvhrXCZCwCbM8OUguwNJh/m1BOxgJIKe1clZ jJgKsjA64BHapqtZ0JIv8bXzDD9/ruvnKgrD4E0N+OpIfik96UNnVyqpidf0ho50GyDRgLKyXxTkg +hDZ+YB0PW++51x5s6n+MEYJV3ABYC2Vu4cOHqHllqjXIOkLHdPGu9StlYgJHB9O0bzne9I2fiMvb 0baYcFOQ==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.99 #2 (Red Hat Linux)) id 1vfsZF-0000000GInv-2OJH; Wed, 14 Jan 2026 04:33:13 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Christian Brauner , Jan Kara , Mateusz Guzik , Paul Moore , Jens Axboe , audit@vger.kernel.org, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 24/68] struct filename ->refcnt doesn't need to be atomic Date: Wed, 14 Jan 2026 04:32:26 +0000 Message-ID: <20260114043310.3885463-25-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260114043310.3885463-1-viro@zeniv.linux.org.uk> References: <20260114043310.3885463-1-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. Acked-by: Paul Moore Signed-off-by: Al Viro --- fs/namei.c | 12 ++++++------ include/linux/fs.h | 8 +------- kernel/auditsc.c | 6 +++--- 3 files changed, 10 insertions(+), 16 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index b76cc43fe89d..f4359825ba48 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -150,7 +150,7 @@ 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) @@ -292,13 +292,13 @@ 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)) @@ -328,12 +328,12 @@ int delayed_getname_uflags(struct delayed_filename *v, const char __user *string int putname_to_delayed(struct delayed_filename *v, struct filename *name) { - if (likely(atomic_read(&name->refcnt) == 1)) { + if (likely(name->refcnt == 1)) { v->__incomplete_filename = name; return 0; } + name->refcnt--; v->__incomplete_filename = do_getname_kernel(name->name, true); - putname(name); return PTR_ERR_OR_ZERO(v->__incomplete_filename); } diff --git a/include/linux/fs.h b/include/linux/fs.h index f1612a7dffd0..6a26ee347517 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2412,7 +2412,7 @@ struct audit_names; struct __filename_head { const char *name; /* pointer to actual string */ - atomic_t refcnt; + int refcnt; struct audit_names *aname; }; #define EMBEDDED_NAME_MAX (192 - sizeof(struct __filename_head)) @@ -2527,12 +2527,6 @@ 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; -} - DEFINE_CLASS(filename, struct filename *, putname(_T), getname(p), const char __user *p) EXTEND_CLASS(filename, _kernel, getname_kernel(p), const char *p) EXTEND_CLASS(filename, _flags, getname_flags(p, f), const char __user *p, unsigned int f) diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 67d8da927381..86a44b162a87 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2191,7 +2191,7 @@ void __audit_getname(struct filename *name) n->name = name; n->name_len = AUDIT_NAME_FULL; name->aname = n; - refname(name); + name->refcnt++; } static inline int audit_copy_fcaps(struct audit_names *name, @@ -2323,7 +2323,7 @@ void __audit_inode(struct filename *name, const struct dentry *dentry, return; if (name) { n->name = name; - refname(name); + name->refcnt++; } out: @@ -2445,7 +2445,7 @@ void __audit_inode_child(struct inode *parent, if (found_parent) { found_child->name = found_parent->name; found_child->name_len = AUDIT_NAME_FULL; - refname(found_child->name); + found_child->name->refcnt++; } } -- 2.47.3