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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WxVxzqco; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C29B2607816B; Wed, 4 Nov 2026 19:55:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WxVxzqco Received: by smtp.kernel.org (Postfix) with ESMTPSA id 721521F000C1; Wed, 4 Nov 2026 19:55:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793822133; bh=C2fJYdTojRFSaODFdjPHql9M0bzE3FJwr1E018LBBO4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=WxVxzqcomPDLAWsqX85EWcLe7WZlzoKJpHDpOQhf+KZ1aYuixFo4RGC5WENxIeYDR pLwBWxDYw0foUZ3wHytSbwfCa7iq8dLIZnc5m2y8FT0LfPDL7Q2pae5sK1fKW87eH/ TLoxZJitlHu5XhrmddtW5nHOKeuonavA/4uOaPJGmBoWC6YghAhb5YkhkwxhSp7tHZ SnDT1yEyHPjdo3S7ahmm98p5SQhtKbsglzOsqjH27sqF26J+nVkJrN5qpLWC+cZqHa 3bxRMiT/Z2318AVzkaEXIjv3kDFVAW7sr0AInZ9NSC6cPhwH5gTxJMnKg8DEI8HGOJ jel/AuRNeS6+A== From: Christian Brauner 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 Subject: [PATCH RESEND v2 23/30] dyndbg: let procfs copy in writes to /proc/dynamic_debug/control Date: Wed, 4 Nov 2026 20:55:19 +0100 Message-ID: <20261104-work-procfs-fs-v2-23-319e0f9a8aae@kernel.org> In-Reply-To: <20261104-work-procfs-fs-v2-0-319e0f9a8aae@kernel.org> References: <20261104-work-procfs-fs-v2-0-319e0f9a8aae@kernel.org> X-Mailing-List: linux-debuggers@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2288; i=brauner@kernel.org; h=from:subject:message-id; bh=Awi3L5zR/nArf9JZW1OMhl80jxJR2cXziAHCcuF5CR4=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS97nHPjBBTr3NykX/wLUHBgNnn4SS7+fVKVwr6yxuXL 0uRqJrSUcrCIMbFICumyOLQbhIut5ynYrNRpgbMHFYmkCEMXJwCMJEb0xn+Fy+YXCV0Oe/Eaz8H 4b8ha/yUgz2teDZt31XB+vfCvnbjCEaGI7bdptPVH0oejHTQsv2wPFNAJufAZvvExUsuC73W+Mv LCwA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit Move the parsing into ddebug_proc_write_buf() and implement ->proc_write_buf() with it so procfs copies in what is written before it pins the entry. The debugfs file keeps copying in itself. Writes larger than USER_BUF_PAGE - 1 bytes to the procfs file now fail with -EINVAL from procfs instead of -E2BIG, and without the "expected <4096 bytes into control" warning. Signed-off-by: Christian Brauner (Amutable) --- lib/dynamic_debug.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 64a211290872..1d6012c9eb41 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -1002,11 +1002,28 @@ __setup("dyndbg=", dyndbg_setup); * command text from userspace, parses and executes it. */ #define USER_BUF_PAGE 4096 + +static ssize_t ddebug_proc_write_buf(struct file *file, char *buf, size_t len, + loff_t *offp) +{ + int ret; + + if (len == 0) + return 0; + v2pr_info("read %zu bytes from userspace\n", len); + + ret = ddebug_exec_queries(buf, NULL); + if (ret < 0) + return ret; + + *offp += len; + return len; +} + static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf, size_t len, loff_t *offp) { - char *tmpbuf; - int ret; + char *tmpbuf __free(kfree) = NULL; if (len == 0) return 0; @@ -1017,15 +1034,7 @@ static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf, tmpbuf = memdup_user_nul(ubuf, len); if (IS_ERR(tmpbuf)) return PTR_ERR(tmpbuf); - v2pr_info("read %zu bytes from userspace\n", len); - - ret = ddebug_exec_queries(tmpbuf, NULL); - kfree(tmpbuf); - if (ret < 0) - return ret; - - *offp += len; - return len; + return ddebug_proc_write_buf(file, tmpbuf, len, offp); } /* @@ -1196,7 +1205,8 @@ static const struct file_operations ddebug_proc_fops = { static const struct proc_ops proc_fops = { .proc_seq_ops = &ddebug_proc_seqops, .proc_state_size = sizeof(struct ddebug_iter), - .proc_write = ddebug_proc_write + .proc_write_buf = ddebug_proc_write_buf, + .proc_write_size = USER_BUF_PAGE - 1, }; static void ddebug_attach_module_classes(struct ddebug_table *dt, -- 2.53.0