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Message-ID: <20250924115124.194940-7-wangjinchao600@gmail.com>
Date: Wed, 24 Sep 2025 19:50:49 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Mike Rapoport <rppt@...nel.org>,
Alexander Potapenko <glider@...gle.com>,
Randy Dunlap <rdunlap@...radead.org>,
Jonathan Corbet <corbet@....net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>,
Mel Gorman <mgorman@...e.de>,
Valentin Schneider <vschneid@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
"Liang, Kan" <kan.liang@...ux.intel.com>,
David Hildenbrand <david@...hat.com>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Suren Baghdasaryan <surenb@...gle.com>,
Michal Hocko <mhocko@...e.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
Bill Wendling <morbo@...gle.com>,
Justin Stitt <justinstitt@...gle.com>,
Kees Cook <kees@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Sami Tolvanen <samitolvanen@...gle.com>,
Miguel Ojeda <ojeda@...nel.org>,
Masahiro Yamada <masahiroy@...nel.org>,
Rong Xu <xur@...gle.com>,
Naveen N Rao <naveen@...nel.org>,
David Kaplan <david.kaplan@....com>,
Andrii Nakryiko <andrii@...nel.org>,
Jinjie Ruan <ruanjinjie@...wei.com>,
Nam Cao <namcao@...utronix.de>,
workflows@...r.kernel.org,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org,
linux-mm@...ck.org,
llvm@...ts.linux.dev,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
kasan-dev@...glegroups.com,
"David S. Miller" <davem@...emloft.net>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
linux-trace-kernel@...r.kernel.org
Cc: Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH v5 06/23] mm/ksw: add singleton /proc/kstackwatch interface
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 <wangjinchao600@...il.com>
---
mm/kstackwatch/kernel.c | 77 +++++++++++++++++++++++++++++++++++-
mm/kstackwatch/kstackwatch.h | 3 ++
2 files changed, 79 insertions(+), 1 deletion(-)
diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c
index 3b7009033dd4..4a06ddadd9c7 100644
--- a/mm/kstackwatch/kernel.c
+++ b/mm/kstackwatch/kernel.c
@@ -3,11 +3,15 @@
#include <linux/kstrtox.h>
#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
#include <linux/string.h>
+#include <linux/uaccess.h>
#include "kstackwatch.h"
static struct ksw_config *ksw_config;
+static atomic_t config_file_busy = ATOMIC_INIT(0);
struct param_map {
const char *name; /* long name */
@@ -74,7 +78,7 @@ 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;
@@ -109,18 +113,89 @@ static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config)
return 0;
}
+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->user_input);
+ 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->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
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