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b=E+Ez+r/wxzU2Gtcf5D8LdDilirwAFUov5C06lfDFwMgTzQVfbxMtt8fKYuGRsMRh4 Ckk9DN/UFiXuxu9YL3fuJE1EWmK9hRCH3J9jOkyAoKEzOflfONYsx3P9+qRLeFxGDS /40M8mqyFHF8oYbXu1Q4J7JKbzxQEJ1GkgOZm6vz5wKg3rhpJPRpykA8y0NgnKZQ/l mpendCXxg/qj9vJFA6Ul5z1piuGWhxjd1u4ugCdjQbkV4cRv9KN+exxYsD+XXDuRdm smu4R2wbuW2Omoi0r7pRXtoIQkEdgbLO333wdPaf0nMrT2B0lmnYWO+uXkuGHKxxCT tADO5izDMPJ4Q== From: Christian Brauner Date: Mon, 02 Nov 2026 15:48:45 +0100 Subject: [PATCH RFC 05/16] proc: let procfs own the seq_file of proc_create_seq() and friends X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261102-work-procfs-core-v1-5-75df35e4f8b8@kernel.org> References: <20261102-work-procfs-core-v1-0-75df35e4f8b8@kernel.org> In-Reply-To: <20261102-work-procfs-core-v1-0-75df35e4f8b8@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever X-Mailer: b4 0.17-dev X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7242A180005 X-Stat-Signature: qaqq9me3158jkukq73qu31dyjs3zx87q X-Rspam-User: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1793631041-327038 X-HE-Meta: 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 8VRe2bIL nQWdcrf6/dc9r3uVdUM75YUUgFjuaUR2yoH9jG3KMTDXRzH1fwMOO3qpNBfGTqMQc5kwF+Ga92y/LKchTq8NvyQ8Rz+OxTxCmYPN9Xd6Vj60DZrhf3QltJ6H7LnjD9TgwB+yw/hBBV2Tmsd5YlNnS4dgQkPAGlm1/xjHpPO+oea2zayXhUqyJ+VMRTyDIP+qYkfUX0yOU1KRPLSfMfzixM8Qr428R+H/Ns2mkKFTYh20ttiHanBe4xTbyos8qRf5/uyBjGwXGWGFszk7peYqNWCIUMGE9WYK5PK1Wx0S6f4mxN33thEKsprMpVlkMKTjY0GQtGD+LDc7kDK0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 proc_create_seq_private(), proc_create_single_data() and their network namespace variants keep the seq_operations or the show function in the entry already. Let procfs own the seq_file for all of them. For the network namespace variants ->proc_open() and ->proc_release() keep taking and dropping the reference to the network namespace. That's most of /proc/net, among them the files of xt_hashlimit and /proc/net/dev_snmp6/. A reader that faults on its buffer no longer holds up their removal. Reported-by: Chris Mason Fixes: 786d7e1612f0 ("Fix rmmod/read/write races in /proc entries") Signed-off-by: Christian Brauner (Amutable) --- fs/proc/generic.c | 42 ++++-------------------------------------- fs/proc/proc_net.c | 40 +++++++++++++--------------------------- 2 files changed, 17 insertions(+), 65 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index eff5c38e2219..6ed8bc313db0 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -694,30 +694,9 @@ struct proc_dir_entry *proc_create(const char *name, umode_t mode, } EXPORT_SYMBOL(proc_create); -static int proc_seq_open(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - if (de->state_size) - return seq_open_private(file, de->seq_ops, de->state_size); - return seq_open(file, de->seq_ops); -} - -static int proc_seq_release(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - if (de->state_size) - return seq_release_private(inode, file); - return seq_release(inode, file); -} - +/* procfs owns the seq_file of these, see pde_seq_ops */ static const struct proc_ops proc_seq_ops = { /* not permanent -- can call into arbitrary seq_operations */ - .proc_open = proc_seq_open, - .proc_read_iter = seq_read_iter, - .proc_lseek = seq_lseek, - .proc_release = proc_seq_release, }; struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode, @@ -732,25 +711,11 @@ struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode, p->proc_ops = &proc_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_seq_private); -static int proc_single_open(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - return single_open(file, de->single_show, de->data); -} - -static const struct proc_ops proc_single_ops = { - /* not permanent -- can call into arbitrary ->single_show */ - .proc_open = proc_single_open, - .proc_read_iter = seq_read_iter, - .proc_lseek = seq_lseek, - .proc_release = single_release, -}; - struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode, struct proc_dir_entry *parent, int (*show)(struct seq_file *, void *), void *data) @@ -760,8 +725,9 @@ struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode, p = proc_create_reg(name, mode, &parent, data); if (!p) return NULL; - p->proc_ops = &proc_single_ops; + p->proc_ops = &proc_seq_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_single_data); diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index df5484813d5d..fa485581d05e 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -37,13 +37,13 @@ static struct net *get_proc_net(const struct inode *inode) return maybe_get_net(PDE_NET(PDE(inode))); } +/* procfs opened the seq_file and allocated its state, see pde_seq_ops */ static int seq_open_net(struct inode *inode, struct file *file) { - unsigned int state_size = PDE(inode)->state_size; - struct seq_net_private *p; + struct seq_net_private *p = ((struct seq_file *)file->private_data)->private; struct net *net; - WARN_ON_ONCE(state_size < sizeof(*p)); + WARN_ON_ONCE(PDE(inode)->state_size < sizeof(*p)); if (file->f_mode & FMODE_WRITE && !PDE(inode)->write) return -EACCES; @@ -51,12 +51,6 @@ static int seq_open_net(struct inode *inode, struct file *file) net = get_proc_net(inode); if (!net) return -ENXIO; - - p = __seq_open_private(file, PDE(inode)->seq_ops, state_size); - if (!p) { - put_net(net); - return -ENOMEM; - } #ifdef CONFIG_NET_NS p->net = net; netns_tracker_alloc(net, &p->ns_tracker, GFP_KERNEL); @@ -77,18 +71,13 @@ static void seq_file_net_put_net(struct seq_file *seq) static int seq_release_net(struct inode *ino, struct file *f) { - struct seq_file *seq = f->private_data; - - seq_file_net_put_net(seq); - seq_release_private(ino, f); + seq_file_net_put_net(f->private_data); return 0; } static const struct proc_ops proc_net_seq_ops = { .proc_open = seq_open_net, - .proc_read = seq_read, .proc_write = proc_simple_write, - .proc_lseek = seq_lseek, .proc_release = seq_release_net, }; @@ -125,6 +114,7 @@ struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode, p->proc_ops = &proc_net_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; return proc_register(parent, p); } EXPORT_SYMBOL_GPL(proc_create_net_data); @@ -170,6 +160,7 @@ struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode p->proc_ops = &proc_net_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; p->write = write; return proc_register(parent, p); } @@ -177,32 +168,25 @@ EXPORT_SYMBOL_GPL(proc_create_net_data_write); static int single_open_net(struct inode *inode, struct file *file) { - struct proc_dir_entry *de = PDE(inode); - struct net *net; - int err; + struct net *net = get_proc_net(inode); - net = get_proc_net(inode); if (!net) return -ENXIO; - - err = single_open(file, de->single_show, net); - if (err) - put_net(net); - return err; + ((struct seq_file *)file->private_data)->private = net; + return 0; } static int single_release_net(struct inode *ino, struct file *f) { struct seq_file *seq = f->private_data; + put_net(seq->private); - return single_release(ino, f); + return 0; } static const struct proc_ops proc_net_single_ops = { .proc_open = single_open_net, - .proc_read = seq_read, .proc_write = proc_simple_write, - .proc_lseek = seq_lseek, .proc_release = single_release_net, }; @@ -218,6 +202,7 @@ struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode, pde_force_lookup(p); p->proc_ops = &proc_net_single_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; return proc_register(parent, p); } EXPORT_SYMBOL_GPL(proc_create_net_single); @@ -261,6 +246,7 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo pde_force_lookup(p); p->proc_ops = &proc_net_single_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; p->write = write; return proc_register(parent, p); } -- 2.53.0