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Thu, 09 Oct 2025 03:57:30 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Randy Dunlap , Marco Elver , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. 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Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v7 06/23] mm/ksw: add singleton debugfs interface Date: Thu, 9 Oct 2025 18:55:42 +0800 Message-ID: <20251009105650.168917-7-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251009105650.168917-1-wangjinchao600@gmail.com> References: <20251009105650.168917-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 844842000D X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: q1htrpzmau18waubnimyimh8n1hd4abx X-HE-Tag: 1760007452-40324 X-HE-Meta: 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 I0yozqm9 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Provide the debugfs config file to read or update the configuration. Only a single process can open this file at a time, enforced using atomic config_file_busy, to prevent concurrent access. ksw_get_config() exposes the configuration pointer as const. Signed-off-by: Jinchao Wang --- mm/kstackwatch/kernel.c | 104 +++++++++++++++++++++++++++++++++-- mm/kstackwatch/kstackwatch.h | 3 + 2 files changed, 103 insertions(+), 4 deletions(-) diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c index 3b7009033dd4..898ebb2966fe 100644 --- a/mm/kstackwatch/kernel.c +++ b/mm/kstackwatch/kernel.c @@ -1,13 +1,18 @@ // SPDX-License-Identifier: GPL-2.0 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include #include #include #include +#include #include "kstackwatch.h" +static atomic_t dbgfs_config_busy = ATOMIC_INIT(0); static struct ksw_config *ksw_config; +static struct dentry *dbgfs_config; +static struct dentry *dbgfs_dir; struct param_map { const char *name; /* long name */ @@ -74,7 +79,7 @@ static int ksw_parse_param(struct ksw_config *config, const char *key, * - sp_offset |so (u16) : offset from stack pointer at func_offset * - watch_len |wl (u16) : watch length (1,2,4,8) */ -static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) +static int ksw_parse_config(char *buf, struct ksw_config *config) { char *part, *key, *val; int ret; @@ -109,20 +114,111 @@ static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) return 0; } +static ssize_t ksw_dbgfs_read(struct file *file, char __user *buf, size_t count, + loff_t *ppos) +{ + return simple_read_from_buffer(buf, count, ppos, ksw_config->user_input, + ksw_config->user_input ? strlen(ksw_config->user_input) : 0); +} + +static ssize_t ksw_dbgfs_write(struct file *file, const char __user *buffer, + size_t count, loff_t *ppos) +{ + char input[MAX_CONFIG_STR_LEN]; + int ret; + + if (count == 0 || count >= sizeof(input)) + return -EINVAL; + + if (copy_from_user(input, buffer, count)) + return -EFAULT; + + input[count] = '\0'; + strim(input); + + if (!strlen(input)) { + pr_info("config cleared\n"); + return count; + } + + ret = ksw_parse_config(input, ksw_config); + if (ret) { + pr_err("Failed to parse config %d\n", ret); + return ret; + } + + return count; +} + +static int ksw_dbgfs_open(struct inode *inode, struct file *file) +{ + if (atomic_cmpxchg(&dbgfs_config_busy, 0, 1)) + return -EBUSY; + return 0; +} + +static int ksw_dbgfs_release(struct inode *inode, struct file *file) +{ + atomic_set(&dbgfs_config_busy, 0); + return 0; +} + +static const struct file_operations kstackwatch_fops = { + .owner = THIS_MODULE, + .open = ksw_dbgfs_open, + .read = ksw_dbgfs_read, + .write = ksw_dbgfs_write, + .release = ksw_dbgfs_release, + .llseek = default_llseek, +}; + +const struct ksw_config *ksw_get_config(void) +{ + return ksw_config; +} + static int __init kstackwatch_init(void) { + int ret = 0; + ksw_config = kzalloc(sizeof(*ksw_config), GFP_KERNEL); - if (!ksw_config) - return -ENOMEM; + if (!ksw_config) { + ret = -ENOMEM; + goto err_alloc; + } + + dbgfs_dir = debugfs_create_dir("kstackwatch", NULL); + if (!dbgfs_dir) { + ret = -ENOMEM; + goto err_dir; + } + + dbgfs_config = debugfs_create_file("config", 0600, dbgfs_dir, NULL, + &kstackwatch_fops); + if (!dbgfs_config) { + ret = -ENOMEM; + goto err_file; + } pr_info("module loaded\n"); return 0; + +err_file: + debugfs_remove_recursive(dbgfs_dir); + dbgfs_dir = NULL; +err_dir: + kfree(ksw_config); + ksw_config = NULL; +err_alloc: + return ret; } static void __exit kstackwatch_exit(void) { + debugfs_remove_recursive(dbgfs_dir); + kfree(ksw_config->func_name); + kfree(ksw_config->user_input); kfree(ksw_config); - pr_info("module unloaded\n"); } diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h index a7bad207f863..983125d5cf18 100644 --- a/mm/kstackwatch/kstackwatch.h +++ b/mm/kstackwatch/kstackwatch.h @@ -29,4 +29,7 @@ struct ksw_config { char *user_input; }; +// singleton, only modified in kernel.c +const struct ksw_config *ksw_get_config(void); + #endif /* _KSTACKWATCH_H */ -- 2.43.0