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Fri, 12 Sep 2025 03:12:25 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Kees Cook , Alice Ryhl , Sami Tolvanen , Miguel Ojeda , Masahiro Yamada , Rong Xu , Naveen N Rao , David Kaplan , Andrii Nakryiko , Jinjie Ruan , Nam Cao , workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, Andrey Ryabinin , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com, "David S. Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v4 06/21] mm/ksw: add singleton /proc/kstackwatch interface Date: Fri, 12 Sep 2025 18:11:16 +0800 Message-ID: <20250912101145.465708-7-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250912101145.465708-1-wangjinchao600@gmail.com> References: <20250912101145.465708-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A5A8410000E X-Stat-Signature: hr51zsegas7ms3w8km61zg448fthdomp X-Rspam-User: X-HE-Tag: 1757671947-104047 X-HE-Meta: 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 DWpcH/Ax 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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 /proc/kstackwatch 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 | 75 +++++++++++++++++++++++++++++++++++- mm/kstackwatch/kstackwatch.h | 3 ++ 2 files changed, 77 insertions(+), 1 deletion(-) diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c index 1502795e02af..8e1dca45003e 100644 --- a/mm/kstackwatch/kernel.c +++ b/mm/kstackwatch/kernel.c @@ -3,7 +3,10 @@ #include #include +#include +#include #include +#include #include "kstackwatch.h" @@ -12,6 +15,7 @@ MODULE_DESCRIPTION("Kernel Stack Watch"); MODULE_LICENSE("GPL"); static struct ksw_config *ksw_config; +static atomic_t config_file_busy = ATOMIC_INIT(0); /* * Format of the configuration string: @@ -23,7 +27,7 @@ static struct ksw_config *ksw_config; * - local_var_offset : offset from the stack pointer at function+ip_offset * - local_var_len : length of the local variable(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 *func_part, *local_var_part = NULL; char *token; @@ -92,18 +96,87 @@ static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) return -EINVAL; } +static ssize_t kstackwatch_proc_write(struct file *file, + const char __user *buffer, size_t count, + loff_t *pos) +{ + 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 kstackwatch_proc_show(struct seq_file *m, void *v) +{ + seq_printf(m, "%s\n", ksw_config->config_str); + return 0; +} + +static int kstackwatch_proc_open(struct inode *inode, struct file *file) +{ + if (atomic_cmpxchg(&config_file_busy, 0, 1)) + return -EBUSY; + + return single_open(file, kstackwatch_proc_show, NULL); +} + +static int kstackwatch_proc_release(struct inode *inode, struct file *file) +{ + atomic_set(&config_file_busy, 0); + return single_release(inode, file); +} + +static const struct proc_ops kstackwatch_proc_ops = { + .proc_open = kstackwatch_proc_open, + .proc_read = seq_read, + .proc_write = kstackwatch_proc_write, + .proc_lseek = seq_lseek, + .proc_release = kstackwatch_proc_release, +}; + +const struct ksw_config *ksw_get_config(void) +{ + return ksw_config; +} static int __init kstackwatch_init(void) { ksw_config = kzalloc(sizeof(*ksw_config), GFP_KERNEL); if (!ksw_config) return -ENOMEM; + if (!proc_create("kstackwatch", 0600, NULL, &kstackwatch_proc_ops)) { + pr_err("create proc kstackwatch fail"); + kfree(ksw_config); + return -ENOMEM; + } + pr_info("module loaded\n"); return 0; } static void __exit kstackwatch_exit(void) { + remove_proc_entry("kstackwatch", NULL); kfree(ksw_config); pr_info("module unloaded\n"); diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h index 7c595c5c24d1..277b192f80fa 100644 --- a/mm/kstackwatch/kstackwatch.h +++ b/mm/kstackwatch/kstackwatch.h @@ -35,4 +35,7 @@ struct ksw_config { char config_str[MAX_CONFIG_STR_LEN]; }; +// singleton, only modified in kernel.c +const struct ksw_config *ksw_get_config(void); + #endif /* _KSTACKWATCH_H */ -- 2.43.0